Hydrothermal process for growing large crystals of aluminum orthophosphate or gallium

 

(57) Abstract:

The invention relates to the technology of growing metallitoostus, in particular AlPO4and GaPO4that can be used used in piezoelectric engineering, namely in resonators and filters for various purposes. The invention allows to obtain large crystals orthophosphate metals, are free from defects. The inventive method includes the epitaxy on the quartz seed basic orientation of saturated ions of the metal phosphate solution in the presence of additives Li+in the amount of 0.05 to 10.0 weight. % with increasing temperature and constant temperature differential, the manufacturer of the resulting layer of the bare plate and recrystallization on it corresponding to the obtained crystal mixture of sulfuric acid, phosphoric acid or their mixture solutions at constant temperature differential. table 1.

The invention relates to the technology of growing metallitoostus, in particular AlPO4and GaPO4- the structural analogs of the well-known piezoelectric material L-quartz, with greater than quartz, piezoelectric constants and high thermal stability of the resonant frequencies of the piezoelectric elements to

A method of obtaining large crystals orthophosphate metals using a seed crystal plates (U.S. Pat. USA 5377615, MKI: 30 In 29/14, priority from 22.05.92,), in which large crystals AlPO4and GaPO4receive by increasing the size of the seed to the desired by fastening small seeds on the substrate and growing already on them from the nutrient solution single crystals. The disadvantage of this method is the complexity of the synthesis process due to the need for high precision orientation, the ends of which are connected with the seed plate, the possibility of synthetically produced crystals AlPO4and GaPO4.

The closest technical solution of the present invention is a hydrothermal process for growing large crystals or crystalline layers metallitoostus, in particular AlPO4and GaPO4(U.S. Pat. USA 5375556, MKI C 30 B 7/10, priority 23.08.93), in which large crystals obtained by deposition of a layer of initial orthophosphate metal on a quartz plate basic orientation of nutrients (2-15)M phosphate solution saturated with ions of the metal with the addition of fluoride ions, stimulating restofline from this layer of the bare plate and build on it by recrystallization of the mixture from nutrient solutions (H3PO4H2SO4) crystals for practical purposes. However, this method does not provide basefactory grown layer on the quartz seed from which are produced the bare plate to build on them large size crystals. And hence the decline in the quality of the obtained single crystals for practical purposes.

The technical object of the present invention is to obtain large crystals orthophosphate metals aluminum or gallium, free from defects, with the aim of obtaining valuable raw material for use as a working element used in piezoelectric engineering.

The technical problem is solved due to the fact that in the hydrothermal method of growing large crystals orthophosphate metals aluminum or gallium, including epitaxy on a quartz seed basic orientation of saturated ions of the metal phosphate solution in the presence of additives, with increasing synthesis temperature and constant temperature differential, the manufacturer of the resulting layer of metal orthophosphate bare plate and recrystallization at her mixture of sulfuric acid, phosphoric acid or mixtures of rest the second acid is injected ions Li+in the amount of 0.05-10.0 wt.%.

Introduction in the first phase - epitaxy on a quartz seed crystal in a solution of phosphoric acid ions Li+facilitates the formation of the first crystal layer metallitoostus (AlPO4and GaPO4) on the quartz seed. Ions Li+with excess positive charge with a small ionic radius, with the introduction of the solution form strong links with the negatively charged grid data crystals, which reduces the probability of separation of impurity adsorption and leads to building on the vacant seats of its own particles of the crystal. Required quantity introduced into the solution ions Li+selected in the range of 0.05 to 10.0 weight. % empirically. When the concentration of ions Li+achieved high rates of growth faces (0001) and the homogeneity of the obtained material. When epitaxy orthophosphate aluminum or gallium on quartz from a solution of orthophosphoric acid with the concentration of ions Li+less than 0.05 wt.% or more than 10.0 weight. % observed many-headed growth, the face of pinacoid becomes morphologically unstable and impossible to get a quality grown layer orthophoto metals aluminum or gallium, which are required RA is lia.

Examples of specific performance

Example 1. Vertical autoclave, separated by a perforated partition into two parts, with a capacity of 1 l pour pre-cooked 8.7 M solution of H3PO4saturated ions Al3+. The fill factor of the autoclave is 0.9. In the specified nutrient solution H3PO4introducing additive ions Li+in the form of soluble compounds Li(OH). The concentration of the ions Li+in a solution of 0.05 to 10.0 weight. %. In the lower part of the autoclave is placed a quartz seed basic orientation. The autoclave is sealed and placed in an oven, conduct the process of epitaxy on a quartz seed crystal at a slow rise of temperature from 155 to 240oWith the camera dissolution and constant temperature differential of 10oC. After that, the autoclave opened. Quartz seeds get high-quality defect-free layer of aluminum orthophosphate, which is then used as the seed. Conduct the second stage. The autoclave pour 6M solution of H2SO4. The fill factor of 0.9. In the upper part of the autoclave is placed the charge AlPO4and the lower seed, cut from single-crystal layers AlPO4. The autoclave is sealed, placed in an oven for heating, conduct process paraceratherium quality single crystals berlinite AlPO4used as raw material for piezotechnique.

