Scintillation substance (options)

 

The invention relates to scintillation materials and can be used in nuclear physics, medicine and oil industry for recording and measuring x-ray, gamma and alpha radiation; non-destructive testing of the structure of solids; three-dimensional positron-electron and x-ray computed tomography and x-ray. Scintillation substance based on a silicate containing lutetium Lu and cerium CE, have a composition expressed by a chemical formula

CexLi2+2y-xSi1-yAbout5+y,

CexLiq+pLu2-p+2y-x-zAzSi1-yO5+y-R,

CexLiq+pLuwas 9.33-x-p-z0,67AzSi6O26-p,

where a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb; x 1×10-4F. ed. to 0.02 F. u, y from 0,024 F. ed. up to 0,09 F. ed, z is not more than 0.05 F. ed; q is not more than 0.2 F. u R not more than 0,05 F. ed.

CexLi1+q+pLu9-x-p-zAzSi6O26-p,

z is not more than 8,9 F. ed.

The resulting scintillation substances have a high density, high light output, short afterglow and a small percentage of losses ://img.russianpatents.com/img_data/86/869056.gif" border="0">

The invention relates to scintillation materials and can be used in nuclear physics, medicine and oil industry for recording and measuring x-ray, gamma and alpha radiation; non-destructive testing of the structure of solids; three-dimensional positron-electron computer tomography and x-ray computed fluoro. The urgency of the invention due to the fact that in fluoroscopy, x-ray and positron emission tomography application of new/improved scintillators will lead to a significant improvement of image quality and/or reduce the exposure time of the object ("Inorganic scintillators in medical imaging detectors". Carel W. E. van Eijk, Nuclear Instruments and Methods in Physics Research A 509 (2003) 17-25).

Known fluorescent substance powder oxyorthosilicate lutetium with cerium Lu1.98Ce0.02SiO5(A. G. Gomes, A. Bril "Preparation and Cathodolummescence of Ce3+activated yttrium silicates and some isostrural compaunds". Mat. Res. Bull. Vol.4, 1969, pp.643-650). This phosphor was investigated for use in cathodo-luminescent devices. However, it can be used for registration of x-ray, alpha - and gamma-radiation.

Known scintillation substance - crystal oxyorthosilicate lutetium with cerium 18.09.90). Crystals of this composition is grown from a melt having the composition Ce2xLu2(1-x)SiO5. In the scientific literature to refer to this crystal is widely used abbreviation LSO:Ce. Scintillation crystals Ce2-xLu2(1-x)SiO5have a number of advantages compared with other crystals: high density, high atomic number, a relatively low refractive index, high light output, short decay time of the scintillation. A disadvantage of the known scintillation material is strong variation scintillation important settings: value of the light output and energy resolution. This clearly demonstrates the experimental results of systematic measurements (U.S. patent 6413311 from 2.07.2002) commercial crystals of LSO:Ce, manufactured by CTI Inc (Knoxville, USA). Another disadvantage is the strong decrease of the light output if the device uses a crystal of LSO:Ce, must be operated at temperatures above room temperature, for example in the oil industry for the analysis of the composition of rocks in the borehole when searching for new deposits. Another disadvantage of crystals of LSO:Ce is the effect of thermoluminescence, manifested in the long loom what's in U.S. patent 4958080, the decrease in light intensity is two times describes the dependence with a time constant of about 10 minutes.

Known scintillation substance oxyorthosilicate lutetium containing cerium, Ce:Lu2SiO5existing in the form of transparent ceramics. The proposed method of producing scintillation ceramics is that in the process of synthesis of ceramics removed the pores between the powder particles Ce:Lu2SiO5in the translucent ceramics Ce:Lu2SiO5having a monoclinic structure, becomes transparent, suitable for use in medical imaging (U.S. patent 6498828 from 24.12.2002). The disadvantage of the proposed patent is that scintillation ceramics, made from a mixture of the so-called stoichiometric composition ocoordinate lutetium, which is characterized by the ratio formula units (Lu+Ce)/Si, is exactly equal to 2/1. Because congruent composition oxyorthosilicate lutetium does not coincide with the stoichiometric, stoichiometric ceramics composition necessarily contains unreacted components of the oxides, which leads to the formation of scattering centers. The presence of scattering centers significantly reduces their light yield is the most important item is prepared from oxyorthosilicate gadolinium with cerium (W. Rossner, R. Breu. "Luminescence properties cerium-doped gadolinium oxyorthosilicate ceramic scintillators". Proc. Int. Conf. on Inorganic Scintillators and Their Application STINT'95, Netherlands, Delft University, 1996, p.376-379). Scintillation elements made of transparent ceramics have 60% of their light yield less than items made of crystal Ce:Gd2SiO5.

For some applications it is highly undesirable effect of afterglow, for example, the image acquisition. When moving from an area with gamma radiation, to the plot, not emits gamma radiation, the electronic part of the device will be registryrecovery significant flux of photons emerging from the scintillation crystal due to the effect of the afterglow, and consequently, this will reduce the contrast of the border, the sensitivity and accuracy of the instrument. The afterglow affects the parameters of health systems based on the use of positron-emitting isotopes, such as 3-dimensional medical imaging (Fully-3D PET camera) for the diagnosis of cancer, and especially for MicroPET systems, designed to test new medicines. The principle of operation of 3-dimensional medical imaging based on the fact that the microscopic concentration of a substance containing a radioactive isotope, radiation is donkey radiation it instantly positron annihilates with an electron, resulting radiate two gamma ray with an energy of 511 keV, flying strictly in opposite directions. The scanner is registered both gamma-quanta with several ring of detectors, each of which contains hundreds of individual scintillation crystal elements. High density Ce:LSO provides effective absorption of all gamma-rays coming from the body of the patient under examination. Time-based registration of both quanta and numbers scintillation elements that have registered these quanta, the computation of the area in the patient's body, where he was given atom of a radioactive isotope. In the body of the patient is the scattering part of the gamma rays by the Compton effect, as a result of their registration is crystal elements, which are on a straight line. Therefore, if an item has strong persistence, it can be perceived by the registration system as a result of annihilatio at the moment, but in reality it is the effects of gamma-quanta in the previous measuring period. In the 3-dimensional medical scanners ordinary resolution use several thousands of scintillation elements rosmarie cancer and the use of thick elements section 6× 6 mm even strong afterglow crystal Ce:LSO does not lead to dramatic consequences, as by injecting large doses of radioactive substances or by reducing the rate of advance of the patient inside the ring tomograph can be achieved the required accuracy of gamma quanta.

However, the situation changes dramatically for MicroPET, which are used for studying life processes in living organisms, in particular in the brain, or to measure the distribution of new medicines throughout the body of animals (mice, rats), which test new drugs. In this case, you must use devices with the maximum spatial resolution. Currently, these are the elements with a cross section of 1× 1 mm and even with a cross section of 0.8× 0.8 mm This allows a spatial accuracy of 1 mm3. Such a small thickness of the elements leads to the fact that many gamma-rays can from different angles to cross several items in the result to calculate what portion of the scintillation radiation caused or other gamma-quantum, is a technical challenge. In this case, the afterglow becomes highly undesirable effect as it is in the Ce:LSO studied in detail (P. Dorenbost, C. van Eijekt, A. Bost, Melcher. Afterglow and thermoluminescence properties of Lu2SiO5:Ce scintilation crystals", J. Phys.Condens.Matter 6 (1994), pp.4167-4180). According to this publication, the afterglow is observed in crystals with high light output and low, and concluded that the phenomenon of persistence is a property inherent in the Ce:LSO.

Known substance oxyorthosilicate with gadolinium cerium Ce2yGd2(1-x-y)A2xSiO5where a is at least one element from the group of La (lanthanum), and Y (yttrium), the variables are changed in the range of 0<x<0.5 and 1× 10-3<y<0.1 (U.S. patent 4647781, 03.03.1987). The main drawback of this group of scintillation crystals is low light output compared to oxyorthosilicate lutetium with cerium Ce2xLu2(1-x)SiO5above.

A known method of obtaining large crystals of orthosilicate lutetium (Ce:LSO), described in U.S. patent 6413311 in which Czochralski-grown boules Ce:LSO diameter up to 60 mm and length 20 cm, a Significant drawback of these Ce:LSO Boule is that the light output varies greatly even in the same bule and decreases by 30-40% from the top bulls to the bottom. In addition, the time constant of decay of scintillations (time luminescence) may vary in a wide range of C is the variation of the critical parameters causes when commercial production must be grown by the Czochralski method a large number of Boule, cut them to pieces, to test each piece, to make a selection on the basis of test results, and then decide what parts can be used for the manufacture of scintillation elements that are necessary for medical scanners.

The known scintillation crystals Lu2(1-x)Me2xSi2O7where Me=CE, Sc, Y, In, La, Gd (US Patent 6437336) with a structured type pyrosilicate lutetium. For the cultivation of this material were used congruent compositions that are allowed to use 80% of the original melt, and the spread of the light output does not exceed 20% by volume of the bulls, and this commercial was much better than the crystal Ce:LSO. However, the crystals Lu2(1-x)Me2xSi2O7significantly lose the crystal orthosilicate lutetium Lu2SiO5on the most important scintillation parameters: density and light output. Therefore, for three-dimensional positron-electron tomography of crystal orthosilicate lutetium Ce:LSO are much more preferable, as it allows you to create a more sensitive imaging and sledovatel the early stage.

Known litiisoderzhashchego scintillation substance crystal of yttrium silicate with cerium, having the formula LiYSiO4(M. E. Globus, B. C. Greene. "Inorganic scintillators", ed. "ACT", Kharkov, (2000), page 51). Crystal, doped with 5% CE3+has a maximum peak luminescence at 410 nm, time constant luminescence equal to 38 nanoseconds, and the maximum light output when the gamma radiation of about 10,000 photons/MeV, which is in two and a half times less than in the known scintillation crystals orthosilicate lutetium Ce2-xLu2(1-x)SiO5. Low efficiency of gamma radiation caused by the low density equal to just 3.8 g/cm3. This substance can be used to register the emission of neutrons, however, it is ineffective for gamma radiation.

Known litiisoderzhashchego scintillation substance crystal of the lutetium silicate with cerium, having the formula LiLuSiO4((M. E. Globus, B. C. Greene "Inorganic scintillators", ed. "ACT", Kharkov, (2000), page 51)). Crystal, doped with 1% CE3+has a maximum peak luminescence at 420 nm, time constant luminescence equal to 42 nanoseconds, and the maximum light output when registrationinfo lutetium Ce2-xLu2(1-x)SiO5. However, a significant drawback of this crystal is the low density of 5.5 g/cm3. This low density is not possible to use these crystals in 3-dimensional medical imaging (Fully-3D PET camera), and, especially, for MicroPET systems, as the most important requirement for scintillation crystal for these applications is the radiation length of the attenuation of gamma radiation (attenuation length), which must be less than 1.5 cm (W. M. Moses, S. E. Derenzo "Scintilators for positron emission tomography", Conference SCINT'95, Delft, The Netherlands (1995), LBL-37720). For a crystal with a density of 5.5 g/cm3this value is equal to 2.67 cm, while for crystal Ce2-xLu2(1-x)SiO5with a density of 7.4 g/cm3the radiation length is 1,14 see

Crystals Ce:LiYSiO4and Ce:LiLuSiO4may not be taken as a prototype for any of the variants of the present invention, since they are characterized as a chemical formula and crystal structure, which determines the density of the crystal. The high density of the crystal is the most important parameter for applications, which is the purpose of this invention.

