A method of obtaining a charge for growing single crystals of galloylated with the structure of calcium gallogermanate

 

(57) Abstract:

The invention relates to chemical technology, namely the technology of preparation furnace for growing a new class of ordered four compounds galloylated with the structure of gallogermanate calcium (Ca3Ga2Ge4O14). The essence of the invention: method of solid-phase synthesis of conducting the pre-mixing through heat treatment of the oxides of the elements included in the composition of the grown single crystal Ca3MeGa3Si2O14where IU is niobium or tantalum, taken in stoichiometric ratio, heating and sintering the mixture at a temperature component of 92-94% of the temperature of synthesis of the corresponding single crystals within 4 hours Technical result is to create a cost-effective method of obtaining a mixture in a compact rational (in the form of a shaped tablets) for growing high-quality single crystals of galloylated used used in piezoelectric engineering. table 1.

The invention relates to chemical technology, namely the technology of preparation furnace for growing a new class of ordered four connections Gallois get charge for growing single crystals of compounds with the structure of langasite by heating a mixture of carbonates of alkaline earth metals and oxides of the elements, members of the as-grown crystals are taken in stoichiometric ratio (C. N. T. Chai, A. N. P. Bustamante and M. C. Chou// A new class of ordered langasite structure compounds// 2000 IEEE/EIA International Frequency Control Symposium and Exhibition, p. 163-167).

However, the use as a component of sintered mixture of carbonate of alkaline earth metal included in the composition of the grown crystal, requires a longer heating process for its decomposition, which in turn increases the time that the process violates the stoichiometric composition of the mixture and, consequently, reduces the yield of the final gallosilikata.

The closest in technical essence and the achieved result is a method of obtaining a charge for growing single crystals of galloylated with the structure of gallogermanate calcium (Ca3Ga2Ge4O14using the method of solid-phase synthesis by roasting in air mixture of the initial components: carbonates, alkaline earth component and oxides of the elements included in the composition of the grown single crystal at a temperature of synthesis of the corresponding single crystal for 5-12 h (B. C. mill, E. L. Belokoneva, T. Fukuda// New connection with the structure of CA3GA2GE4O14: A3HU3< a CLASS="ptx2">

The disadvantage of this method is the use as a component in the sintered mixture of carbonate of alkaline earth metal, which requires long annealing for its decomposition, which increases the time of sintering the mixture, and consequently, makes the method of preparation of the charge is economically disadvantageous. Increasing time of annealing leads to loss of the volatile component, which is reflected at the output end of the grown crystal, reducing its quality. Sintering the mixture at a temperature of synthesis leads to the melting of the charge and the interaction of the melt with the crucible walls that pollutes the charge, and in turn grow the crystal, and also leads to the destruction of the crucibles and the impossibility of obtaining the mixture in a rational tablet form.

The technical object of the present invention is to provide an economically advantageous method of producing the mixture in a compact rational (in the form of a shaped tablets) for growing high-quality single crystals of galloylated used used in piezoelectric engineering.

The mentioned technical problem is solved due to the fact that in the known method of solid-phase synthesis mixture, comprising mixing recognize the m ratio, heating and sintering, the grown single crystal has a composition of Ca3MeGa3Si2O14where IU is tantalum or niobium, as a source of a mixture of compounds of elements using the corresponding oxides previously undergone heat treatment and sintering of the mixture is carried out at a temperature of 92-94% of the temperature of synthesis of the corresponding single crystals within 4 hours

Comparative analysis of the proposed solutions with the prototype shows that the inventive method differs from the known source connections use only the oxides of the elements included in the composition of galloylated CA3Honey3Si2O14where Me is tantalum or niobium, which before mixing subjected to heat treatment and sintering of the mixture is carried out at a temperature of 92-94% of the temperature of synthesis of the corresponding single crystals within 4 hours

Use in the way that only oxides avoids violation of the stoichiometry of the melt during subsequent single crystal growth by reducing the duration of the annealing mixture, which reduces the effect of the loss of the volatile component, and therefore, to obtain high-quality monocrat is a, and therefore, causes the exception of cultivation substandard crystals. Sintering the mixture at a temperature of 92-94% of the temperature of synthesis of the corresponding single crystals, can prevent the melting of the charge, and therefore, its interaction with the walls of the crucible. Sintering the mixture at a temperature below that allows you to get a charge in a compact form and at a higher temperature, it is sticking to the walls of the crucible. Sintering the mixture for 4 h is sufficient to obtain a shaped tablets mixture of calcium-niobium-gallium silicate - Ca3NbGa3Si2ABOUT14-CNGS (changeset) and calcium-tantalum-gallium silicate - Ca3TaGa3Si2O14- CTGS (katamatite), which allow for growing the respective single crystals to build-up of charge at one time and get a higher quality crystals at the expense of smaller violations of the stoichiometric composition of the mixture. Sintering the mixture at least 4 hours is not possible to obtain a pelletized mixture, resulting in high quality and exposure for more than 4 h uneconomic.

Examples of specific performance.

Example 1.

