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Development of a New Crystal Growth Technique using Preitectic Reactions

利用预晶反应开发新的晶体生长技术

基本信息

批准号：
07455003
负责人：
TAKEI Humihiko
金额：
$ 5.44万
依托单位：
Osaka University, Graduate School of Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07455003/
关键词：
Crystal Growth Peritectic Reaction Oxide Crystals Incongruent Compounds Oxide Superconductors Low Dimensional Oxides Phase Relation Ostwald Ripening 鎖状硅酸塩酸化物結晶分解溶融型化合物固液混合状態

项目摘要

Peritectic reactions which are commonly observed upon solidification of incongently molten liquid have been applied for growth of large oxide crystals. Recrystallization under the Ostwald ripening mechanism proceeded in keeping of such a peritectic condition where peritectic solids coexisted with liquid. Small particles with peritectic layrs tended to diminish by resolution into the melt due to high surface free energies and large, well-habited crystals surrounded by developed surfaces with infinit curvatures became large. The merits of using this technique are that materials with high melting, high vaporizing or incongruent melting properties can be crystallized, that the growth procedure is so simple as usual flux methods and that undesired contamination from crucible materials can be avoided because of low growth temperatures. Here we applied this technique to oxides such as oxide superconductors and low dimensional oxides, and succeeded in growing mm-sized, high quality crystals of YBa_2Cu_3O_x, Tl_2Ba_2Ca_2Cu_3O_<10>, Tl_2Ba_5Cu_4O_<x, > SrCuO_2, Y_2Cu_2O_5, CuFeO_2, PdCoO_2 PtCoO_2 and MgSiO_3. Using these crystals, we measured the crystal structures, magnetic and electric properties. To clarify the growth mechanism more precisely, we have constracted a high temperature X-ray diffraction apparatus with a rapid counting system for analyzing the phase change rates in peritectic conditions. The results indicated that the diffusion in the liquid phase was the rate determining process rather than in the soild phase. Detailed phase relations in the Bi-Sr-Cu-O,Bi-Sr-Ca-Cu-O and Bi-Pb-Sr-Ca-Cu-O systems have been also established between 1273K and room temperature using the same spparatus in air.

通常在不一致的熔融液体凝固时观察到的包晶反应已应用于大氧化物晶体的生长。在奥斯特瓦尔德成熟机制下的再结晶是在包晶固体与液体共存的条件下进行的。由于表面自由能高，具有包晶层的小颗粒在进入熔体时趋于减少，而被具有无限曲率的发达表面包围的大的、习惯良好的晶体变大。使用该技术的优点是，高熔点、高汽化或不均匀熔点的材料可以结晶，生长过程与通常的助熔剂方法一样简单，并且由于生长温度低，可以避免坩埚材料的不希望的污染。本文将该技术应用于氧化物超导体和低维氧化物中，成功地生长出了YBa_2Cu_3O_x、Tl_2Ba_2Ca_2Cu_3O_<10>、Tl_2Ba_5Cu_4O_<x、> SrCuO_2、Y_2Cu_2O_5、CuFeO_2、PdCoO_2 PtCoO_2和MgSiO_3等尺寸的高质量晶体。利用这些晶体，我们测量了晶体结构、磁性和电性能。为了更精确地阐明生长机制，我们构建了一个带有快速计数系统的高温x射线衍射仪，用于分析包晶条件下的相变速率。结果表明，液相扩散是速率决定过程，而非固相扩散。在1273K至室温的温度范围内，采用相同的空分，建立了Bi-Sr-Cu-O、Bi-Sr-Ca-Cu-O和Bi-Pb-Sr-Ca-Cu-O体系的详细相关系。