Ni2In型の六角構造を持つ結合されたMnCoGeベースの化合物の巨大な負の熱膨張
Ying-Ying Zhao1, Feng-Xia Hu, Li-Fu Bao
1Beijing National Laboratory for Condensed Matter Physics and State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences , Beijing 100190, P. R. China.
Journal of the American Chemical Society
|January 29, 2015
まとめ
MnCoGe化合物は,構造的移行を通して巨大な負の熱膨張 (NTE) を表します. エポキシ粉末との結合は,移行を拡大し,NTEの性能と動作温度範囲を大幅に改善します.
科学分野:
- マテリアルサイエンス 材料科学
- 凝縮物質物理学 凝縮物質物理学
- 固体化学 固体化学
背景:
- MnCoGeベースの化合物は,マルテンシート構造的移行に関連した巨大な負熱膨張 (NTE) を表しています.
- 以前の研究は,磁熱効果に焦点を当て,限られた移行温度ウィンドウによるNTEの可能性を無視した.
- これらの化合物の固有の脆さは,それらの実用的な応用を妨げています.
研究 の 目的:
- MnCoGeベースの化合物の負の熱膨張 (NTE) 特性を強化する.
- NTE.の運用温度窓を拡大する.
- 構造転換とNTEに対する残留ストレスの影響を調査する.
主な方法:
- 高解像度の中性子 difraktion 構造的移行とユニット細胞の体積の変化を分析する.
- 粉末型MnCoGeベースの材料に少量のエポキシ (3-4%) を加える.
- 結合されたサンプルにおける熱膨張係数と動作温度ウィンドウの特性.
主要な成果:
- 巨大なNTEは,エポキシ結合による残留ストレス導入によって達成され,構造的移行を拡大しました.
- 平均線形NTE係数 (α̅) は,210 Kの窓 (122 332 K) 上で−51.5 × 10−6/Kで,MnCo0.98Cr0.02Ge.Ge.で観測されました.
- 室温 (250305 K) 近くでは,ほぼ恒定的α値である -119 × 10−6/K が達成され,優れた性能を示しています.
結論:
- エポキシ誘発の残留ストレスは,フェーズ移行を効果的に拡大し,NTEのパフォーマンスを大幅に改善します.
- 幅広い動作温度窓と高い係数を含む達成されたNTE性能は,以前に報告された材料を上回ります.
- これらの強化されたMnCoGeベースの材料は,NTEを必要とするアプリケーション,特に陽性熱膨張を補償するための重要な潜在能力を示しています.
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