Method for growing large-size high-temperature oxide crystal through for top-seeded temperature gradient technique

Abstract

The invention discloses a method for growing large-size high-temperature oxide crystal through a top-seeded temperature gradient technique. The method comprises steps of placing raw materials in a crucible of a multi-chamber crystal furnace, fixing seed crystal on a bottom end portion of a seed crystal rod of a seed crystal lifting rotary mechanism, and melting raw materials in the crucible to form a melting liquid; gradually reducing the heating power, enabling the melting liquid temperature to be a little higher than a melting point and trend to be stable, and observing the cold point position of the melting; washing the seed crystal; moving a cold point to the central position of the seed crystal; completely coinciding the central line of the seed crystal after being washed with the cold point of the melting liquid and keeping a constant temperature; seeding; necking down; shouldering; performing an equal-diameter process; and performing in situ annealing. Accordingly, a Kyropoulos method, a Czochralski method, a heat exchanging method, a temperature gradient technique and a Bridgman method are combined together, and the large-size high-temperature oxide crystal is produced.

Description

technical field [0001] The invention discloses a method for growing high-temperature oxide crystals, in particular a method for growing large-sized high-temperature oxide crystals by a top seed crystal temperature gradient method. Background technique [0002] At present, there are four main methods for growing high temperature oxide crystals: pulling method, heat exchange method, crucible descent method and temperature gradient method. [0003] 1. The pulling method was invented by Czochralski in 1918, so it is also called "Chuklarski method", or CZ method for short. It is a method of growing crystals by pulling the seed crystal from the melt. The most dominant method for single crystals. The molten material is contained in the heated crucible, and the seed rod is inserted into the melt from top to bottom with the seed crystal. Since the melt near the solid-liquid interface maintains a certain degree of supercooling, the melt crystallizes along the seed crystal, and then ...

AI Technical Summary

Problems solved by technology

[0011]2. Due to the large gradient, the growth interface is excessively raised, the thermal stress is large, and the dislocation value increase causes the dislocation density to be too large, and the single crystal property is not good;

[0012]3. Large temperature gradient and high energy consumption

[0019] 1. The requirements for equipment are high, the whole process is complex, the crystal growth period is long, a large amount of helium is required as a coolant, and the cost is high

[0020]2. The temperature gradient distribution is opposite to the gravity field, which is not conducive to the removal of impurities;

[0021] 3. The crystal is in contact with the crucible, the stress of the crystal is large, and it is easy to parasitize and nucleate to cause polycrystal;

[0022]4. Crystal growth cannot be controlled and observed in real time;

[0023]5. The growth interface is too convex, with large thermal stress and dislocation

[0032]1. It is not suitable for materials with negative expansion coefficient, and materials with liquid density greater than solid density;

[0033]2. Due to the action of the crucible, it is easy to form stress, parasitic nucleation and pollution;

[0034]3. Not easy to observe;

[0035]4. There is mechanical disturbance in the descending mechanism

[0042]1. The temperature gradient distribution is opposite to the gravity field, which is not conducive to the removal of impurities;

[0043] 2. The crystal is in contact with the crucible, the stress of the crystal is large, and it is easy to parasitize and nucleate to cause polycrystal;

[0044]3. Crystal growth cannot be controlled and observed in real time;

[0045]4. The growth interface is too convex, with large thermal stress and dislocation

[0047] In the existing crystal growth methods, there is no method that can artificially control the crystal growth interface in real time according to the different stages of crystal growth