Method for treating crystal growth raw material

Abstract

The invention discloses a process method for crystal growth material that includes the following steps: weighing the raw material according to certain ratio, mixing fully, pressing to 5-20KPa to form needed shape, sintering at 800-1100 degree centigrade, melting the material in crucible under the protection of shielding gas, transferring into growing crucible after melting in sealed environment. The method is suitable for preprocessing of volatility raw material, especially noxious gas volatility raw material.

Description

technical field [0001] The invention relates to a raw material pretreatment method, in particular to a crystal growth raw material processing method. Background technique [0002] Lead tungstate scintillation crystal is a crystal widely used in nuclear imaging equipment such as high-energy physics, positron electron monolayer scanner (PET) and X-CT. The relatively successful method of growing lead tungstate crystals in batches is in a closed crucible The multi-crucible descending method or the multi-crucible temperature gradient method are used to grow lead tungstate and its doped modified crystals. These crystal growth methods all encounter the need to pre-melt the growth raw materials in an oxidizing atmosphere, which will bring obvious benefits: the raw materials for growth can be fully mixed before entering the growth crucible; The volume of good crystals, melts and unmelted raw materials and raw materials before growing crystals will not change significantly in the gro...

AI Technical Summary

Problems solved by technology

This method has two obvious shortcomings: one is to feed oxygen into the entire material furnace, and keep the temperature at 1200°C for half an hour, which is very difficult in actual operation, and the muffle furnace usually used to heat the material cannot Guaranteed to be airtight and airtight, so the oxygen introduced into the furnace will escape the furnace of chemical materials in large quantities at high temperatures, which cannot fully achieve the purpose of preventing non-stoichiometric volatilization of melt raw materials, and if the oxygen introduced into the furnace inhibits the composition of raw materials Non-stoichiometric volatilization, the raw material must be open during the melting process, with the large amount of oxygen in the furnace escaping, the volatilization of components in the raw material will appear and accelerate, making the raw material in the melt deviate from the stoichiometric ratio, affecting the quality of crystal growth, and Cause serious environmental pollution; The second is that in the process of transferring raw materials after melting, the patent applicant usually adopts the dumping method. After the raw materials are melted and kept at a constant temperature for a period of time, the furnace door is opened at a high temperature, and the crucible of the chemical material is clamped with crucible clamps. Quickly move the crucible to the vicinity of the growth crucible, and quickly pour the raw materials into the growth crucible. The growth crucible is fixed with a lining mold, and most of it is immersed in water, so that the molten material can be cooled rapidly. Measuring volatility, especially if there are particularly volatile doping components such as PbF in the raw material 2 The situation is even more serious. A large amount of non-stoichiometric volatilization causes the raw materials to deviate from the stoichiometric composition to a certain extent, and causes serious environmental pollution. Moreover, this operation relies heavily on the proficiency of the operator, and any delay will cause the molten material to be poured too late. The temperature is cooled to make part of the raw materials solidify in the crucible, which requires re-chemical and transfer, etc., and operation errors will cause burns and other industrial accidents, endangering personal safety