Growth process of magnesium silicate crystal with doped quadrivalent chromium

Abstract

A method for growing tetravalent chromium-doped magnesium silicate crystals adopts a radio frequency induction heating and pulling method. A medium-frequency induction heating pulling furnace with a nitrogen inlet valve, an oxygen inlet valve and a gas outlet valve on the furnace body is used. A protective layer of mixed powder of iridium powder and zirconia powder is sprayed on the outer surface of the iridium crucible. During the process of heating up, seeding, necking, and shouldering, only nitrogen is filled in the furnace body, and it is kept in a flowing state. Before starting equal-diameter growth, open the oxygen inlet valve, and the mixed gas of oxygen and nitrogen is fed into the furnace body according to the volume percentage of the two gases, and is kept in a flowing state. After isometric growth is complete, close the oxygen inlet valve. The flowing nitrogen atmosphere was still maintained during the finishing process. After finishing, the temperature starts to drop, and the furnace body is kept under vacuum until it drops to room temperature. Compared with the prior art, the protective layer of the iridium crucible is stronger, and the oxygen-containing time in the furnace body is shortened, thereby reducing the oxidation and volatilization of the iridium crucible at high temperature. The single growth loss of the iridium crucible is only 3 grams.

Description

Technical field: [0001] The invention relates to a growth method of tetravalent chromium-doped magnesium silicate crystals, in particular to a method for growing tetravalent chromium-doped magnesium silicate crystals to protect an iridium crucible, and has good application prospects in the field of crystal growth. Background technique: [0002] Magnesium silicate doped with tetravalent chromium (Cr 4+ : Mg 2 SiO 4 ) crystals must be grown under an oxidizing atmosphere, but under an oxidizing atmosphere, the iridium crucible is severely oxidized and the loss is large, which increases the cost of crystal growth. In 1993, Japanese scientist Y. : Mg 2 SiO 4 Laser crystals, obtained a single crystal with a size of Φ35×100mm (see prior art [1] Y.Yamaguchi, "The behavior of chromium ions in forsterite" published in the International Journal of Crystal Growth, No. 128, No. 1993 pp. 996-1000). In 1992, Chinese scientist Yan Shenghui and others provided a "method for protecting ...

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Problems solved by technology

[0002] Magnesium silicate doped with tetravalent chromium (Cr 4+ : Mg 2 SiO 4 ) crystals must be grown under an oxidizing atmosphere, but under an oxidizing atmosphere, the iridium crucible is severely oxidized and the loss is large, which increases the cost of crystal growth. In 1993, Japanese scientist Y. : Mg 2 SiO 4 Laser crystals, obtained a single crystal with a size of Φ35×100mm (see prior art [1] Y.Yamaguchi, "The behavior of chromium ions in forsterite" published in the International Journal of Crystal Growth, No. 128, No. 1993 996-1000 pages)

In 1992, Chinese scientist Yan Shenghui and others provided a "method for protecting iridium crucibles from growing tetravalent chromium-doped high-temperature oxide crystals", application number 92108460.9, publication number CN1080334A, which used plasma spraying technology to spray a zirconia protective layer on the outer wall of iridium crucibles. The method of chemicalizing materials under a neutral atmosphere and maintaining the growth of crystals under an oxygen atmosphere greatly reduces the iridium volatilization loss, and the single growth loss is about 6 grams, but this method has obvious disadvantages: (1) the zirconia coating is easy During growth, especially when the temperature rises and falls, the crucible will be separated from the crucible when the temperature changes greatly, which will cause serious loss of the iridium crucible; (2) the oxygen-containing time in the atmosphere during the crystal growth stage is too long, and the loss of the iridium crucible is still large; (3) at the beginning The oxygen content in the stage is sufficient, and with the consumption of oxygen content, the Cr in the crystal 4+ The ion concentration is getting lower and lower, making the concentration extremely uneven, which not only affects the availability of the crystal, but also due to Cr 4+ The inhomogeneity of ion concentration seriously affects the laser performance of the crystal

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