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Crystal growth atmosphere for oxyorthosilicate materials production

A technology of orthosilicate and crystal, which is applied in the field of crystal growth and can solve problems such as reduced scintillation efficiency

Inactive Publication Date: 2012-05-30
SIEMENS MEDICAL SOLUTIONS USA INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This results in reduced scintillation efficiency and an undesired continuation of the crystal's glow, commonly known as afterglow

Method used

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  • Crystal growth atmosphere for oxyorthosilicate materials production
  • Crystal growth atmosphere for oxyorthosilicate materials production
  • Crystal growth atmosphere for oxyorthosilicate materials production

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Embodiment Construction

[0011] Controlling the atmosphere above the melt during crystal growth using methods such as the Chowklarski method can be critical to controlling growth stability and controlling the properties of the growing crystal. Especially in the growth of rare earth oxyorthosilicate scintillation crystals, careful control of the atmosphere and melt composition can simultaneously minimize at least three problems in these crystal growths.

[0012] The first problem is that the grown crystal contains oxygen vacancies, which reduce the crystal's scintillation efficiency and cause an undesired crystal continuation known as afterglow. These oxygen vacancies may arise from oxygen deficiency during crystal growth. Rare earth oxyorthosilicate scintillation crystals can be prepared by melting rare earth compounds (such as oxides) and silicon oxides (such as SiO 2 ) prepared by melt growth. Melting these substances may require temperatures of 2000°C or higher. At this temperature, it is advisa...

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Abstract

A method of growing a rare-earth oxyorthosilicate crystal, and crystals grown using the method are disclosed. The method includes preparing a melt by melting a first substance including at least one first rare-earth element and providing an atmosphere that includes an inert gas and a gas including oxygen.

Description

technical field [0001] This application relates to crystal growth. Background technique [0002] In certain methods of growing crystals, such as the Chowklarski method, a seed crystal is brought into contact with the surface of a melt and then pulled from the melt. When the seed crystal is pulled, crystals grow on it. The seed crystal and growing crystal sometimes also rotate about a vertical axis when pulled. Growth instability often occurs when using this technique to grow large crystals. For example, crystals may start to grow in a helical shape rather than the desired cylindrical shape. Growth instability may cause stress due to deviations in the crystal's internal thermal expansion coefficient, which may lead to crystal cracking. Such cracking is more likely to occur when there are large temperature gradients in the melt and above the melt in the atmosphere in which the crystals grow. [0003] Sufficient temperature gradients, accumulation of impurities in the melt...

Claims

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Application Information

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IPC IPC(8): C30B27/02C30B29/34
CPCC30B29/34C30B15/02C09K11/77742C09K11/77062C30B15/04
Inventor M.S.安德里科P.舒普里琴斯基A.A.凯里
Owner SIEMENS MEDICAL SOLUTIONS USA INC