Method for reducing breakage rate of quartz tubes during preparation of scintillation single crystals

Abstract

The invention discloses a method for reducing the breakage rate of quartz tubes during the preparation of scintillation single crystals. The method comprises the following steps: drawing a quartz tubeinto a hetero-shaped quartz tube with a thick upper part and a thin lower part, coating the inner wall of the quartz tube with a film, mounting a strain gage on the outer wall of the quartz tube, controlling the growth speed of a single crystal through the feedback of strain amplitude, preventing the breakage of the quartz tube, inverting the hetero-shaped quartz tube after a crystal is formed, and taking out a scintillation crystal after the scintillation crystal is cooled to room temperature. The method has the advantages that the inner wall of the hetero-shaped quartz tube is coated with the film before a single crystal material is loaded, conglutination between the hetero-shaped quartz tube and the produced crystal can be avoided, complete separation of the produced crystal and the hetero-shaped quartz tube body is facilitated, the quartz tube can be prevented from directly extruding the crystal, the method is convenient for reducing micro defects of the crystal, the probability of self-absorption of the crystal is reduced, the cracking risk of the crystal is reduced, the internal performance of the scintillation crystal is obviously improved, in addition, after crystal growthand cooling after accomplished, the quartz tube is not required to be broken to take out the crystal, all that is needed is to open the quartz tube and pour out the crystal, and the quartz tube can be reused after being cleaned.

Description

technical field [0001] The invention belongs to the field of crystal material preparation, in particular to a method for reducing the damage rate of quartz tubes in the preparation of scintillation single crystals. Background technique [0002] Scintillation single crystal materials are usually wide bandgap semiconductor materials. When high-energy photons (such as ultraviolet rays, X-rays, and gamma rays) are incident, a series of complex interactions occur with the lattice of the material, including the photoelectric effect, Compton scattering, and electron pair effects. In this process, the conduction band and valence Many electron-hole pairs are formed in the band and are excited. Electron pairs and holes (eventually forming excitons) then move through the material and are trapped by defects in the forbidden band. Electrons and holes are trapped in the luminescent center and undergo radiative transitions to form scintillation luminescence. By scintillating single crys...

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Problems solved by technology

However, the expansion coefficient of the quartz tube is small, and the linear expansion coefficient is only 5×10 in the range of 0 to 1000°C. -6 K -1 , its volume changes very little with temperature, but the expansion coefficient of scintillation crystal material is low, for example, the expansion coefficient of sodium iodide (NaI) is 47.4×10 -6 K -1 , the volume of scintillation crystal material changes greatly with temperature

The traditional quartz tube is in the shape of a cylinder with a pointed tip at the bottom. Due to the difference in expansion coefficient between the two, during the preparation of scintillation single crystals, the quartz tube is very easy to crack as the temperature changes. Once cracked, the air will flow from the When the cracks in the quartz tube enter the sample, the sample will be completely useless once it comes into contact with the air, resulting in the waste of all raw materials, time and energy consumed in the previous preparation process.

Even if the quartz tube is not cracked during the preparation process, it is still necessary to break the quartz tube to take out the crystal after the preparation is successful, so the quartz tube can only be used once, which will cause great waste

What's more serious is that after the quartz tube is broken, the crystal and the quartz tube are seriously adhered. Due to the adhesion force, the crystal has internal cracks and becomes a waste product. The failure rate of the entire preparation process is extremely high, which will cause a great waste of resources. technical problem

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