The chemical formula of this invention are numerous crystals of solid solutions of na group B2/b, Z=4, and crystallizing in the hexagonal crystal system with the structural type of Apatite with space group P63/m, Z=1.

Known crystallizing in the structural type Apatite-britholite monocationic silicate of cerium CEwas 9.330,67(SiO4)6About2whereis a cation vacancies (Korovkin A. M., Merkuryeva T. I., Morozova L. G., Peschansky, I. A., Petrov, M. C., Savinova I. R. "Optical and spectral-luminescent properties of crystals orthosilicate lanthanides". Optics and spectroscopy, volume 58, issue.6, 1985, pp. 1266-1269), and a double silicate of cerium LiCe9(SiO4)6O2[monograph “Compounds of rare earth elements. Silicates, germanate, phosphates, arsenate, vanadates” / I. A. Bondar, N. In.Vinogradova, L. N. Demianets and others - M.: Nauka, 1983. - S. 288 (Chemistry of rare elements)]. In crystals Cewas 9.330,67SiO6O26and LiCe9Si6O26there is cerium, however, the luminescence of them completely extinguished, because of the concentration quenching due to high concentration of cerium ions. These crystals is absolutely not suitable for use as scintillate the CSOs silicate of cerium Cewas 9.330,67SiO6O26because he has the same symmetry, namely P63/m, Z=1, and the closest in composition to the substance of the above points. Analogous substances stated in paragraphs No. 19, No. 20 and No. 21 of the present invention is a crystal of a double silicate of cerium LiCe9Si6O26because he has the same symmetry P63/m, Z=1, and the closest in composition to the above options. As crystal Cewas 9.330,67Si6O26and crystal LiCe9Si6O26may not be taken as prototypes for any of the options scintillation substance of the present invention, because they are not of scintillation substance, i.e., do not have the generic concept of the present invention, a reflective assignment.

A computer search of chemical compounds in the database of the International X-ray library (PDF Database, International Center for Diffraction Data, Newton Square, PA, U. S. A.) showed that a known individual chemical compounds on the basis of monocationic and double silicates, Rwas 9.330,67(SiO4)6O2and LiR9Si6O26inania additional Legerova would cerium ions, what is necessary for the occurrence of scintillation properties. Therefore, connection Rwas 9.330,67(SiO4)6O2and LiR9Si6O26where R=La, Gd, or their mixture, should be considered as the application of known substances for a new purpose.

The closest analogue selected as the prototype for all cases of declared scintillation scintillation substance is a substance (options), patented in the patent of Russia №2157552 and U.S. patent 6278832. The chemical formula of this invention are numerous crystals of solid solutions on the basis of the crystal oxyorthosilicate, including cerium CE and crystallizing in the structural type Lu2SiO5with the space group B2/b, Z=4, the composition of which is expressed by a chemical formula CexLi1A1-xSiO5where a Is Lu, and at least one element from the group of Gd, Sc, Y, La, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb. Other elements of the periodic system may be present at the level of impurities in the source reagents or incorporated into the crystal during growth or annealing in a special atmosphere. Partially similar results are achieved in the patent school is-zYxSiO5where to 0.05<x<1,95 0.001<z<0,02. The principal disadvantage of the above inventions is the use for all patented scintillation substances only a single molar ratio 50% Lu2O3/50% SiO2=1 the source of oxides, which exactly corresponds to the stoichiometric composition Lu2SiO5. For all mixed crystals containing several rare-earth ions, was used in the ratio of 50% mixture of various elements and 50% SiO2. This ratio is not possible to grow large commercial (with a diameter of more than 80-100 mm) lateristriga crystals by the Czochralski method with a high uniformity of scintillation parameters around the scope of the bulls, which also crack when cut into scintillation elements, for example, the size of 0,8× 0,8× 10 mm Another significant disadvantage of scintillation substances is the presence of oxygen vacancies, which increase the light output and reduce the likelihood of cracking the bulls by sawing, but at the same time two to four times increase the intensity of the afterglow (thermoluminescence) after cessation of exposure to gamma radiation CSOs molar ratio of oxides 50% Lu2O3/50% SiO2is the information described in the U.S. patent 5660627. This patent protects a method of manufacturing a single crystal of orthosilicate lutetium by growing the crystal with a planar solidification front by the Czochralski method from a melt having the chemical formula Ce2xLu2(1-x)SiO5where 2× 10-4<x<6× 10-2. Spectra of gamma-ray luminescence of crystals grown with conical crystallization front and a flat front crystallization, have a very strong, dramatic differences in shape and position of the maximum. Such differences are related to the composition of the initial melt, which is the ratio of the main components of 50% Lu2O3/50% SiO2. Crystal growing from the melt, has a different composition, and there is a concentration gradient across the cross section of the crystal, and the actual ratio of ions Ce2xLu2(1-x)/Si differs from the ratio formula units 2/1. To confirm the stated goals in the patent 5660627 were grown crystals with a diameter of 26 mm and the speed of growing of 0.5 mm/h 1 mm/h, but even under these very favorable parameters of growing crystals grown with a tapered front may not be COI the Czochralski for many decades used for the commercial production of optical and piezoelectric materials, what is described in many hundreds of publications in journals and books. Well-known commercial lithium niobate crystal (R. L. Byer, J. F. Young. "Growth of High-Quality LiNBO3Crystals from the Congruent Melt". Journal of Appl. Phys. 41, n 6, (1970), p.2320-2325) grown by the Czochralski method from a congruent melt Licontains 0.946NbO2.973with the ratio of the source of oxides of Li2O/Nb2O5=contains 0.946, which is substantially different from conventional chemical reagent LiNb3with a ratio of 50% LiO/50% Nb2O5(P. Lerner, C. L Legras, J. Dumas. "Stoechiometrie des mohocristaux de metaniobate de lithium", Journal of Crystal Growth, 3,4 (1968) p.231-235). The existence of non-stoichiometric compounds is directly associated with the real structure of the crystal, which can be free (vacancy) lattice sites, and the internodes may be redundant atoms of one component (geld P. C., F. Sidorenko A. “correlation of physico-chemical properties of non-stoichiometric compounds from the structure of short-range order”. WPI. An SSSR, ser. Inorganic materials, 1979, T. 15, No. 6, pp. 1042-1048). As a result, the ratio of the components constituting the structure does not match the integer index, and the chemical formula of such compounds contain fractional numbers. Congruent calls the E. physical and mechanical properties remain constant throughout the volume of a large bull, grown by Czochralski method. For some applications, preferably using a composition close to the stoichiometric ratio of Li2O/Nb2O5=1, which is the essence of U.S. patent V from 15.10.2002.

This patent clearly shows how small changes in the composition of the crystal lead to significant changes in physical properties of the crystal, and this is important for practical applications.

Search congruent composition or composition, very close to him, is an important stage in the development of commercial production of all optical materials, however, the authors of this patent is not known publications in scientific journals or patents on congruent (or close to it) the composition for oxyorthosilicate lutetium. All known publications have been devoted to crystals in which the ratio of formula units (Ce2x+Lu2(1-x))/Si exactly equal to 2/1.

Summarizing the above, we can conclude that significant technical disadvantage inherent in the known as scintillation crystals based orthosilicate lutetium CexLu2-xSiO5and crystals prototype, and methods of producing these crystals, is the heterogeneity of the optical accessoriesyou boules, grown by Czochralski method, and from boules to bule, grown under the same conditions and, finally, slow growing. Largely these deficiencies caused by using Czochralski method the initial melt composition, which is characterized by the ratio formula units (Ce+Lu)/Si, is exactly equal to 2/1, i.e. the reason for these shortcomings is not congruent composition of the melt. In the presence of congruent points, but with the growth of the stoichiometric composition of the melt, the distribution coefficients as main components (Lu, Si), and impurities CE, differ from unity, moreover, as far as pulling the crystal structure of the crystal is shifted farther from the congruent point, which leads to a sharp deterioration of its quality, despite the extremely low rate of crystallization. The distribution coefficient of the component is the ratio of the number of the component in the melt to the quantity of the component in the crystal. Another common technical disadvantage of scintillation crystals based on orthosilicate lutetium are large losses of crystalline material due to cracking, when cutting large Boule diameter 60 mm plate thickness of about 1 mm, which in turn Ratkov thousand pieces, necessary for the production of a single scanner.

The essence of the invention.

The objective of the invention is the creation of new scintillation substance and method of its production. This invention is directed to solving the problem of serial production by the method of directional solidification of large crystal boules of scintillation substance having a high density, high light output and uniformity of scintillation parameters for mass production, reducing the cost of the finished scintillation elements due to small losses of crystalline substances by mechanical processing, reducing the time and intensity of the afterglow elements using optimum chemical composition of the crystals. Method Stepanova allows to obtain scintillation substances in the form of crystalline rods with the specified size, including a square cross-sectional shape, and therefore, to avoid the expensive operation of sawing a solid crystal. The method of obtaining scintillating substances in the form of a translucent or transparent ceramics in the form of rectangular rods and plates also eliminates costly loss scintillating veppu inventions and provides several technical results on the basis of different options scintillation substances, as crystals and ceramics having a high density and represents a rare earth silicates with different chemical formulas.

The technical problem to be solved by the proposed group of inventions is to obtain high light output luminescence throughout the volume of the large crystal boules grown by the method of directional solidification, in particular the methods of kyropoulos method and the Czochralski method, as well as ensuring the reproducibility of the scintillation properties of as-grown single crystals for mass commercial production.

The first technical problem in concrete forms is the composition of scintillation substance having the intensity and time of the afterglow less than in the known crystal orthosilicate lutetium in the presence of high their light yield comparable to their light yield of orthosilicate lutetium.

The second technical problem in the specific forms of implementation is a small percentage of losses of valuable scintillation substances due to cracking during cutting and the manufacture of scintillation elements for three-dimensional positron-emitting tomography (PET). In particular, for medical devices with ultra-high spatial resolution, for example, the emission of a positron-emitting isotopes, in living biological objects (MicroPET).

The third technical problem in concrete forms is a method of growing scintillation single crystals by the method of directional solidification. The term "directional solidification" means any method of obtaining a single crystal, including the method Czochralski, kyropoulos method, Bridgman method and other known methods.

These tasks are carried out on the basis of ten variants of the substances covered by the General structural and chemical formulas, and how to obtain these substances.

Option number 1. The known scintillation substance based on a silicate containing lutetium Lu and cerium CE, new in the first embodiment of the present invention is that the composition of a substance in the form of a single crystal expressed by the chemical formula

CexLu2+2y-xSi1-yO5+y,

x - 1× 10-4F. ed. to 0.02 F. ed.,

y - from 0,024 F. ed. up to 0,09 F. ed.

Technical problem-specific forms of implementation for the first variant is the scintillation substance, characterized in that it has the appearance of a single crystal having a composition expressed by a chemical formula

CexLu2,076-xSi0,962O5,038,

the treatment of the scintillation crystal, a new method of obtaining the scintillation crystal is that the growing of the single crystal directional solidification is produced from a melt made from the charge composition, characterized by the molar ratio of oxides 51.9% of (Lu2About3+CE2O3)/48.1% in SiO2.

