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Lanthanum titanates single-crystal upgrowth technology

A technology of lanthanum titanate and crystal growth, applied in the direction of single crystal growth, single crystal growth, crystal growth, etc., can solve the problems of easy introduction of impurities, difficulty in ensuring composition and structure uniformity, etc.

Active Publication Date: 2009-12-23
苏州晶生新材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although polycrystalline ceramic LTO is easy to prepare, it is easy to introduce impurities during the preparation process, forming a large number of pores, and it is difficult to ensure the uniformity of composition and structure, and these factors play a decisive role in the preparation of high-quality LTO films.

Method used

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  • Lanthanum titanates single-crystal upgrowth technology
  • Lanthanum titanates single-crystal upgrowth technology

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0049] TiO with a purity of 99.9 wt% 2 and 99.999wt% La 2 o 3 Press La 2 Ti 2 o 7 The chemical composition ingredients are mixed, and the mixed powder is ground and mixed evenly on a mortar or grinder, at 2t / cm 2 Pressed into a pellet under isostatic pressure; then placed in a cylindrical crucible together with a seed crystal of the selected orientation . The crucible is placed in the descending furnace and adjusted to a certain height. After the whole system is sealed, it is energized and heated up. The mechanical pump and the diffusion pump are started successively, and the vacuum is pumped to 10 -3 Pa, when the furnace temperature reaches 1500°C, fill it with 99.99% by volume of argon, continue to heat up to 1850°C, melt the raw material and adjust the position of the furnace to melt the top of the seed crystal, perform inoculation and growth, and the temperature gradient of the growth interface is maintained at 30 ℃ / cm, lower the crucible at a rate of 3 mm / h, and gro...

Embodiment 2

[0052] TiO with a purity of 99.99wt% 2 and 99.999wt% La 2 o 3 Press La 2 Ti 2 o 7 The chemical composition ingredients are mixed, and the mixed powder is ground and mixed evenly on a mortar or grinder, at 3t / cm 2 Pressed into cubes under the isostatic pressure; and then placed into a rectangular cylindrical crucible together with a rectangular cylindrical seed crystal in the direction. The crucible is placed in the descending furnace and adjusted to a certain height. After the whole system is sealed, the temperature is energized and the vacuum is pumped to 10 -4 Pa, when the furnace temperature reaches 1600°C, fill it with 99.99% by volume argon, continue to raise the temperature, control the furnace temperature at 1900°C, melt the raw material and inoculate and grow, the temperature gradient of the growth interface is about 60°C / cm, and the temperature gradient is 8.8mm / The crucible is lowered at a rate of h, and a rectangular columnar LTO complete crystal is grown. ...

Embodiment 3

[0054] TiO with a purity of 99.9 wt% 2 and 99.999wt% La 2 o 3 Press La 2 Ti 2 o 7 The chemical composition ingredients are mixed, the mixed powder is ground and mixed evenly on a mortar or grinder, and pressed into a round block; respectively put into three crucibles with a diameter of 70mm, and then placed in a high-temperature drop furnace with three crucible positions, adjust After reaching a certain height, the whole system is sealed and energized to heat up, and then vacuumed to 10 -2 Pa, when the furnace temperature reaches 1700°C, fill it with 99.99% by volume argon, continue to raise the temperature, and control the furnace temperature at 1950°C. Adjust the furnace entry positions of the three crucibles so that the seed crystals in each crucible can be inoculated well. The temperature gradient of the growth interface is about 70°C / cm, and the crucible descending rate is 1.0mm / h. Three cylinders can be obtained at the same time. like LTO crystals. After the cryst...

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Abstract

A lanthanum titanate crystal is provided, the chemical composition is La2Ti2O7, and the crystal is a single crystal. Also provided is a crucible drop method growth technology for growing lanthanum titanate La2Ti2O7 single crystal, comprising the following steps: (1) using TiO2 and La2O3 as initial raw materials, the dosage ratio of the two is according to the chemical composition of La2Ti2O7, mixing evenly, and briquetting; (2) Move the crucible containing the briquette raw material obtained in step (1) to the vacuum drop furnace, heat up the whole system and evacuate it to 10-2-10-4Pa, and charge it when the furnace temperature rises to 1500-1700°C into the inert protective gas, continue to heat up to the set temperature, the set temperature is in the range of 1850-1950 ° C; (3) adjust the position of the crucible in the furnace, so that the raw material and the top of the seed crystal are melted, and the growth of the seed crystal is realized. The growing solid-liquid interface temperature gradient is in the range of 20-80°C / cm, and the crucible descending rate is controlled between 0.2-10mm / h; (4) After the crystal growth is completed, the The temperature of the furnace is lowered to room temperature, and the grown crystal is annealed. The obtained lanthanum titanate single crystal has good crystallization properties, large dielectric constant and high refractive index.

Description

technical field [0001] The present invention relates to a single crystal of lanthanum titanate and a growth method for preparing a single crystal of lanthanum titanate, more specifically to a single crystal of lanthanum titanate with high dielectric and high refractive index, and the growth technology of the single crystal by the crucible drop method . The invention belongs to the field of single crystal growth. Background technique [0002] Lanthanum titanate crystal La 2 Ti 2 o 7 (hereinafter sometimes referred to as LTO) belongs to the monoclinic system, perovskite-like structure, and the space group at room temperature is P2 1 . LTO crystals have good ferroelectric, photocatalytic, and electro-optical properties, and have broad application prospects in the fields of light and electricity. It has a very high Curie temperature (1500°C) and a large coercive field (45kV / cm), and can be used in high-temperature electro-optic devices and information storage, such as high...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C30B29/32C30B15/08
Inventor 吴宪君李新华徐家跃张道标顾宝林
Owner 苏州晶生新材料有限公司
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