Horizontal growth method for lead tungstate scintillation crystal
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A scintillation crystal and growth method technology, applied in crystal growth, single crystal growth, single crystal growth, etc., can solve problems such as crystal cracking, affecting PWO crystal yield, increasing crystal cost, etc., to achieve automation, cost reduction, and simplification Process effect
Active Publication Date: 2010-02-10
WENZHOU UNIVERSITY
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Problems solved by technology
This process not only increases the cost of crystals, but also crystal cracks are prone to occur during the p
Method used
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Embodiment 1
[0022] (1) Get 1470 grams of 99.999% pure PbO and 1530 grams of 99.999% pure WO 3 After the powder is dehydrated, mix it evenly, place it in a crucible and pre-fire the material at 800°C for 4 hours, then raise the temperature to 1200°C to melt the raw material, keep it warm for 30 minutes, quickly inject it into the mold, and cool down to obtain a polycrystalline ingot;
[0023] (2) Select the existing lead tungstate scintillation crystal, and precisely orientate it with the X-ray orientation instrument, and the orientation is . After cutting, grinding and cleaning, a PWO with a cross-section of 30mm×30mm and a length of 50mm is obtained as a seed crystal;
[0024](3) The seed crystal obtained in step (2) and the polycrystalline ingot obtained in step (1) are packed into a platinum crucible, the polycrystalline ingot fills the crucible, and the seed crystal is placed in a suitable place on the edge of the crucible in the direction of horizontal movement of the crucible. posit...
Embodiment 2
[0027] Reaction condition and operation are with embodiment 1, difference is, in the raw material in step (1), add 8gPbF 2 ; In step (2), select PWO with orientation , cross-section 20mm×40mm, and length 50mm as the seed crystal. Other operations and reaction conditions were the same as those in Example 1, and a PWO crystal with a size of 30mm×60mm×200mm was grown. The obtained crystal is a high-performance PWO crystal, which can meet the application requirements of high light output.
Embodiment 3
[0029] The reaction conditions and operations are the same as in Example 1, except that in step (2), PWO with orientation, cross-section of 30mm×30mm, and length of 50mm is selected as the seed crystal. A wedge-shaped Pt crucible was adopted, and other operating and reaction conditions were the same as in Example 1, and a wedge-shaped PWO crystal was grown. The obtained wedge-shaped PWO crystal can meet the requirements of high-energy physical detection for wedge-shaped PWO crystals and other special shapes.
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Abstract
The invention discloses a horizontal growth method for a lead tungstate scintillation crystal. The method includes the following steps: after being dewatered, PbO and WO3 powder materials with 99.999percent of purity are proportioned according to a stoichiometric ratio, are uniformly mixed, and then are arranged in a copple to be heated, temperature is raised so as to melt the raw materials, andthen the melted raw materials are injected into a mould; after temperature reduction, a polycrystalline ingot can be obtained, the obtained polycrystalline ingot is arranged in the copple, homogeneouscrystals which are prepared in advance are used as seed crystals, the seed crystals are inoculated in the copple and grow directionally, the growth rate ranges from 0.4 to 0.9 mm/h, and the temperature gradient of a growth interface ranges from 20 to 30 DEG C/ cm; and after the growth of the crystals, the obtained PWO crystals and the copple are moved to a low temperature region to be processed by annealing so as to eliminate the thermal stress and to reduce the crystal cracking. The method has the following advantages: tabular crystals with different sizes can be grown, in situ annealing canbe realized, different gas atmospheres can be led inside for crystal annealing, and the operation can be accomplished at one step, thereby simplifying the working procedure of crystal growth, reducing the cost and contributing to the realization of crystal industrialization.
Description
technical field [0001] The invention relates to a method for horizontal growth of lead tungstate scintillation crystals, in particular to a new technology for growing lead tungstate scintillation crystals of various shapes in a horizontal crystal growth furnace, which belongs to the field of crystal growth. Background technique [0002] Lead Tungstate PbWO 4 (PWO for short) crystal is a new type of scintillation crystal material developed in the early 1990s. It has the advantages of high density, high absorption coefficient, short radiation length, high radiation hardness, fast luminescence attenuation and low cost. It is one of the preferred high-energy particle detection materials in the field. In recent years, it has also received widespread attention as a potential nuclear medical imaging material and has a huge potential application market. In the past ten years, PWO crystal growth technology has made great progress, and the main growth technologies include the pulling...
Claims
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Application Information
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