Specific forms of implementation of this technical problem, the method of obtaining the scintillation crystal is growing a single crystal by Czochralski method, and the crystal is grown by the kyropoulos method, new in this method is that growing a single crystal by Czochralski method, and using the kyropoulos method is produced from a melt made from the charge composition, characterized by the molar ratio of oxides 51.9% of (Lu2About3+CE2About3)/48.1% in SiO2=1,079, this so-called congruent composition. Only with such a ratio of oxides composition of the grown crystal is equal to the composition of the melt, this circumstance makes it possible to grow crystals, a more uniform composition and physical characteristics than the crystals grown from the melt of stoichiometric composition 50% (Lu2About3+CE2About3)/50% SiO2. The crystal growth of the races is here scintillation elements.

Option number 2. The known scintillation substance based on a silicate containing lutetium Lu and cerium CE, in the second embodiment of this new invention is that the substance has a composition expressed by a chemical formula

CexLu2+2y-x-zAzSi1-yO5+y,

where a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb;

x - 1× 10-4F. ed. to 0.02 F. ed.;

y - from 0,024 F. ed. up to 0,09 F. ed.;

z - 1× 10-4F. ed. 0.05 F. ed.

Technical problem-specific forms of implementation for the second variant is the scintillation substance, characterized in that it has the appearance of a single crystal having a composition expressed by a chemical formula

CexLu2,076-x-zAzSi0,962O5,038,

where a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb;

x - 1× 10-4F. ed. to 0.02 F. ed.;

z - 1× 10-4F. ed. 0.05 F. ed.

Specified technical task specific forms of execution for the second variant is a scintillation substance, characterized in that it has the appearance of a single crystal having a composition expressed by a chemical formula

CexLu2,076-x-m-nLamYnSi0,962O5,038,

x - 1× 10-42O3+A2O3+Ce2O3)/48.1% in SiO2where A - no, at least one of the elements of the group Gd, Sc, Y, La, Eu, Tb.

Specific forms of implementation of this technical problem, the method of obtaining the scintillation crystal is growing a single crystal by Czochralski method, and the crystal is grown by the kyropoulos method, new in the way of obtain is that the growing single crystal by Czochralski method, and using the kyropoulos method is produced from a melt made from the charge composition, characterized by the molar ratio of oxides 51.9% of (Lu2About3+A2About3+CE2About3)/48.1% in SiO2where a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb.

Option number 3. The known scintillation substance based on a silicate containing lutetium Lu and cerium CE, in the third embodiment of this new invention is that the substance contains lithium Li in a quantity not exceeding 0.25 F. ed., and with the 0-4F. ed. to 0.02 F. ed.;

y - from 0,024 F. ed. up to 0,09 F. ed.;

q - 1× 10-4F. ed. to 0.2 F. ed.

R - 1× 10-4F. ed. 0.05 F. ed.

Technical problem-specific forms of implementation for the third variant is a scintillation substance, characterized in that it has the appearance of a single crystal containing lithium in an amount not exceeding 0.25 F. ed., and having a composition expressed by a chemical formula

CexLiq+pLu2,076-p-xSi0,962O5,038-p,

x - 1× 10-4F. ed. to 0.02 F. ed.;

q - 1× 10-4F. ed. to 0.2 F. ed.;

R - 1× 10-4F. ed. 0.05 F. ed.

Another technical challenge for the third variant is a method of obtaining a scintillation crystal, a new method of obtaining the scintillation crystal is that the growing of the single crystal directional solidification is produced from a melt made from the charge composition, characterized by the molar ratio of oxides 51.9% of (Lu2O3+Li2O+Ce2O3)/48.1% in SiO2.

Option number 4. The known scintillation substance based on a silicate containing lutetium Lu and cerium CE, in the fourth embodiment of this new invention is that the substance contains l the ub>2-p+2y-x-zAzSi1-yO5+y-p,

where a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb;

x - 1× 10-4F. ed. to 0.02 F. ed.;

- from 0,024 F. ed. up to 0,09 F. ed.;

z - 1× 10-4F. ed. 0.05 F. ed.;

q - 1× 10-4F. ed. to 0.2 F. ed.;

R - 1× 10-4F. ed. 0.05 F. ed.

Technical problem-specific forms of implementation for the fourth option is a scintillation substance, characterized in that it has the appearance of a single crystal containing lithium in an amount not exceeding 0.25 F. ed., and having a composition expressed by a chemical formula

CexLiq+pLu2,076-p-x-zAzSi0,962O5,038-p,

where a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb;

x - 1× 10-4F. ed. to 0.02 F. ed.;

z - 1× 10-4F. ed. 0.05 F. ed.;

q - 1× 10-4F. ed. to 0.2 F. ed.;

R - 1× 10-4F. ed. 0.05 F. ed.

Another technical challenge for the fourth option is a method of obtaining a scintillation crystal, a new method of obtaining the scintillation crystal is that the growing of the single crystal directional solidification is produced from a melt made from the charge composition, characterized mol/p>

Option # 5. The known scintillation substance based on a silicate containing lutetium Lu and cerium CE, in the fifth embodiment of this new invention is that the composition of a substance expressed by a chemical formula

CexLuwas 9.33-x0,67Si6O26,

x - 1× 10-4F. ed. to 0.1 F. ed.

Option # 6. The known scintillation substance based on a silicate containing lutetium Lu and cerium CE, in the sixth embodiment of this new invention is that it contains lithium Li, and the composition of a substance expressed by a chemical formula

CexLiq+pLuwas 9.33-x-p0,67Si6O26-p,

x - 1× 10-4F. ed. to 0.1 F. ed.;

q - 1× 10-4F. ed. to 0.3 F. ed.;

R - 1× 10-4F. ed. to 0.25 F. ed.

Option # 7. The known scintillation substance based on a silicate containing lutetium Lu and cerium CE, in the seventh embodiment of this new invention is that it contains lithium, and the composition of a substance expressed by a chemical formula

CexLiq+pLuwas 9.33-x-p-z0,67AzSi6O26-p,

where a is at least one element of group Gd Sup> F. ed. to 0.25 F. ed.;

z - 1× 10-4F. ed. to 8.9 F. ed.

Option # 8. The known scintillation substance based on a silicate containing lutetium Lu and cerium CE, in the eighth embodiment of this new invention is that it contains lithium Li in a quantity of one formula unit and the composition of a substance expressed by a chemical formula

CexLiLu9-xSi6O26,

x - 1× 10-4F. ed. to 0.1 F. ed.;

Option # 9. The known scintillation substance based on a silicate containing lutetium Lu and cerium CE, in the ninth embodiment of this new invention is that it contains lithium Li in a quantity of more than one formula unit and the composition of a substance expressed by a chemical formula

CexLi1+q+pLu9-x-pSi6O26-p,

x - 1× 10-4F. ed. to 0.1 F. ed.;

q - 1× 10-4F. ed. to 0.3 F. ed.;

R - 1× 10-4F. ed. to 0.25 F. ed.

Option number 10. The known scintillation substance based on a silicate containing lutetium Lu and cerium CE, in the tenth embodiment of this new invention is that it contains lithium Li in a quantity of more than one formula unit, and the composition of a substance expressed by a chemical formula

CexLi1+q+pLu9-x-p-zAz

q - 1× 10-4F. ed. to 0.3 F. ed.;

R - 1× 10-4F. ed. to 0.25 F. ed.;

z - 1× 10-4F. ed. to 8.9 F. ed.

For all these variants, the presence of cerium ions CE3+a mandatory feature, as scintillation under gamma and x-rays associated with luminescence in the transition 5d2F5/2in Jonah CE3+. Moreover, for all kinds of substances, the maximum luminescence in ion CE3+that fall within the range of blue light 410-450 nm. This range is optimal for the registration of radiation through both the photomultiplier-tubes, and semiconductor detectors. For this range using conventional, commercial photomultipliers radiation entrance window made of cheap glass that reduces the cost of the medical instrument relative to the scintillation crystal having a peak emission in the ultraviolet region of the spectrum. Also the hallmark for all option is the high quantum yield of luminescence of cerium ions in the crystals with chemical formulas that you specified earlier. Quantum yield (5%-9%) reflects sootnoshenie thermal energy vibrations of lattice atoms (91-95%). The most important scintillation parameter light output is directly related to the concentration of cerium ions CE3+in substance (crystal). For all cases the lower bound concentration of cerium ions is accepted equal to 1× 10-4F. ed., as it is observed blue luminescence, and we can talk about the effect of scintillation, but can be used only for qualitative determination of the presence of ionizing radiation (gamma, x-ray), but such small concentrations cannot be used in the real technical and medical devices. For practical application necessary crystals with higher concentrations of cerium ions, which have a much greater light output. On the other hand, a very high concentration of cerium ions lead to several negative results. First, the growth of crystals with high concentrations leads to deterioration of the optical quality of the crystals and the emergence of centers of light scattering. Secondly, there is a reduction in light output as the quality of the crystal, and by decreasing the quantum efficiency when the neighboring ions of cerium begin to interact with each other, the effect of concentration quenching LUMIN the Gonia, structural type CexLn2-xSiO5with the space group B2/b, Z=4. For substances CexLnwas 9.33-x0,67SiO26and CexLiLn9-xSiO26, crystallizing in the hexagonal crystal system, the structural type of Apatite with space group P63/m, Z=1, there is a limit of 0.1 F. ed. These limits are determined experimentally. If these limits are exceeded in the crystal growth process leads to the formation of numerous centers of light scattering and, therefore, the use of these defective crystals in medical and technical devices is not possible.

For options №1, №2, №3 and №4 important common characteristic of which is the ratio of the rare earth ions and silicon ions in the chemical composition of the crystal, namely that the composition characterized by the ratio formula units (Lu2-x+2y+Cex)/Si1-yand (Lu2-x+2y-z+Cex+Az)/Si1-ydiffers from a ratio of 2/1, which is exactly two, for all previously known scintillation substance based orthosilicates. For crystals of the present invention the ratio formula units (Lu2-x+2y+Cex)/Si1-yand (Lu2-x+2y-z+CEx+AzSi1-y2O3+CE2O3+A2O3)/48,8% SiO2=1,049 and 54,5% (Lu2O3+CE2O3+A2O3)/45.5% of SiO2=1,198, respectively. These values correspond to the compositions of the substances CexLu2+2y-xSi1-yO5+yCexLu2+2y-x-zAzSi1-yO5+yCexLiq+pLu2+2y-x-z-pAzSi1-yO5+y-pfor which the variable y varies from 0,024 F. ed. up to 0,09 F. ed. These values we have experimentally measured using a commercial instrument for electron microprobe (Cameca Camebax SX-50 working at 20 kV, 50 mA, and the beam diameter of 10 μm, the accuracy of determination of the composition of formula units amounted to ± 0,003 F. ed., in a molar percent -± 0,15 mol.%) on the mechanically polished samples of the crystals grown from the melt by means of directional solidification, which had the ratio (Lu2-x+Cex)/Si and (Lu2-x-y+Cex+Az)/Si in the range from 1.77 to 2,44. On the basis of x-ray studies and measurements of the melting temperature series powder compositions, the authors of this patent application was made part of the phase diagrams for the existence of oxyorthosilicate lutetium in the system Lu2O3+48,1% SiO2. The existence region of phase "S" surrounded by a field of two-phase equilibrium L+S, Lu2About3+S and S+Lu2Si2O7.

Chart (Fig.1) was adjusted for quasi-equilibrium conditions of crystallization during crystal growth from melts with different chemical composition. Comparison of the composition of the initial melt, which was set during the weighing of reagents, and the measured composition of the crystal grown from the melt, and the melt temperature in the growing crystal, showed that crystallization occurs in accordance with the lines of the liquidus and solidus shown in Fig.1. The crystal growth was carried out under low temperature gradients and velocities grow crystals of ~0.3 mm/h, which ensured the achievement of effective distribution coefficients of ions Lu3+and Si4+between the melt and growing the crystal in conditions close to equilibrium.

