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Growing method of lanthanum aluminate crystal

A growth method and technology of crystal growth, applied in the directions of crystal growth, single crystal growth, single crystal growth, etc., can solve problems such as difficulty in ensuring composition and structure uniformity

Active Publication Date: 2008-10-08
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 lanthanum aluminate 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 lanthanum aluminate films

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] Al with a purity of 99.999wt% 2 o 3 and 99.999wt% La 2 o 3 by LaAlO 3 The chemical composition ingredients are mixed, and the mixed powder is ground and mixed evenly on a mortar or grinder, at 2.5t / 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 99.99V% argon, continue to heat up to 2200°C, melt the raw material and adjust the position of the furnace to melt the top of the seed crystal, and perform seed growth, and the temperature gradient of the growth interface is maintained at 40°C / cm or so, lower the crucible at a rate of 3mm / h to grow cylindrical lanth...

Embodiment 2

[0047] Al with a purity of 99.999wt% 2 o 3 and 99.999wt% La 2 o 3 by LaAlO 3 The chemical composition ingredients are mixed, the mixed powder is ground and mixed evenly on a mortar or grinder, and the mixture is mixed at 3.5t / 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 99.99V% argon, continue to heat up, control the furnace temperature at 2150°C, melt the raw materials and inoculate and grow, the temperature gradient of the growth interface is about 55°C / cm, and the growth rate is 8.8mm / The crucible is lowered at a rate of h, and a complete crystal of rectangular columnar lanthanum aluminate is gro...

Embodiment 3

[0049] Al with a purity of 99.999wt% 2 o 3 and 99.999wt% La 2 o 3 by LaAlO 3 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 99.99V% argon, continue to raise the temperature, and control the furnace temperature at 2250°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. lanthanum aluminate crystals. After the crystal g...

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Abstract

The invention provides a bridgman growth method for the growth of lanthanum aluminate LaAlO3 crystals, which includes the following steps. (1) The Al2O3 and the La2O3 are taken as the raw materials in which the quantity ratio is in accordance with the chemical composition of LaAlO3, mixed and pressed. (2) The crucible loaded with the raw material briquetting is moved inside a vacuum decline furnace. The temperature is increased to 10-2-10-4Pa through the vacuum pumping. The insert protection gas is charged when the furnace temperature is increased to 1500 to 1700 DEG C, and then the temperature in continuously increased to 2100 to 2300 DEG C. (3) The raw materials and the top of the seed crystals are in melting so that the inoculation growth can be achieved. The temperature gradient of solid-liquid interface for the crystal growth is within a framework of 25 to 85 DEG C / cm, and the crucible decline rate is between 0.2 to 10 mm / h. (4) After the crystal growth is completed, the furnace temperature is reduced to a room temperature with the speed of 30 to 100 DEG C / h. The obtained lanthanum aluminate crystals have excellent crystal properties, low dielectric constant and dielectric loss as well as medium refractive index.

Description

technical field [0001] The present invention relates to a growth method of lanthanum aluminate crystal, more specifically to lanthanum aluminate crystal with low dielectric constant, low dielectric loss and medium refractive index, and the growth method of the crystal by crucible drop method. The invention belongs to the field of crystal growth. Background technique [0002] Lanthanum aluminate crystal LaAlO 3 It belongs to the monoclinic crystal structure, the space group is R-3c, and its unit cell parameters are a=0.537nm, b=0.537nm, c=1.315nm. The lanthanum aluminate crystal at room temperature has a pseudocubic structure, which is close to the ideal perovskite Structure, phase transformation occurs at about 530 ° C, and becomes a cubic phase structure. The melting point of lanthanum aluminate crystal is about 2100°C, and the density is 6.52g / cm 3 . Due to the particularity of the structure of the lanthanum aluminate crystal, it has a good lattice matching for a varie...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C30B29/24C30B11/00
Inventor 吴宪君李新华何庆波
Owner 苏州晶生新材料有限公司
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