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Method for preparing lithium gallate crystals

A technology of lithium gallate and crystal, applied in the field of preparation of lithium gallate crystal, can solve the problems of serious melt volatilization, deviation of Li and Ga ratio from stoichiometric ratio, and high cost

Inactive Publication Date: 2012-10-03
SHANGHAI RES CENT OF ENG & TECH FOR SOLID STATE LIGHTING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The article published by Xu Ke in J.Cryst.Growth, 2000, 216(1-4): 343-347 disclosed that the transparent LiGaO of Φ15mm×60mm was grown by the pulling method 2 crystal, but the melt volatilizes seriously, and there is Ga in the crystal 2 o 3 Defects such as inclusions and subgrain boundaries
[0004] In the prior art, the main problem of preparing lithium gallate crystals is that in the process of crystal preparation, due to the high vapor pressure of the melt, severe gas convection is generated, resulting in LiO 2 The serious volatilization of Li and Ga in the melt deviates from the stoichiometric ratio, so defects visible to the naked eye such as bubbles and inclusions are prone to appear in the crystal
Moreover, it is easy to form crystal cores in places where Li is insufficient, especially when growing along the c-axis direction, it is also prone to crystal problems.
In addition, when using the pulling method to grow lithium gallate crystals, because the pulling method is to lift the crystal out of the liquid surface and then cool it down, it will cause a lot of stress in the crystal, and the cooling will be too fast to cause cracking problems.
[0005] Although some people consider that the growth of lithium gallate crystals by the Kyropoulos method can reduce the occurrence of defects and relieve the stress in the crystals, but the growth rate of the crystals by the Kyropoulos method is slow, it is difficult to take out the crystals after they grow out, and the cost is too high, so it is not suitable at present. Preparation of lithium gallate crystals

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  • Method for preparing lithium gallate crystals

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Experimental program
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Effect test

Embodiment approach

[0022] An embodiment of preparing lithium gallate crystals provided by the present invention includes:

[0023] Will Li 2 CO 3 and Ga 2 o 3 As raw materials mixed and compacted to obtain a molded body, the molded body is sintered;

[0024] Heating the molded body under vacuum conditions to obtain a melt, dipping the seed crystal into the cold core of the melt while rotating the seed crystal, shouldering and pulling at equal diameters, and cooling the melt to grow lithium gallate at the same time crystals.

[0025] According to the present invention, select Li 2 CO 3 and Ga 2 o 3 Powder is used as raw material, among which, Li 2 CO 3 The purity is preferably greater than 99.99wt%, and the powder particle size is preferably less than 120 μm, more preferably less than 180 μm, more preferably less than 50 μm; Ga 2 o 3 The purity is preferably greater than 99.99 wt%, and the particle size of the powder is preferably less than 120 μm, more preferably less than 180 μm, mo...

Embodiment 1

[0035] According to molar ratio Li 2 CO 3 : Ga 2 o 3 =1.05:1 Weigh Li with a purity of 99.999% 2 CO 3 Powder and Ga 2 o 3 Powder, the particle size of the two powders is 50 μm to 70 μm. After the two powders were mixed in a mixer for 48 hours, they were pressed into a molded body with a diameter of 80 mm, and the pressing pressure was 1 GPa. The molded body was placed in a crucible, and sintered in a muffle furnace at a sintering temperature of 1200° C., a sintering time of 15 hours, and a sintering atmosphere of nitrogen. After sintering, the molded body is cooled to room temperature in the muffle furnace and taken out, then put into a molybdenum crucible with a diameter of 92mm, and then the molybdenum crucible is placed in the single crystal furnace, and the single crystal furnace is evacuated to 1×10 -3 Pa.

[0036] Raise the temperature of the single crystal furnace to 1750°C to melt the molded body to obtain a melt. After 40 minutes of heating, the vacuum in the...

Embodiment 2

[0041] The equipment used in this example is the same as in Example 1.

[0042] Take the molded body after sintering in Example 1, put it in a molybdenum crucible, then place the molybdenum crucible in the single crystal furnace, and evacuate the single crystal furnace to 1×10 -3 Pa.

[0043] Raise the temperature of the single crystal furnace to 1750°C to melt the molded body to obtain a melt, and take the seed crystal of the [001] crystal orientation. Slowly lower the seed crystal into contact with the cold core of the melt, and at the same time rotate the seed crystal at a speed of 15r / min, soak the seed crystal in the cold core for 30 minutes and start to shoulder. When putting the shoulders, the lifting speed is 1mm / h, and the power drop speed is 4.5w / h.

[0044] After shouldering, lithium gallate crystals are grown by equal diameter pulling, the seed crystal pulling speed is 5mm / h, and the power drop speed is 5w / h.

[0045] After the growth of the equal-diameter part ...

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Abstract

The invention provides a method for preparing lithium gallate crystals, which comprises the following steps of: mixing Li2CO3 and Ga2O3 serving as raw materials, pressing the mixed materials into a block to obtain a molded body and sintering the molded body; and heating the molded body under vacuum to obtain a melt, putting seed crystals into a cold centre of the melt for soaking and rotating theseed crystals at the same time, shouldering and performing equal-diameter pulling to obtain the lithium gallate crystals. According to the invention, in a sintering process, the purity of the raw materials can be improved, and the volatilization of the crystal growth can be reduced. In addition, the molded body is formed into the melt by heating under vacuum, the seed crystals are put into the cold centre of the melt for soaking and rotated to reduce the non-uniformity of a temperature field, and finally, the lithium gallate crystals can be obtained by shouldering and performing equal-diameter pulling. By putting seeds into the cold centre, the top end of a solid-liquid interface can be superposed with the centre of the centre of seed crystals to prevent the eccentric growth of the crystals, the volatile materials can be discharged smoothly, and thus, the quality of the crystals can be improved.

Description

technical field [0001] The invention relates to the field of artificial crystals, in particular to a method for preparing lithium gallate crystals. Background technique [0002] Lithium gallate crystals belong to the orthorhombic crystal system, and the space group is Pna2 1 , Ga 3+ and Li 3+ Alternately in the tetrahedral center of O, the crystal structure is close to zinc wiltite. Lithium gallate has many advantages and is used in many fields. For example, lithium gallate crystals as doped Cr 4+ The laser crystal host material exhibits unique spectral properties. As another example, lithium gallate crystals have strong piezoelectric polarization, and use piezoelectric materials with great application value. In addition, since the average lattice mismatch between lithium gallate crystal and gallium nitride is only 0.9%, it is more suitable as a substrate material for gallium nitride crystal. [0003] Although lithium gallate crystals have many advantages, the prepara...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C30B29/22C30B15/00
Inventor 杨卫桥王康平李抒智马可军周颖圆叶小钰
Owner SHANGHAI RES CENT OF ENG & TECH FOR SOLID STATE LIGHTING
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