The liquidus line and stolzlechner ratio of the initial oxides Lu2About3and SiO2and it is in the range of molar percent to 44.5-50.5 per cent for SiO2and 55,5-49,5% Lu2O3. However, from a practical point of view, the interest is not the entire specified range, and this is demonstrated by three of the composition of the melt, indicated by arrows with numbers 1, 2 and 3. Arrow 1 indicates the composition of the initial melt with the content of the main components equal to 50% Lu2O3+50% SiO2. It should be emphasized that the composition of the crystal growing from the melt, the ratio of the main components of less than 50,9% Lu2O3/49,1% SiO2)=1,037. In order to grow the crystal composition ratio of the main components is exactly equal (50% Lu2O3/50% SiO2)=1, it is necessary to use the melt, the composition of the charge which is indicated by arrow 2, i.e. the ratio of the main components in the melt is approximately equal (46% Lu2O3+54% SiO2)=0,852.

The optimum composition of the mixture for growing quality of the scintillation crystal in the conditions of small temperature gradients (large diameter crucible) is the composition of the arrow 3. In this case, the distribution coefficients of the basic components equal to one, and the charge composition of the melt coincides with the composition ub>O3+48,1% SiO2)=1,079.

Thus, Fig.1. shows a clear solution of the technical problem in the specific forms of implementation of the first variant, describing scintillation substance for growing ultra-large single crystals using the kyropoulos method, and the cultivation of large crystals by the Czochralski method using the optimal composition of the starting oxides with a molar ratio of 51.9 percent (Lu2O3+CE2O3)/48.1% in SiO2while the compositions of the mixture of melt and the grown crystal are the same and are expressed by a chemical formula

CexLu2,076-xSi0,962O5,038,

x - 1× 10-4F. ed. to 0.01 F. ed.

Specific forms of implementation of scintillation substance stated in embodiments one through four, inclusive, is implemented in the form of a polycrystal/ceramics, and in the form of single crystal.

Method of preparation of ceramics by hot pressing, for example scintillation ceramics Gd2O(SiO4):Ce, described, for example, W. Rossner, R. Breu. "Luminescence properties cerium-doped gadolinium oxyortosilicate ceramic scintillators". Proc.Int.Conf. on Inorganic Scintillators and Their Application STINT'95, Netherlandds, Delft University, 1996, p.376-379).

In another method of preparation of the ceramic scintillator high optionscom is (where a is at least one of the elements of the group Gd, Sc, Y, La, Eu, Tb), the Council of Europe and the liquid SiCl4. The mixture of these components is added to an aqueous solution of ammonium hydrogen carbonate. Then the solution is washed, filtered and dried. After calcination at a temperature of 1400° With the mixture of oxides is mixed with the addition of a solvent and a low-melting additives, which contribute to the diffusion of atoms at grain boundaries during the final high temperature annealing. As additives can be used numerous compounds that do not affect the luminescence of cerium ions CE3+. After removal of the organic components and traces of water is pressing modified additives mixture in a hydrostatic press at a pressure of about 2000 atmospheres. Then, within a few hours, pressed ceramic blanks (rectangular or other shape) were annealed in vacuum at a temperature of 70-150° C below the melting temperature of this ceramic composition. To correct the color centers and improve the optical quality at the final stage of preparation should otjihase in oxygen-containing atmosphere. So, get a ceramic scintillator of poluprosracna comparison with single crystals: a significant reduction of the production technology of scintillators; the increased yield of the material (no cracks); because of the thickness of the diamond saw no 20-50% loss of expensive crystalline substances for thin elements; uniform distribution of impurity ions CE volume of the polycrystal; reduction of time of the production process; the giving of any desired shape to the product.

Specific forms of implementation to obtain scintillation substance in the form of a single crystal is used a method of directional solidification. New in this invention is a method of producing scintillation substances by means of directional crystallization is that the growing of single crystals of directional solidification is made from a melt made from the charge congruent compositions, which are characterized by a molar ratio of oxides 51.9% of (Lu2O3+CE2O3)/48.1% in SiO2for option No. 1, 51,9% (Lu2O3+A2O3+CE2O3)/48.1% in SiO2for option No. 2, 51,9% (Lu2O3+Li2O+CE2O3)/48.1% in SiO2for option No. 3 and 51.9% (Lu2O3+Li2O+A2O3+CE2O3)/48.1% in SiO2for option No. 4.

Specific features and parameters of vyrashivaniem particular by the Czochralski method, see the article C. D. Brandle, A. J. Valentino, G. W. Berkstresser. "Czochralski growth of rare-earth orthosilicates (Ln2SiO5), J. Crystal Growth 79 (1986), pp.308-315. In this publication, the ratio of the diameter of the crystal (d) to the diameter of the crucible (D) has a value of d/D=0,4, which corresponds to the optimum for Czochralski method. Also optimal for Czochralski method is the use of the crucible, in which the height (H) equal to its diameter (D=H).

Low temperature gradients are the principal feature of growing large crystals (diameter 80-150 mm) by means of directional solidification, in particular by the method of Kyropoulos of iridium crucibles diameter 100-180 mm, the optimal ratio of the diameter of the crystal (d) to the diameter of the crucible (D) has a value of d/D=0.7-0.9. Method of Kyropoulos widely used for commercial cultivation massive sapphire crystal (Al2O3), and for some alkali halide scintillation crystals. However, the authors of this patent is not known publication on the cultivation of rare earth silicates method of Kyropoulos. Methodology and distinctive method of Kyropoulos and Czochralski method described in detail in the book by K. T. Wilke "Growing crystals", Leningrad: Nedra, 1977, 600 C., the translation from German: von K. Th.Wilkem. After the start of the crystal growth process is razresevanje crystal in the form of a cone 6, and then there is the growing crystal 7 with a constant diameter. In Fig.2 presents a diagram of the process when using 100% of the initial substances for growing crystal. In Fig.3 presents a diagram of the process when using 70-90% of the initial substances for growing crystal, and as a result, the crucible remains a small amount of the substance 9. The optimal value for the diameter of the crucible (D), height (H), the initial level of the melt in the crucible (Hm), the diameter of the crystal (d) and the length of the cylindrical part of the crystal (h) are given by the relations

h=H+y, where y0.1 D

0,8 provides finding of the grown crystal in the crucible in the process of lowering the temperature, which is extremely important for uniform temperature reduction throughout the volume of large bulls in the process after growth annealing. Such arrangement of the crystal relative to the crucible is a fundamental difference kyropoulos method from Czochralski method, in which the grown crystal is located above the crucible in the process of lowering the temperature after separation of the crystal from the melt. The different position of the crystal leads to the fact that in the Czochralski method, the crystal is cooled in the conditions under which the top crystal boules has all the time the temperature is significantly lower than the lower part of the crystal located near a hot crucible. This leads to different contents of oxygen vacancies and the ratio of ions CE3+/CE4+the length of the crystal, which is one of the additional reasons why the scintillation crystals orthosilicate lutetium, grown by Czochralski method, there is a strong variation of parameters from boules to bule. All boules grown by the Czochralski method, have some differences in the properties of the length and diameter of the crystals, and this in combination with izgotovlennyh from different parts of the boules.

On the contrary, as shown by Fig.2 and Fig.3, when the annealing all the bulls inside of the crucible are achieved low temperature gradients in the process of annealing of the grown crystal. Practically, this delivery method allows to cool the crystals in conditions close to isothermal, when at any moment time all parts of the crystal boules are at approximately the same temperature. This is the basis to achieve constant light output in all parts of the large crystal grown by the kyropoulos method.

The choice of the lower and upper range values of the ratio of initial oxides Lu2About3and SiO2for variants substances №1, №2, №3 and №4 also illustrates Fig.1. The lower bound on the Lu number of ingredients in the crystal is defined molar ratio of the oxides of 51.2% (Lu2O3+CE2O3)/48,8% SiO2=1,049, which in chemical formula scintillation substance corresponds to the value of the variable y=0,024. The lower bound is determined by the accuracy of the chemical and physical experimental methods of measuring the amount of lutetium and silicon in the crystal. This accuracy allows to clearly distinguish between the chemical compositions of substances (crystals) of this invention from b>3)/50% SiO2.

The upper bound on the Lu number of ingredients in the crystal is defined molar ratio of the oxides of 54.5% (Lu2O3+CE2O3)/45.5% of SiO2=1,198, in which the chemical formula of a substance corresponds to the value of the variable y=0,09. This boundary was determined experimentally. In case of further increase in the content of Lu2O3in the initial melt and, consequently, in the crystal begin to appear centers of light scattering, which reduces the light output, and as a result the technical result of the present invention is not achieved. After recalculation of the lower and upper bounds for the first four options for the range of compositions can be defined through the ratio formula units (Lu2-x+Cex)/Si and (Lu2-x-y+Cex+Az)/Si, which varies from 2,077 to 2,396. These values correspond to compositions in the form of chemical formulas of the substances CexLu2+2y-xSi1-yO5+yCexLu2+2y-x-zAzSi1-yO5+yCexLiq+pLu2-p+2y-x-zAzSi1-yO5+y-pfor which the variable y varies from 0,024 F. ed. up to 0,09 F. ed.

You should pay special attention to the structures of crystals of solid solutions on the basis of oxyartes is limited by the maximum solubility of SiO2corresponds to the composition of solid solutions with a molar ratio of 49.5% Lu2O3/50.5% of SiO2=0,980, and the left boundary with a value of 50.9% Lu2O3/49,1% SiO2=1,037 is determined by the composition of the melt 50% Lu2O3+50% SiO2, Fig.1. Identify the structures of crystals can be grown by the method of crystallization from a melt made from the charge of stoichiometric composition 50% Lu2O3/50% SiO2=1,000, indicated by the arrow 1 in Fig.1. Depending on the specific technology, namely from thermal growing conditions, temperature gradients at the crystallization front, which is determined primarily by the diameter of the crystal, the distribution coefficients of the components can vary from 1 to equilibrium values, which in turn are determined in accordance with the state diagram, Fig.1. The result of the mixture of stoichiometric composition 50% Lu2O3+50% SiO2you can grow crystals whose composition will be in a range with a lower bound of relations component is more 49,5% Lu2O3/50.5% of SiO2=0,980 and the top border of the relationship component is less than the value of 50.9% Lu2O3/49,1% SiO2=1,037 that formula units soooon compositions of the crystals is not patented in known patents. However, it cannot be the object of the new invention, because the crystals having a composition within this range, fall under the concept of "existing technology". These crystals do not provide improvement of technical parameters in comparison with known substances. Growing crystals orthosilicate lutetium in this range requires the use of a composition of the melt, which is very different from the composition of the growing of the crystal. Therefore, the crystals in this range may present some interest for scientific research, however, these crystals will have a significant change in chemical composition along the length, as well as extremely strong change all physical and scintillation parameters as the length and diameter of the crystals, since the distribution coefficients of silicon and lutetium differ from one. In this regard, the commercial production of crystals of similar composition is not of interest - the percentage yield of the scintillation elements are low, the production cost is extremely high.

