Gd5Si2Ge2の高温相変化について
Yurij Mozharivskyj1, Alexandra O Pecharsky, Vitalij K Pecharsky
1Ames Laboratory, Materials and Engineering Physics Program, Iowa State University, Ames, Iowa 50011-3020, USA.
Journal of the American Chemical Society
|January 6, 2005
まとめ
Gd(5) Si(2) Ge(2) の相変化は,約300~320°Cで発生する. 酸素や窒素のような不純物質は,以前の予測に反して,この移行に大きく影響します.
科学分野:
- 材料科学 材料科学とは
- 固体物理 固体物理学
- クリスタログラフィーです.
背景:
- Gd(5) Si(2) Ge(2) のようなガドリニウム基化合物は,主要な巨大磁熱物質である.
- フェーズトランジションの理解は,磁気冷却アプリケーションの最適化に不可欠です.
研究 の 目的:
- Gd(5) Si(2) Ge(2) でのモノクリニックからオルソロンビック (β->ガンマ) 段階の移行を調査する.
- この移行における間接的不純物の影響を調べる.
主な方法:
- インシット高温単結晶X線 difraktion.
- 汚染を防ぐために,特殊な結晶装着技術の開発.
主要な成果:
- ベータ->ガンマ変換は,加熱とゆっくりとした冷却で300~320°Cの間で可逆的に発生するが,急速な冷却では不可逆的に発生する.
- 予測に反して,SiとGeの原子の分布は相ごとに一貫しています.
- 不純物,特に酸素と窒素は,過渡温度を大幅に変化させ,空気の存在で600°Cで完了するだけです.
結論:
- スラブ間の空隙に収まっている間位汚染物質は,Gd(5) Si(2) Ge(2) の安定性と移行行動において重要な役割を果たします.
- この研究は,原子分布と不純物効果に関する以前の理論モデルに異議を唱える.
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