The original oxides ka is Oseni and 215 g of the mixture are mixed in a polyethylene jar with mixer type "drunken barrel", download in alongby the crucible, namely in the space between its inner wall and lundevall tube installed in the Central part of the crucible. The diameter Lungolago crucible was 60 mm diameter iridium crucible from which to further grow the single crystal. The crucible is set in the oven and spend sintering the mixture at a temperature of 92-94% of the temperature of synthesis of Ca3NbGa3Si2ABOUT14within 4 hours At the sintering get profiled tablet charge for growing single crystals of calcium - niobium - gallium silicate (Ca3NbGa3Si2O14- changeset) with a hole along its axis. From the synthesized charge grow single crystals of the calcium-niobium-gallium silicate with a diameter of 1.5 inches. The results of the method at different sintering parameters presented in the table. Sintering of the three sub-samples of the original mixture of oxides, weight 215 grams each, allows you to get three profiled pill burden, total weight of which will give the opportunity to immediately apply the full amount of the iridium crucible, which will continue to grow the single crystal.

Example 2.

Same as in example 1, but starting components take OKS the temperature of synthesis of Ca3TaGa3Si2ABOUT14. As a result identical way to get quality polycrystalline mixture in tablet form for growing single crystals of calcium-tantalum-gallium silicate (CA3Tada3Si2ABOUT14- CTGS - katamatite) with a diameter of 1.5 inches.

The proposed method of producing the mixture for growing galloylated with the structure of gallogermanate calcium (CA3GA2GE4O14), namely changeset and katamatite allows

- to reduce the number of preliminary operations;

- get profiled tablets qualitative mixture of the required mass and size to fill the entire volume of iridium crucible when growing a single crystal;

to avoid breaking the stoichiometry of the melt, as synthesized tablets fully used when fusing them into a crucible, and therefore, to obtain homogeneous single crystals for use used in piezoelectric engineering.

A method of obtaining a charge for growing single crystals of galloylated with the structure of gallogermanate calcium by the method of solid-phase synthesis, including the mixing of compounds of the elements included in the form is aemy the single crystal has a composition of Ca3MeGa3Si2O14where IU is tantalum or niobium, as a source of a mixture of compounds using the appropriate oxides previously undergone heat treatment and sintering of the mixture is carried out at a temperature of 92-94% of the temperature of synthesis of the corresponding single crystals within 4 hours

 

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FIELD: chemical industry; methods of production of mullite out of the quartz-topaz raw materials.

SUBSTANCE: the invention is pertaining to the field of a chemical industry, chemical technology and materials technology. The method of production of mullite includes: comminution of the source quartz-topaz raw materials; separation of impurities by lixiviation using treatment of the raw materials with a hydrochloric acid with concentration of 10-38 % within 0.5-2 hours; a water flushing; separation of redundant silicon oxide in the form of ammonium hexafluorosilicate by means of ammonium bifluoride; calcination of the gained product at the temperature of 1200°-1300°C. The technical result of the invention is production of the microfibrous mullite (microfibers of the mullite crystal may reach 200 microns in length with a fiber depth - about 1 micron) of high quality and in the commercial scale.

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1 ex

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EFFECT: enhanced efficiency.

1 ex

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SUBSTANCE: the invention is pertaining to the method of production of the crystals with the triclinic crystal system. Substance of the invention: the monocrystals of lanthanum-gallium silicate grown in compliance with Czochralski method from the iridium crusible are subjected to the two-stage thermal treatment. The monocrystals are preliminary subjected to the vacuum annealing at the pressure of 1·10-2 -1·10-4Pa and the temperature of 600-1200°C within 0.5-10 hours, and then conduct their isothermal air aging at the temperature of 300-350°C within 0.5-48 hours. The invention allows reproducibly produce the discolored monocrystals of lanthanum-gallium silicate and also to speed up propagation of the surface-acoustic waves (SAW) by 1-1.5 m\s at the simultaneous decrease of dispersion of the waves propagation velocity by 20-30 ppm.

EFFECT: the invention ensures production of the discolored monocrystals of lanthanum-gallium silicate and allows to increase the speed of propagation of the surface-acoustic waves at simultaneous reduction of the waves propagation dispersion by 20-30 ppm.

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3 cl, 3 tbl, 3 ex

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EFFECT: the invention ensures the improved frequency characteristics of the devices operating in the surface acoustic waves range, provision of production of the plain parallel substrates at the speed of removal of the substrate material within the range of 5-10 microns/hour at achievement of the roughness of the lapped surface below 1 nanometer.

5 cl, 1 ex

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1 ex

FIELD: scintillation materials.

SUBSTANCE: invention relates to novel crystalline scintillators that can be used to detect ionizing emissions for medical diagnostics, nuclear geophysics, and for non-damaging checking of nutrition product quality. Silicate-based scintillation substance contains lutetium, cerium, and germanium, its composition being defined by following chemical formula: Ce2xLu2(1-x)Si1-yGeyO5, where x = 1·10-4-0.03 and y = 1·10-4-0.20. Scintillation substance can be supplemented by yttrium and, in this case, its composition will be defined by following formula: Ce2xLu2(1-x-z)Y2xSi1-yGeyO5, where x = 1·10-4-0.03, y = 1·10-3-0.20, and z = 1·10-3-0.5. Novel scintillation substances exhibit improved consumer's properties (high density, high light output, short scintillation deexcitation time), which extends application area thereof and, in particular, allows use in detection devices for registration and spectrometry of particles and quanta having high, median, and low energies. When in use in medical diagnostics, elevated high light output will increase sensitivity of registration system and contrast of image, whereas high density and, thereby, high absorption capacity for ionization emission will allow special resolution to be improved, and shorter scintillation deexcitation time will reduce radiation exposure for a patient.

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