Example 2. Same as in example 1, but the second stage is the growing of single crystals on a previously received the seed plate by recrystallization of the charge - lead from 8.7 M solution of H3PO4when the crystallization temperature 175oWith a temperature differential of 10oC. Get large high-quality single crystal berlinite AlPO4.

Example 3. Same as in example 1, but as hydrothermal solution in the second step for growing single crystals of a mixture of solutions of H3PO4and H2SO4in the ratio of 1:7, and the mixture solutions take the concentration of 6M. Receive high-quality large-size single crystal berlinite AlPO4for piezotechnique.

Example 4. Same as in example 1, but epitaxy on quartz conduct of nutrient 12M solution of H3RHO4saturated with gallium ions, with the addition of ions Li+. The result of grown layer GaPO, from which cut seed GaPO4used for synthesis of single crystals by recrystallization of the mixture under hydrothermal conditions. Receive high-quality large-size single crystal Daro4for fosforos acid during epitaxy ion Li+summarized in a table.

The use of this method for the synthesis of orthophosphate metals of aluminum and gallium allows one to obtain large crystals, free from defects, properties which make orthophosphate valuable minerals for use as a working element in devices based on saw and BAW, such as resonators, delay lines, filters, and other

Hydrothermal process for growing large crystals of orthophosphate aluminum or gallium, including epitaxy on a quartz seed basic orientation of saturated ions of the metal phosphate solution in the presence of additives with increasing synthesis temperature and constant temperature differential, the manufacturer of the resulting layer of the bare plate and recrystallization on it corresponding to the obtained crystal mixture of sulfuric acid, phosphoric acid or their mixture solutions at constant temperature differential, characterized in that as an additive in epitaxy on the quartz seed crystal in a solution of phosphoric acid is injected ions Li+in the amount of 0.05-10.0 wt.%.

 

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FIELD: production if monocrystals.

SUBSTANCE: production of tetragonal monocrystal at composition of Z(H,D)2MO4, where Z is element of group of elements or mixture of elements and/or group of elements selected from group, K,N (H,D)4, Rb, Ce, where M is element selected from group P, As and (H,D) is hydrogen or deuterium which may be used for manufacture of optical components for lasers, for example. Proposed monocrystal contains practically parallelepiped zone of large size whose sizes AC1, AC2 and AC3 of each edge of faces exceed or are equal to 100 mm, exceed or are equal to 200 or 500 mm obtained by growing the crystal in solution from practically parallelepiped monocrystal seed whose edges have sizes AG1, AG2 and AG3. Size AG1 of at least one edge of seed exceeds or is equal to 1/10, preferably of size of edge of monocrystal face and other size of seed AG3 is lesser than or is equal to 1/5, preferably to 1/10 of maximum size of edges of seed.

EFFECT: possibility of production of blanks of large sizes; increased yield of plates in cutting.

26 cl, 5 dwg

FIELD: fast growing of crystals, type KH2PO4(KDP) at constant filtration of solution.

SUBSTANCE: proposed method includes crystallization for seed from supersaturated solution, removal of part of solution, superheating above saturation temperature, filtration and stabilization of solution temperature in crystallizer to crystallization temperature by means of filtering system. Stabilization of solution temperature is performed by periodic delivery of cleaned solution overheated above saturation temperature from filtering system at simultaneous discharge of the same amount of solution whose temperature is below crystallization temperature from crystallizer. Delivery of superheated solution is continued till moment when temperature of solution contained in crystallizer gets equal to crystallization temperature which is shown by temperature sensor. Provision is made for delivery of solution superheated above saturation temperature. Stabilization of temperature which is better than ±0.05°C is performed at periodic delivery of superheated solution. Proposed method makes it possible to make use of air cooling of foam plastic or porolon thermostats instead of liquid thermostat. Device proposed for realization of this method has bypass passage connected between inlet and outlet branch pipes in parallel with crystallizer. Filtered solution is circulating through this passage at periods when stabilization temperature is attained. Besides that, outlet end of bypass passage in brought out inside outlet branch pipe, thus excluding forming of parasites.

EFFECT: enhanced efficiency.

3 cl, 3 dwg

FIELD: physics.

SUBSTANCE: invention relates to the technology of growing crystals from salt solutions, particularly for growing KDP (KH2 PO4) group crystals which are widely used for making non-linear optical elements. The device has a crystallisation cup 1, a cover 2 of the crystallisation cup, a platform 4 with an inoculating crystal 5 and a mechanism for sealing the inoculating crystal. The cover 2 has an eccentric opening 10 which is tightly closed by a guide bushing 11, where the said opening is for letting in the mechanism for sealing the inoculating crystal 5, which is made in form of a cap 6 which is pressed to the surface of the platform 4 and hinged to an L-shaped bar 7, which can move coaxially with the guide bushing 11. Inside the bar 7 there is a channel 9 for connecting the cavity of the cap 6 to a pressure source. To connect the cavity of the cap 6 to the channel 9, there is a flexible bar 12 inside the L-shaped bar 7. The cap 6 is pressed to the platform 4 by a load or spring at the free end of the bar 7. The source of pressure applied inside the cap is atmospheric air.

EFFECT: crystals are widely used for making non-linear optical elements.

5 cl, 2 dwg

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