Scintillation substance described in the embodiments, No. 2, No. 4, No. 7 and No. 10, may isomorphic substitution of ions in the crystal of the lutetium at least one of the ions of the group of Gd, Sc, Y, La, Eu, Tb, p. However, the principal disadvantage of a significant expansion of the range of ion substitution on lutetium all of these ions is that this leads to a strong decrease of the density of the crystal, and consequently, to a sharp decrease in the efficiency of absorption of gamma rays, and as a result the reduction in light output. In addition, ions of Eu, Tb reduce the intensity of the luminescence in the blue region of the spectrum due to the redistribution of the energy radiated in the red region of the spectrum for europium, and in the green part of the spectrum for terbium. In the case of optimally chosen concentrations of ions of cerium, terbium and europium emission spectrum of the scintillation crystal occupies the entire range of visible light and is a white light. Scintillation substances such radiation spectrum more efficiently work with solid state receivers, as well as cheap silicon/germanium semiconductor receivers sensitivity is 2-3 times lower for the blue region of the spectrum in comparison with the green and especially red region of the spectrum. Not optically active ions of Gd, Sc, Y, La allow you to control the parameter of the crystal lattice and thus to grow crystals without mechanical stress reduces the operating expensive lutetium on cheap La, Gd, Y reduces the cost of scintillation substance.

Ionic radiisignificantly more ionic radiusIn the interaction of gamma-quantum with the lattice leads to the formation of a huge number of free electrons and holes, where these electrons were knocked gamma-quantum. In the subsequent recombination of electrons and holes are excited lattice, and this energy is transferred cerium ions, which emit in the blue region of the spectrum. Especially effective recombination on the optical centers where there are atoms with very different radii. For example, the replacement of part of the lutetium ions on lanthanum ions, having a significantly larger diameter leads to a dramatic increase in light output, which is further proved by the examples of specific substances, confirming the invention. In order recombination of electron-hole were the most effective, it is necessary to use small concentrations of isomorphic replacement of impurities. When large concentrate. Based on the above experimental data, we have chosen the range of the variable z - 1× 10-4F. ed. 0.05 F. ed. for variants substances CexLu2+2y-x-zAzSi1-yO5+yand CexLiq+pLuz-p+2y-x-zAzSi1-yO5+y-pwhere a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb. However, this range can be significantly extended to elements of Y and La, which at high concentrations is saved increased light output, despite the fact that the density of the crystals decreases. Therefore, the technical task specific forms of execution is a scintillation substance CexLu2,076-x-m-nLamYnSi0,962O5,038in which the value of the variable m does not exceed 0,05 F. ed., and the range of n is from 1× 10-4F. ed. up to 2 lb.ed.

For substances seventh and tenth variants with the General formula CexLiq+pLuwas 9.33-x-p-z0,67AzSi6O26-pand CexLi1+q+pLu9-x-p-zAzSi6O26-paccordingly, set the range of z - 5× 10-4F. ed. to 8.9 F. ed. To maintain a high density and a high light output preferred small concentration is considerably less density and light output with a sharp decrease in the value of the initial reagents, consequently, the cost of the crystal. Such crystals may be of interest for use in sensors in nuclear power plants, where the important parameters are the high radiation and chemical resistance in combination with low price. Such sensors must be in each room, so that you can determine the level of radiation without a human presence. Existing sensors on the basis of alkali-halide crystals are unreliable, because they are not able to work in conditions of high levels of radioactivity that are possible in the case of an emergency.

For options # 3 and # 4 important common characteristic of which is the presence of scintillation substance based on a silicate of lithium ions in an amount not exceeding 0.25 formula units, and Li in a quantity q of formula units located in the interstices of the crystal structure, the other part of lithium ions in the number R of formula units is in the lattice, replacing lutetium ions. A positive effect with the introduction of lithium ions in the interstices of the structure is achieved due to the fact that

(a) the introduction is accompanied by minimal changes of the crystalline structure of the substance;

(b) introduction of lithium ions ub>xLiq+pLu2-p+2y-xSi1-yO5+y-pand CexLiq+pLu2-p+2y-x-zAzSi1-yO5+y-pcontributes to the stabilization of cerium ions in the condition CE3+that significantly increases their light yield,

(C) the introduction of lithium ions leads to a change in conductivity (A. A. Wesman, K. I. Petrov. "Functional inorganic compounds of lithium". M: Energoizdat, (1996), 208 pages), which reduces the time of the afterglow of the substance Table.1.

For # 3 and # 4 available substances lower bounds p and q, the content of lithium ions are assumed to be 1× 10-4F. ed., as this limit lithium content in which we can observe the effect of increasing their light yield and reduce poslesvecheniya scintillation. The upper limit of the content of lithium ions in a scintillation substance is determined experimentally, when the total content of lithium ions, exceeding 0.25 formula units, the intensity of their light yield drops sharply due to the fact that excessively increasing the conductivity of the substance, and it scintillation substance unsuitable for industrial applications, PL. 1.

All scintillation substance based on a silicate declared first to fourth variants, inclusive, belong to the monoclinic crystal system, p the tenth inclusive, belong to another structure - type Apatite-britholite, space group P63/m, Z=1. Substances, as claimed in variation No. 6 and No. 7, share an important distinctive feature, namely they contain lithium, total (p+q) the upper limit of the content of which reaches 0,55 F. ed. The upper limit of q (where q indicates the number of implemented lithium, i.e., lithium, introduced in the interstices of the crystal lattice) to 0.3 F. ed. determined experimentally. With the introduction of lithium in the amount of more than 0.3 F. ed. the intensity of their light yield falls, the substance unsuitable for industrial applications. Choose the upper limit of the substitution of the rare-earth ion lithium p (where p stands for the number lithium, which replaces the rare-earth ion) to 0.25 F. ed due to the fact that patitapavana structure is preserved under substitution of atoms of rare-earth ions by lithium atoms only in large devotionto allowing distortion and deviation from perfect symmetry. In this second position of semiartinian always for rare earth elements. Lower bounds p and q, the content of lithium ions are assumed to be 1× 10-4F. ed., as this limit lithium content in which we can observe the effect of increasing the light is s set to 1.55V F. ed., because Apatite-britayeva matrix remains stable under a wide overrides the first position of the lithium ions. The substitution of a large number of underlying ions of cerium lithium and lutetium as in mononational and double cerium silicates with the structure of Apatite-britholite, which are analogues, can reduce the effect of quenching of the luminescence of cerium, and a new substance acquires scintillation properties.

Our experimental studies showed that the crystals CexLiR9-xSi6O26and Rwas 9.330,675Si6O26where R=La, Gd, grown by Czochralski method, have high optical quality, but much inferior crystals orthosilicate lutetium as density and light output. To improve critical scintillation parameters we have carried out the processes of growing the following crystals: Ce0,015LiGd2,985Lu6Si6O26; Ce0,015LiLa2,985Lu6Si6O26; Ce0,015LiGd5,985Lu3SiO6O26; Ce0,015LiLu8,985Si6O26Ce0,015Li0,45Lu8,935Si6O26Ce0,015Li0,12Gd2,985Lu6,330,67Si6O26Ce0,015Liof 0.25Gd2,985Lu6,280,67Si6O26Ce0,011Liof 0.25Y6,989Lu2,230,67Si6O25,9Ce0,011Li0,35Y3,989Lafor 0.9Lu3,330,67Si6O25,9Ce0,012Li0,05La3,988Lu5,330,67Si6O26. Numerous experiments in different modes of cultivation allowed to obtain these substances only in the form of polycrystals. Testing of polycrystalline composition Ce0,015LiLu8,985Si6O26showed that this new scintillation substance has similar parameters as density, light output, and the time constant of the scintillation with known crystal Ce:LSO.

To define the boundaries of the compositions of scintillation substance according to answers No. 6 and No. 7, which can be grown as a single crystal, we have tested the substances having the initial composition of the melt Ce0,012Lia 0.1Lu5,33La3,9880,67Si6O26; Ce0,012Liof 0.2Lu2,33La6,9880,67Si6O26; Ce0,015Li0,45Lu2,115Gd70,67Si6O25,8; Ce0,015Lia 0.1Lu7,31Y20,67Si6O25,95; Ce0,015Li0,28Lu7,815Eu1,50,67Si6O26. All these compounds were obtained in the form of single crystals, or semi-transparent or white opaque polycrystalline ingots. For example, the use of melt chemical composition Ce0,015Li0,55Lu1,065La80,67Si6O25,75and the speed of pulling the growing crystal 2.5 mm/hour allows you to grow from the melt of the crystal with the chemical composition Ce0,003Li0,55Lu1,327La80,67Si6O26. The increase in the rate of extrusion and gradient at the crystallization front allows you to get a new crystal scintillation substances in the range of compositions from Ce0,003Li0,55Lu1,077La80,67Si6O25,75to Ce0,015Li0,55Lu1,065La80,67Si6O26-pwhere the variables q and p is not more than 0.3 F. ed. and 0.25 F. ed., accordingly, z varies from 5× 10-4to 8.9 F. ed.

To define the boundaries of the compositions scintillating substances variants No. 9 and No. 10, which can be grown as a single crystal, we have tested the substances having the initial composition of the melt Ce0,015LiLu8,985Si6O26; Ce0,015Li1,55Lu8,735Si6O25,75; Ce0,015Li1,05Lu8,985Si6O26; Ce0,015Li1,3Lu1,785La7Si6O25,8; Ce0,015Li1,4Lu6,885Y2Si6O25,9; Ce0,015Li1,2Lu2,885Gd6Si6O25,9. All these compounds were obtained in the form of single crystals, or semi-transparent or white opaque polycrystalline ingots. For example, the use of melt chemical composition Ce0,015LiLu8,985Si6O26and the speed of pulling the growing crystal of 0.5 mm/hour allows you to grow from this melt the single crystal with the chemical composition Ce0,003LiLu8,997Si6O26. The increase in the rate of extrusion and gradients on the front crystallizatio8,997Si6O26to Ce0,015Li1,55Lu8,735Si6O25,75. Summarized this new scintillation substance (options # 9 and # 10) has the following chemical formula: CexLi1+q+pLu9-x-p-zAzSiO26-pvariables q and p is not more than 0.3 F. ed. and 0.25 F. ed., accordingly, z varies from 5× 10-4to 8.9 F. ed.

We conducted x-ray study of powdered crystalline samples CexLiq+pLu9-x-pSi6O26-pon the x-ray diffractometer. The analysis of the obtained diffraction patterns shows that the single crystal CexLiq+pLu9-x-pSi6O26-pcrystallize in the hexagonal crystal system and can be attributed to the structural type of Apatite-britholite LiLu9[SiO4]6O2with the space group P63/m, Z=1. Indicated by the diffraction pattern of the crystal Ce0,003LiLu8,997Si6O26presented on Fig.4. Using all 35 reflections from planes at angles of reflection 2in the range from 15 degrees to 60 degrees, we have calculated the parameters of the crystal cell, which amounted toandExperimental study of the dependence of the time constant of decay of scintillations (, NS), and the light output in the field of 410-450 nm depending on the chemical composition of the crystals was carried out using radiation, radionuclide60With analogously to the method described in [E. G. Devitsin, V. A. Kozlov, S. Yu.Potashov, A. I. Zagumennyi, Yu.D.Zavartsev. "Luminescent properties of Lu3Al5O12crystal doped with Ce. Proceeding of International Conferences "Inorganic scintillators and their applications (SCINT 95), Delft, the Netherlands, Aug.20-1 Sep. 1995]. The results of the measurements are presented in Table 1.

