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Crucible for preparing large-section lead tungstate crystal and crystal growth method

A surface lead tungstate, crystal growth technology, applied in the direction of crystal growth, single crystal growth, single crystal growth, etc., can solve the problem of easy cracking of crystals, achieve the effect of reducing thermal stress and avoiding the problem of crystal cracking

Active Publication Date: 2017-05-31
SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This requires the growth of PWO crystals with large cross-sections. However, due to the structural characteristics of PWO crystals themselves, the crystals are very easy to crack during the growth of PWO crystals with large cross-sections by traditional methods, making the preparation of PWO crystals with large cross-sections very difficult and challenging. There are no public reports of PWO crystals with a cross-sectional size greater than 55 mm

Method used

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  • Crucible for preparing large-section lead tungstate crystal and crystal growth method
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  • Crucible for preparing large-section lead tungstate crystal and crystal growth method

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preparation example Construction

[0035] Preparation of the above-mentioned PWO starting material. High-purity PbO, WO 3 The powder molar ratio is 1:1 and evenly mixed to obtain the PWO raw material. Or wash, dry and pulverize PWO single crystal as PWO raw material. As an example, PbO with a purity of 4N, WO 3 The powder is uniformly mixed at a molar ratio of 1:1, or small pieces of PWO single crystal are washed, dried, and crushed, and used as PWO raw material (powder or single crystal crushed material). Because the convective movement of the raw materials after melting in the furnace can make the raw materials mix evenly and fully react, so when selecting powder materials PbO, WO 3 The important thing is the purity, and the purity of 4N or higher is generally used. When using single crystal crushed material, there is no specific requirement for the particle size of the single crystal crushed material, it is suitable for loading into a crucible, and it is generally crushed to a particle size of <10mm.

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Embodiment 1

[0045] A metal platinum sheet with a thickness of 0.14mm is used to make a crucible with two shoulders with a circular cross-section. The size of the crucible seed crystal segment is φ15mm×50mm, and the angles of the two shoulders are both 30°. The height of the section shoulder is 15mm, the size of the equal-diameter section between the two shoulder sections is φ38mm×20mm, and the size of the upper equal-diameter section is φ55mm×320mm;

[0046] After the crucible descends and begins to grow crystals, the seed crystal segment grows at a rate of 1.6 mm / h, the first-stage shoulder segment grows at a rate of 1.0 mm / h, and the equal-diameter segment grows at a rate of 1.2 mm / h. Both the second-level shoulder section and the upper equal-diameter section grow at a descending rate of 0.8mm / h;

[0047] After the growth was completed and naturally cooled to room temperature, the crucible was taken out and peeled off to obtain a PWO crystal of φ55mm×210mm.

Embodiment 2

[0049] A metal platinum sheet with a thickness of 0.14mm is used to make a two-section shoulder-shoulder rectangular cross-section crucible, and the size of the crucible seed crystal section is 20×20mm 2 ×60mm, the angle of the two shoulders is 30°, the height of the first shoulder is 20mm, the height of the second shoulder is 15mm, and the size of the equal-diameter section between the two shoulders is 43×43mm 2 ×20mm, the size of the upper equal-diameter section is 60×60mm 2 ×250mm;

[0050] During the crystal growth process, the seed segment grows at a rate of 1.2mm / h, the first-stage shoulder segment grows at a rate of 0.8mm / h, the equal-diameter segment grows at a rate of 1.0mm / h, and the second The step shoulder section grows at a rate of 0.6mm / h; the upper equal diameter section grows at a rate of 0.8mm / h;

[0051] End of growth, get 60×60mm 2 ×160mm PWO crystal.

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Abstract

The invention relates to a crucible for preparing large-section lead tungstate crystal and a crystal growth method. The crucible comprises a crystal seed section for placing crystal seeds, as well as more than or equal to two diameter enlarging sections and equal diameter sections located behind the crystal seed section and arranged alternately, wherein the diameters of the equal diameter sections are sequentially increased. For the crucible, alternated design of multiple diameter enlarging sections and equal diameter sections is adopted, so that the defects and thermal stress generated in the growth process of the diameter enlarging sections are sufficiently eliminated and reduced in the equal diameter sections, cracking caused by continuous accumulation of defects and stress in single diameter enlarging growth is avoided, and complete crystal is prepared.

Description

technical field [0001] The invention belongs to the technical field of crystal growth, in particular to a method for growing large-section lead tungstate (PbWO 4 , referred to as PWO) crystal crucible and growth of large cross-section lead tungstate (PbWO 4 , referred to as PWO) crystal method. Background technique [0002] Scintillation crystal is a photofunctional material that can convert the energy of high-energy particles or high-energy rays (X-rays, γ-rays, etc.) into ultraviolet or visible light. And silicon photodiode (SPD) and other components of the detector are widely used in high-energy physics, nuclear physics, nuclear medical imaging, security inspection and industrial CT and other fields. [0003] Lead tungstate (PbWO 4 , referred to as PWO) crystal as a new type of scintillation crystal, it has high density (8.28g / cm3), short irradiation length (0.87cm) and Moliere radius (2.12cm), which can make the detection equipment using it compact in structure and re...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C30B11/00C30B29/32
CPCC30B11/002C30B29/32
Inventor 陈良袁晖熊巍周尧
Owner SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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