The measurement of the intensity and lie to the duration of the afterglow of the reference sample after exposure to gamma-rays and ultraviolet irradiation were the same. Therefore, the systematic measurements were used to install with UV excitation. The luminescence of the samples was instituted standard ultraviolet lamp (power: 12 watts for 60 minutes, after turning off the lamp intensity is reduced residual fluorescence within 120 min was detected by a photomultiplier tube PMT-100 or the photodetector PD-24K connected to the oscilloscope Tektronix TDS 3052 and the multimeter Agilent 34401A connected to the computer. Changes in the intensity of samples with strong afterglow is well described by an exponential dependence, in which the intensity decreases 2.72 times with a time constant of about 25-35 minutes, these samples remained significant fluorescence over 180 minutes. Samples with low afterglow describes the dependence with a time constant of several tens of seconds. After turning off the lamp for some samples the effect of the afterglow was observed. The test results of the samples on the effect of the afterglow are presented in Table 1.

The essence of the proposed technical solution is illustrated in the following graphic material.

Fig.1. Plot the phase diagram in the system Lu2About3- SiO2.

Fig.2. The scheme of the optimal size Krista is ramulosa for crystallization only part of the melt.

Fig.4. The diffraction pattern of the crystal Ce0,003Li1,08Lu8,947Si6O25,95.

All crystals were grown and studied in the course of work on this patent, were grown from iridium crucibles with the use of highly pure chemicals with the content of the main substance of 99.99% and 99.999%.

Example 1. The cultivation of the well-known "reference" crystal Ce:Lu2SiO5for which the ratio Lu/Si=2, and the crystal is grown with respect to (Lu+Ce)/Si=2,061 (y=0,015), which is outside the range of compositions option No. 1 of the present invention.

Because of the strong variation of the parameters of the crystal in various publications for the most reliable data can be accepted parameters of commercial crystals Ce:Lu2SiO5. The highest light output demonstrate crystals having a concentration of cerium ions, equal to 0.12 at.% (or about 0,002 F. ed.). These crystals have a chemical formula Ce0,002Lu1.998SiO5. Taking into account the distribution coefficient of cerium ions between the melt and the growing crystal, is approximately k=0.2, the crucible should download the source material with the concentration of cerium equal to about 0.6 at.% (or formula units 0,012 F. ed.). The ratio of the initial oxides Lu2SiO5by the Czochralski method under conditions of high temperature gradients (Experiment 1) and at low temperature gradients (Experiments 2 and 3).

Experiment 1 (non-equilibrium conditions, the composition of the charge 50% (Lu2O3+Ce2O3)/50% SiO2). The growing crystal was obtained from the iridium crucible with a diameter of 40 mm with negligible thermal insulation in a protective atmosphere of argon (100 volume% Ar), with a growth rate of 3.5 mm/h and the frequency of rotation of 15 rpm, the Original charge, from the melt which was growing crystal, had a chemical composition Ce0,012Lu1,998SiO5. In these conditions has grown crystal with a diameter of 16 mm and a length of 54 mm, which is in the upper part of the bulls did not contain centers of light scattering and was colorless, in the lower part of boules crystal cracked. Using a commercial device for electron microprobe was measured content of cerium, lutetium and silicon in the crystal. The chemical composition in the upper conical part of the obtained crystal is expressed by the formula Ce0,002Lu1,998SiO5for which the ratio (Lu+Ce)/Si exactly equal to two, possibly wifi Manager less than two. For making standard used only the upper conical part of the boules. The parameters of the reference crystal are shown in Table 1.

Experiment 2 (equilibrium conditions, the composition of the charge 50% (Lu2O3+CE2O3)/50% SiO2). The growing crystal was obtained from the iridium crucible with a diameter of 40 mm with good heat insulation in a protective argon atmosphere (of 99.5 volume% Ar+0.5% of the volume O2), a growth rate of 2 mm/h and the frequency of rotation of 15 rpm, the Composition of the original mixture had a chemical composition Ce0,012Lu1,998SiO5. In these conditions it was grown crystal with a diameter of 18 mm and a length of 45 mm, which did not contain centers of light scattering and was colorless. Using a commercial device for electron microprobe was measured content of cerium, lutetium and silicon in the crystal. The chemical composition of the upper part of the obtained crystal reflects the formula Ce0,003Lu2,027Si0,985O5,015for which the ratio (Lu+Ce)/Si=2,061. For the bottom of the crystal, the higher the concentration of cerium, and less than (Lu+Ce)/Si=2,061. Obviously, this crystal can not be used as a reference, since its composition differs from that of known crystals Lu2-xCexSiO5.

Etrali of the iridium crucible with a diameter of 40 mm with good heat insulation in a protective atmosphere (of 99.5 volume% Ar+0.5% of the volume O2), a growth rate of 2 mm/h and the frequency of rotation of 15 rpm In accordance with the arrow 2 in Fig.1 you must use the original part of the 46% (Lu2O3+Ce2O3)/54% SiO2, which corresponds to the melt chemical composition Ce0,012Lu1,828Si1,080O4,920. In these conditions it was grown on the crystal length of 52 mm and a diameter of 16 mm, which was colorless, but with a light scattering centers, the number of which has increased to the bottom of the boules. Using a commercial device for electron microprobe was measured content of cerium, lutetium and silicon in the upper part of the grown crystal. The chemical composition of the obtained crystal is in the range from Ce0,0022Lu1,997Si1,0O5(top Buli) to Ce0,0028Lu1,968Si1,010Oto 4.98(bottom boules).

Comparison of scintillation parameters of the two samples obtained in experiments 1 and 3 showed that they have approximately the same light output when gamma excitation, and both samples show approximately the same time luminescence (attenuation scintillations)=43 NS.

Example 2. Confirmation of the invention in specific forms of implementation of the method of obtaining scintillation the large single crystals using the kyropoulos method, as the charge was used, the optimum composition of the starting oxides with a molar ratio of 51.9 per cent (Ce2O3+Lu2O3+A2O3+Li2O)/48.1% in SiO2while the composition of the melt and crystal expressed by the chemical formula CexLiq+pLu2,076-p-x-zAzSi0,962O5,038-pwhere a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb, x is in the range of 1× 10-4F. ed. to 0.02 F. ed., z is not more than 0.05 F. ed., q+p is not more than 0,025 F. ed.

For automated installation with the weighing system of the crystal, the crystal is grown with a diameter of 78 mm was obtained from the iridium crucible inner diameter of 96 mm and a height of 112 mm, surrounded optimum thermal insulation. Filling the crucible with a mixture of initial reagents and the growing crystal was carried out in flowing protective atmosphere (99.7% of the volume of N2+0,3% volume O2). Initial loading of the crucible source reagents was 4400 grams. The composition of the original mixture had a chemical composition CexLu2,076-xSi0,962O5,038, i.e. characterized by a molar ratio of oxides 51.9% of (Lu2About3+CE2O3)/48.1% in SiO2. As the seed crystal was used monocrystalline crucial is shivanie conical part of the crystal from the seed crystal to the diameter of 78 mm occurred over a length of 5 to 25 mm, after that was grown cylindrical portion of constant diameter. The growth process was ended by increasing the rate of withdrawal, after the mass of the crystal has reached 90% by weight of the boot. The moment of separation of the solidification front from the bottom of the crucible with the remnants of the melt was recorded by the weighing system of the crystal. Annealing of the crystal produced by lowering the temperature to room for 30 hours. In these conditions it was grown crystal weighing 3910 grams and a length of 12.5 see Because of this technology in the crucible virtually no melt, which is usually during solidification causes swelling of iridium crucible. The effect of inflating the crucible can occur if the melt during cooling is more than 20% of the volume of the crucible. Swelling of the crucibles dramatically reduces the time of operation is extremely expensive iridium crucibles, and therefore, greatly increases the cost of the crystal Boule.

Received Buhl was used to measure the percentage of losses crystalline substance when it is cut into thin elements and rejection at the intermediate stages due to the presence of chipping or breaking into pieces. The second type of loss is generated due to the thickness of the saw with a diamond saw, but they are always exactly known, since the ICS of 78 mm and a thickness of 11 mm was carried out with a diamond saw with the inner cutting edge and a disk thickness of 0.6 mm After this operation received 9 plates, which did not contain cracks or chips. For this stage losses amounted to 0%. In the second stage, the obtained plates were cut in a perpendicular direction to the plate thickness of 1 mm using a diamond saw with the inner cutting edge and a disk thickness of 0.2 mm For the phase loss due to cracking was ~1%. In the next step, the plates were glued together and cut to size rods 1× 1× 11 mm At this stage, the loss amounted to about 3%. At the final stage, the rods are glued together into blocks, each of which contained about 30× 30 rods, and implemented mechanical polishing one or both ends of the scintillation elements. At this stage loss would not exceed 0.1%. Thus, the total loss due to cracking was about 4%.

For comparison of the crucible with a diameter of 100 mm and a height of 100 mm was grown by Czochralski method known crystal Ce:Lu2SiO5diameter of 50 mm and a length of 105 mm from the melt with the original chemical composition Ce0,012Lu1,998SiO5. When sawing boules on a plate with a diameter of 50 mm and a thickness of 11 mm from 8 cut plates 3 plates had wavy cracks. In the manufacture of the rods s and cracking to pieces, approximately 32%.

On the same technological scheme grew and cut crystal compositions CexLi0,08Lu2,026-xSi0,962O5,008-pCexLi0,02Lu2,072-xSi0,962O5,034CexLu2,066-x-zLa0,962Si0,962O5,038CexLu2,036-xY0,04Si0,962O5,038CexLiof 0.2Lu2,006-xGd0,04Si0,962O5,018CexLiof 0.15Lu2,071-x-zTbzSi0,962O4,988with different content of cerium x - 1× 10-4F. ed. to 0.02 F. ed.

The chemical compositions of the melts proposed in this invention, and the crystal is grown by the kyropoulos method allows to drastically reduce the loss of single-crystal scintillation substances during sawing large crystal boules.

Example 3. A method of obtaining a scintillation substance in the form of scintillation ceramics based on zirconium silicate lanthanum and lutetium, characterized in that as starting materials for the preparation of the charge used aqueous solutions of chlorides Lu, La, CE and liquid SiCl4the mixture is prepared from the mixture composition, characterized by the molar ratio of oxides 51.9% of (Lu2O3+La2O3+CE2O3)/48.1% in SiO23+. Our research has shown that small additives of ions of Li, Na, K, Cs, Be, B, F, Al, S, Cl, Zn, Sc, Ga, Ge, Se, Br, In, Sn, I not lead to a decrease in light output of the scintillation ceramics. Small additions of ions of SB, P, CA, Ti, V, Cr, Mn, Fe, Co, Mi, As, Sr, Zr, Nb, Mo, Cd, Sb, Ba, Hf, TA, W, Pb, Bi reduce or completely suppress the luminescence of cerium. The additive compounds of lithium, for example LiCl, Li2GeF6, Li2GeO3, Li3IN3,instrumental in obtaining the scintillation ceramics high optical quality. After removal of the organic components and traces of water are two possible ways of synthesis of ceramics.

The first method. The mixture with the addition of Li2GeO3, Li3IN3is placed in the capsule of thin platinum sheet, is pumped by a vacuum pump, and the hole is sealed by a gas burner. Then is SIGRE 1300° C for 2 hours.

The second method. The mixture with the addition of LiCl, Li2GeF6, Li2SEO3, Li3BO3have merged into a hydrostatic press with a pressure of 2000 atmospheres. Then, within a few hours, pressed ceramic blanks (rectangular or other shape) were annealed in vacuum at a temperature of 1700-1840° C. To eliminate the purple color centers and improve the optical quality at the final stage of the billet was annealed in air at a temperature of 1300° C for 24 hours. As a result of these transactions have received the finished product of the scintillator ceramic, coated with a thin white layer with all the mountains. Polishing one face of the ceramic product gives immediately ready scintillation element with a white reflective coating on all other sides. The items produced by this method can be applied in x-ray computed fluoro.

Example 4. Scintillation substance based on a silicate containing lutetium Lu and cerium CE, characterized in that the composition of a substance in the form of a single crystal expressed by the chemical formula CexLu2+2y-x-zAzSi1-yO5+ywhere a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb, x - 1× 10-40,002Lu2,044Tb0,03Si0,962O5,038used original reagents (Lu2O3, b2O3CeO2, SiO2) purity 99,995%. The growing crystal was obtained from the iridium crucible with an inner diameter of 54 mm and a height of 54 mm containing a melt of a composition characterized by the molar ratio of oxides 51.9% of (Lu2O3+CE2About3+b2O3)/48.1% in SiO2. The rate of extrusion was 3 mm/h, rotation speed of 15 rpm, the crystallization Process was carried out in a protective atmosphere of argon (of 99.5 volume% Ar+0.5% of the volume O2). Crystal with a diameter of 26 mm and a length of the cylindrical part 55 mm had a high optical quality and did not contain light scattering centers. Polished samples of this crystal were used to measure parameters, which are presented in Table 1.

The growing Czochralski crystal orthosilicate lutetium-lanthanum-cerium with the chemical composition Lu2,1La0,02Ce0,0015Si0,94O5,06was obtained from the iridium crucible with an inner diameter of 36 mm and a height of 38 mm, containing a melt of a composition characterized by the molar ratio of oxides 51.9% of (Lu2O3+Ce2O3+La2O3)/48.1% in the United ILSA in a protective argon atmosphere (of 99.5 volume% Ar+0.5% of the volume O2). Crystal with a diameter of 17 mm and a length of the cylindrical part 20 mm had a high optical quality and did not contain light scattering centers. Polished samples of this crystal were used to measure parameters, which are presented in Table 1. Similar conditions for growing crystals were used for all experimental samples, the parameters of which are presented in Table 1.

Example 5. Confirmation of the invention in specific forms of implementation for option No. 2 of the present invention is a scintillator material in the form of a single crystal which has a composition CexLu2,076-xLamYnSi0,962O5,038where x is from 1× 10-4F. ed. to 0.02 F. ed., m - not more than 0,05 F. ed., n - 1× 10-4F. ed. to 2.0 F. ed.

The growing Czochralski crystal orthosilicate lutetium-yttrium-lanthanum-cerium with the chemical composition Ce0,002Lu1,324Y0,7La0,05Si0,962O5,038was obtained from the iridium crucible with an inner diameter of 36 mm and a height of 38 mm with a speed of extrusion of 3 mm/h and the frequency of rotation of 15 rpm, the crystallization was carried out from a melt made from the charge composition, characterized by the molar zootoxin the argon atmosphere (of 99.5 volume% Ar+0.5% of the volume O2). Crystal with a diameter of 16 mm and a length of cylindrical portion 60 mm was colorless and had no cracks during its cultivation, however, in the period of 24 hours cooling in the middle part of the crystal cracked. The upper part of the crystal did not contain light scattering centers, but in the lower part of the bulls was attended by numerous centers of light scattering. Sample from the upper part of the crystal was demonstrated when gamma excitation light output 1.3 times higher than the "reference" sample Ce0,0024Lu1,998SiO5the method of manufacture described in example No. 1.

Example 6. Scintillation substance containing lithium options # 3 and # 4 of this invention has a composition expressed by a chemical formula CexLiq+pLu2-p+2y-x-zAzSi1-yO5+y-Rwhere x is from 1× 10-4F. ed. to 0.02 F. ed., y - from 0,024 F. ed. up to 0,09 F. ed., q - 1× 10-4F. ed. to 0.2 F. ed., R - 1× 10-4F. ed. 0.05 F. ed., z is not more than 0.05 F. ed.

To obtain single crystal Ce0,003Li0,005Lu2,049La0,02Si0,962O5,038used the following method of obtaining samples: source reagents lutetium oxide, silicon oxide and lithium carbonate composition, characterized molar cooleremail, extruded into pellets and synthesized in a platinum crucible in air for 10 hours at 1250° C. Then, by the induction heating, the tablets melted in the iridium crucible in a sealed chamber in a protective atmosphere (99.7% of the volume of N2+0,3% volume O2). Before growing into the melt was added to the cerium oxide. Crystal with a diameter of 60 mm and a length of the cylindrical part 45 were grown by the kyropoulos method of iridium crucible with an inner diameter of 76 mm and a height of 78 mm, the Volume of the initial melt was equal to 290 cm3. The rate of crystal growth at different stages varied from 1 to 8 mm/h at the frequency of rotation of the crystal about 10/min After separation of the grown crystal from the remnants of the melt, the crystal was slowly cooled to room temperature for 30 hours. Polished samples from the crystal used for measurement of parameters, which are presented in Table 1.

The growing Czochralski scintillation substance based on a silicate lutetium and cerium containing lithium chemical composition CexLi0,08Lu2,026-xSi0,962O5,008-p, was obtained from the iridium crucible with an inner diameter of 36 mm and a height of 38 mm with a speed of extrusion of 2.7 mm/h and the frequency of rotation 14 Rev/min. Procatechesis of oxides 51.9% of (Lu2O3+La2O3+Ce2O3)/48.1% in SiO2in a protective argon atmosphere (99,7% by volume Ar+0.3% of the volume O2). Crystal with a diameter of 19 mm and a length of cylindrical portion 60 mm was colorless and had no cracks during its production and during the period of 22 time cooling. Both the upper and the lower part of the crystal did not contain centers of light scattering within the volume boules, except for the peripheral region thickness of about 0,5-0,7 mm Sample, the method of manufacture described in example No. 1, cut from the upper part of the crystal, demonstrated when gamma excitation light output approximately equal to the "reference" sample Lu1,998Ce0,0024SiO5. On the same technological scheme grew and cut crystal compositions CexLi0,02Lu2,072-xSi0,962O5,034CexLu2,036-xY0,04Si0,962O5,038CexLiof 0.2Lu2,006-xGd0,04Si0,962O5,018CexLiof 0.15Lu2,071-x-zTbzSi0,962O4,988with different content of cerium x - 1× 10-4F. ed. to 0.02 F. ed.

Example 7. Scintillation substance according to variant No. 5 on the basis of silicate lutetium-cerium-containing cation vacancies and having a composition, which virajaet x - 1× 10-4F. ed. to 0.1 F. ed.

The growing Czochralski scintillation substance based on monocationic silicate lutetium-cerium, having a chemical composition Ce0,002Lu9,3280,67Si6O26, was obtained from the iridium crucible with an inner diameter of 37 mm and a height of 40 mm, with the rate of extrusion was 2.7 mm/h and a speed of 14 rpm crystallization was carried out from a melt made from the charge of stoichiometric composition, in a protective argon atmosphere (99,7% by volume Ar+0.3% of the volume Of2). Crystal with a diameter of 22 mm and a length of the cylindrical part 58 mm was colorless and had no cracks during its production and during 12 hour cooling. On the whole volume of the crystal there was a small scattering, the density of which is increased in the lower part of the crystal. Scintillation samples were produced according to the method described in example No. 1.

On the same technological scheme grew and cut crystal compositions Ce0,04Lu9,290,67Si6O26Cea 0.1Lu9,230,67Si6O26. It should be noted that p is emer 8. Scintillation substance according to variant No. 6 on the basis of silicate lutetium-cerium containing lithium and cation vacancies, having a composition expressed by a chemical formula CexLiq+pLuwas 9.33-x-p0,67Si6O26-pwhere x is from 1× 10-4F. ed. to 0.1 F. ed., q - 1× 10-4F. ed. to 0.3 F. ed., R - 1× 10-4F. ed. to 0.25 F. ed.

The growing Czochralski scintillation substance based on monocationic silicate lutetium and cerium containing lithium chemical composition Ce0,002Liof 0.2Lu9,1280,67Si6O25,8, was obtained from the iridium crucible with an inner diameter of 37 mm and a height of 40 mm, with the rate of extrusion of 2.7 mm/h and a speed of 12 rpm crystallization was carried out from a melt made from the charge of stoichiometric composition, in a protective nitrogen atmosphere (to 99.9 %by volume of N2+0,1 vol % O2). Crystal with a diameter of 22 mm and a length of the cylindrical part 52 mm was colorless and had no cracks during its production and during 12 hour cooling. In the crystal there was a small scattering. Scintillation samples were produced according to the method the op is 0,001Li0,12Lu9,2790,67Si6O25,95. CE0,05Lifor 0.4Luthe remaining 9.080,67Si6O25,8.

Example 9. Scintillation substance according to variant No. 7 on the basis of silicate lutetium-cerium containing lithium and cation vacancies and having a composition expressed by a chemical formula CexLiq+pLuwas 9.33-x-p-z0,67AzSi6O26-pwhere a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb, x - 1× 10-4F. ed. to 0.1 F. ed.; q - 1× 10-4F. ed. to 0.3 F. ed., R - 1× 10-4F. ed. to 0.25 F. ed., z - 5× 10-4F. ed. to 8.9 F. ed.

The growing Czochralski scintillation substance based on monocationic silicate lutetium and cerium containing lithium chemical composition Ce0,002Liof 0.2Lu7,228-p0,67La2Si6O25,9, was obtained from the iridium crucible with an inner diameter of 37 mm and a height of 40 mm, with the rate of extrusion was 2.7 mm/h and a speed of 12 rpm crystallization was carried out from a melt made from the charge of stoichiometric composition, protection is some part 52 mm was colorless and had no cracks during its production and during 12 hour cooling. In the crystal there was a small scattering. Scintillation samples were produced according to the method described in example No. 1.

On the same technological scheme grew and cut crystal compositions Ce0,002Liof 0.2Lu1,228-p0,67Y8Si6O25,9Ce0,001Lia 0.1Lu8,3240,67YSi6O25,995Ce0,001Liof 0.15Lu4,2790,67Gd5Si6O25,95Ce0,001Li0,35Lu9,1090,67Tbof 0.2Si6O25,8Ce0,002Lia 0.1Lu0,4230,67La8,9Si6O25,95.

Example 10. Scintillation substance according to options # 8 and # 9 on the basis of silicate lutetium-cerium containing lithium Li in a quantity of at least one formula unit and having a composition expressed by a chemical formula CexLi1+q+pLu9-x-pSi6O26-pwhere x is from 1× 10-4F. ed. to 0.1 F. ed.; q in the amount of not less than 0.3 F. ed., p in an amount not less than 0.25 F. ed.

Important technical hallmark data scintillation substances I have intellitrace in the structural type oxyorthosilicate lutetium. Such low melting point is an important advantage for growing crystals by the Czochralski method, as in this case, the lifetime of iridium crucibles increases tenfold. Even more important long life iridium products, if the process of crystal growth is carried out by the Stepanov method. The application of the Stepanov method opens up the possibility of growing several tens of scintillation crystals, such as size 2× 2× 100 mm-or size 1× 1× 50 mm, In this case not expensive operation sawing large boules into thin rods. With this cutting waste can take up to 20-50% of single-crystal substance, which dramatically increases the cost of scintillation elements for medical micropositioner tomography (MicroPET).

In the growth process shaped crystal from the melt its cross-section is determined by the form of a melt column. To shape the melt using different physical effects. The creation of a melt column of rectangular cross-section, typically performed using iridium shaper. The design of the formers and the method of calculating the optimal provenancial and products by the Stepanov method", Leningrad, "Nauka", 1981, 280 S.

Growing profiled crystal Stepanov method was carried out using the iridium iridium crucible with a shaper, having a cross-section of the outer edge 2× 2 mm, which asked a cross-section of the growing crystal. To obtain crystal Ce0,045Li1,300Lu8,905Si6O25,995, crystallizing in the hexagonal crystal system, used a mixture of stoichiometric composition, chemical formula in which formula units has the form Ce0,045Li1,300Lu8,905Si6O25,995. For batch used the following method. The source reagents carbonate of lithium, lutetium oxide and silicon oxide are thoroughly mixed and partially synthesized powder in a platinum crucible in air for 10 h at 1300° C. Then, by the induction heating, the powder was melted in an iridium crucible in flowing protective atmosphere (99.7% of the volume of N2+0,3% volume O2). Before growing into the melt was added to the cerium oxide. The shaper was allowed to grow from one to nine shaped crystals at the same time. Seeding was performed on the crystal obtained by the Czochralski method. The seed crystal was cut in crystallographic APM/h without rotation. After the crystals length of 50 mm were detached from the shaper sharp increase in the rate of stretching and 30 minutes later was removed from the installation.

Shaped crystalline rods were cut into several scintillation elements size 2× 2× 10. Polished samples of crystal Ce0,045Li1,300Lu8,905Si6O25,995were used to measure parameters, which are presented in Table 1.

On the same technological scheme grew and cut crystal compositions Ce0,001LiLu8,998Si6O26Ce0,04LiLu8,96Si6O26Cea 0.1LiLu8,9Si6O26Ce0,002Li1,45Lu8,798-pSi6O25,8Ce0,0015Li1,3Lu8,8985-pSi6O25,9.

Example 11. Scintillation substance according to variant No. 10 on the basis of silicate lutetium-cerium containing lithium Li in a quantity of more than one formula unit and having a composition expressed by a chemical formula CexLi1+q+pLu9-x-p-zAzSi6O26-pwhere a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb; x 1× 10-4F. ed. to 0.1 F. ed.; q - 1× 10-4F. ed. to 0.3 F. ed.; R - 1× 10-4F. ed. to 0.25 F. ed.; z - 5Ò,02Y8,755Si6O26, crystallizing in the hexagonal crystal system, used a mixture of stoichiometric composition, chemical formula in the formula units has the form Ce0,045Li1,1Lu0,08La0,02Y8,755Si6O26. The growing crystal was obtained from the iridium crucible with a diameter of 40 mm in a protective atmosphere (99.5% of the volume of N2+0.5% of the volume O2), a growth rate of 5 mm/h 10 mm/h and the frequency of rotation 11/min under these conditions was grown on the crystal length of 35 mm and a diameter of 18 mm, which was light yellow in color and does not contain light scattering centers even when the growth rate of 10 mm/h Polished sample from this crystal showed under gamma excitation light output is about 10 times lower than the "reference" sample Lu1,998Ce0,0024SiO5the method of manufacture described in example 1. Based on this, for substances variant No. 10 with the General formula CexLi1+q+pLu9-x-p-zAzSi6O26-pwas determined the upper limit of substitution (z=8.9 F. ed.) ions lutetium to other elements. The upper limit is set to 8.9 F. ed., in this case, the crystals have a much lower density and light output with a sharp reduction are what I use in sensors, where the most important parameter is the low cost and high stability of the scintillation crystal to the external factors that lead down dosimetric device (high temperature, high humidity, high radiation levels).

On the same technological scheme grew crystals of compositions Ce0,001Li1,2Lu3,898Gd5,1Si6O26Ce0,04Li1,2Lu8,66Euof 0.2Si6O25,9Cea 0.1Li1,2Lu7,9Sc0,8Si6O25,8Ce0,002Li1,45Lu6,298Ythe 2.5Si6O25,8Ce0,0015Li1,3Lu8,3985La0,5Si6O25,9.

Table 1 shows the test results of the synthesized scintillation substances on the effect of the afterglow, the amount of light output, decay time, density, Zeff.

Claims

1. Scintillation substance based on a silicate containing lutetium Lu and cerium CE, characterized in that the composition of a substance expressed by a chemical formula

CexLu2+2y-xSi1-yAbout5+y,

where x is from 1·10-4F. ed. to 0.02 F. ed.;

y - from 0,024 F. ed. up to 0,09 F. ed.

2. Scintillation of wishes>Lu2,076-xSi0,962O5,038,

where x is from 1·10-4F. ed. to 0.02 F. ed.

3. A method of obtaining a scintillation substance based on a silicate, as described in paragraph 1, wherein the grown single crystal directional solidification from a melt made from the charge composition, characterized by the molar ratio of oxides 51.9% of(Lu2O3+CE2O3):48,1%SiO2.

4. A method of obtaining a scintillation substance based on a silicate, as described in paragraph 1, by the Czochralski method, characterized in that the grown single crystal from a melt made from the charge composition, characterized by the molar ratio of oxides 51.9% of(Lu2O3+CE2O3):48,1%SiO2.

5. Scintillation substance based on a silicate containing lutetium Lu and cerium CE, characterized in that the composition of a substance in the form of a single crystal expressed by the chemical formula

CexLu2+2y-x-zAzSi1-yO5+y,

where a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb, Ca;

x - 1·10-4F. ed. to 0.02 F. ed.;

y - from 0,024 F. ed. up to 0,09 F. ed.;

z - 1·10-4F. ed. 0.05 F. ed.

6. Scintillation substance according to p. 5, characterized in that the composition of wishes>the de And at least one of the elements of the group Gd, Sc, Y, La, Eu, Tb, Ca;

x - 1·10-4F. ed. to 0.02 F. ed.;

z - 1·10-4F. ed. 0.05 F. ed.

7. Scintillation substance according to p. 5, characterized in that the composition of a substance in the form of a single crystal expressed by the chemical formula

CexLu2,076-x-m-nLamYnSi0,962O5,038,

where x is from 1·10-4F. ed. to 0.02 F. ed.;

m - not more than 0,05 F. ed.;

n - 1·10-4F. ed. to 2.0 F. ed.

8. A method of obtaining a scintillation substance based on a crystal silicate, as described in paragraph 5, wherein the growing of the single crystal directional solidification is produced from a melt made from the charge composition, characterized by the molar ratio of oxides 51.9% of (Lu2O3+A2O3+CE2O3):48,1%SiO2where a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb.

9. A method of obtaining a scintillation substance based on a crystal silicate, as described in paragraph 5, characterized in that the cultivation of ultra-large single crystals by the method of Kyropoulos is produced from a melt made from the charge composition, characterized by the molar ratio of oxides 51.9% of(Lu2O3+A>0. Scintillation substance based on a silicate containing lutetium Lu and cerium CE, characterized in that it contains lithium Li in a quantity not exceeding 0.25 F. ed., and the composition is expressed by a chemical formula

CExLiq+pLu2-p+2y-xSi1-yO5+y-p

where x is from 1·10-4F. ed. to 0.02 F. ed.;

y - from 0,024 F. ed. up to 0,09 F. ed.;

q - 1·10-4F. ed. to 0.2 F. ed.;

R - 1·10-4F. ed. 0.05 F. ed.

11. Scintillation substance according to p. 10, characterized in that the composition of a substance in the form of a single crystal containing lithium in an amount not exceeding 0.25 F. ed., is expressed by a chemical formula

CExLiq+pLu2,076-p-xSi0,962O5,038-p,

where x is from 1·10-4F. ed. to 0.02 F. ed.;

q - 1·10-4F. ed. to 0.2 F. ed.;

R - 1·10-4F. ed. 0.05 F. ed.

12. A method of obtaining a scintillation substance based on a silicate, as described in paragraph 10, wherein the grown single crystal directional solidification from a melt made from the charge composition, characterized by the molar ratio of oxides 51.9% of (Lu2O3+Li2O+Ce2O3):48,1% SiO2.

13. Scintillation substance based on a silicate containing lutetium Lu and cerium With the coy formula

CExLiq+pLu2-p+2y-x-zAzSi1-yO5+y-p,

where a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb;

x - 1·10-4F. ed. to 0.02 F. ed.;

y - from 0,024 F. ed. up to 0,09 F. ed.;

z - 1·10-4F. ed. 0.05 F. ed.;

q - 1·10-4F. ed. to 0.02 F. ed.;

R - 1·10-4F. ed. 0.05 F. ed.

14. Scintillation substance according to p. 13, characterized in that the composition of a substance in the form of a single crystal containing lithium Li in a quantity not exceeding 0.25 F. ed., is expressed by a chemical formula

CExLiq+pLu2,076-p-x-zAzSi0,962O5,038-p,

where a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb;

x - 1·10-4F. ed. to 0.02 F. ed.;

z - 1·10-4F. ed. 0.05 F. ed.;

q - 1·10-4F. ed. to 0.2 F. ed.;

R - 1·10-4F. ed. 0.05 F. ed.

15. A method of obtaining a scintillation substance based on a silicate, as described in paragraph 13, wherein the grown single crystal directional solidification from a melt made from the charge composition, characterized by the molar ratio of oxides 51.9% of (Lu2O3+Li2O+A2O3+CE2O3):48,1% SiO2.

16. Scintillation substance based on silikatnogo

CExLuwas 9.33-x0,67Si6O26,

where x is from 1·10-4F. ed. to 0.1 F. ed.

17. Scintillation substance based on a silicate containing lutetium Lu and cerium CE, characterized in that it contains a Li Li and has a composition that is expressed by a chemical formula

CExLiq+pLuwas 9.33-x-p0,67Si6O26-p,

where x is from 1·10-4F. ed. to 0.1 F. ed.;

q - 1·10-4F. ed. to 0.3 F. ed.;

R - 1·10-4F. ed. to 0.25 F. ed.

18. Scintillation substance based on a silicate containing lutetium Lu and cerium CE, characterized in that it contains a Li Li and has a composition that is expressed by a chemical formula

CExLiq+pLuwas 9.33-x-p-z0,67AzSi6O26-p,

where a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb;

x - 1·10-4F. ed. to 0.1 F. ed.;

q - 1·10-4F. ed. to 0.3 F. ed.;

R - 1·10-4F. ed. to 0.25 F. ed.;

z - 5·10-4F. ed. to 8.9 F. ed.

19. Scintillation substance based on a silicate containing lutetium Lu and cerium CE, characterized in that it contains a Li Li and composition of substances in,1 f.ed.

20. Scintillation substance based on a silicate containing lutetium Lu and cerium CE, characterized in that it contains lithium Li in a quantity of more than one formula unit and the composition of a substance expressed by a chemical formula

CExLi1+q+pLu9-x-pSi6About26-p,

where x is from 1·10-4F. ed. to 0.1 F. ed.;

q - 1·10-4F. ed. to 0.3 F. ed.;

R - 1·10-4F. ed. to 0.25 F. ed.

21. Scintillation substance based on a silicate containing lutetium Lu and cerium CE, characterized in that it contains lithium Li in a quantity of more than one formula unit and the composition of a substance expressed by a chemical formula

CExLi1+q+pLu9-x-p-zAzSi6O26-p,

where a is at least one element from the group of Gd, Sc, Y, La, Eu, Tb;

x - 1·10-4F. ed. to 0.1 F. ed.;

q - 1·10-4F. ed. to 0.3 F. ed.;

R - 1·10-4F. ed. to 0.25 F. ed.;

z - 5·10-4F. ed. to 8.9 F. ed.



 

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