高解像度MAS NMR技術を使用して,アニオン導体BaSnF(4) のフッ素亜線状の異なるダイナミクスを解明する
Santanu Chaudhuri1, Francis Wang, Clare P Grey
1Department of Chemistry, State University of New York, Stony Brook, NY 11794-3400, USA.
Journal of the American Chemical Society
|September 26, 2002
まとめ
フッ化物イオン伝導体BaSnF(4) は,2つの異なるフッ化物亜線状を示している. BaとSnの層間の移動性フッ素イオンにより,2Dの伝導性が速くなり,3Dの伝導性が遅くなり,層間のジャンプが必要になります.
科学分野:
- 固体化学 固体化学
- マテリアルサイエンス 材料科学
- 核磁共振スペクトロスコーピーは,核磁共振スペクトロスコーピーを用います.
背景:
- BaSnF ((4) はMSnF ((4) 家族に属し,フッ素と関連したアニオン伝導性で知られています.
- イオンの移動性を理解することは,高度な導電性材料の開発に不可欠です.
- フッ化物イオン伝導体は,電気化学装置の重要な構成要素です.
研究 の 目的:
- 先進的なNMR技術を使用して,BaSnF(4) のフッ化物イオンのダイナミクスを調査する.
- この層状の材料におけるイオン伝導性のメカニズムを解明する.
- 構造的特徴と観察されたイオン移動性と伝導性を相関させる.
主な方法:
- 固体核磁共振 (NMR) スペクトロスコーピー,特に19Fおよび119Sn MAS NMR.
- 幅広い温度範囲 (-150~250°C) でイオンダイナミクスを研究するための変数温度実験.
- 19F-119Sn クロスポラライゼーション (CP) と2D交換 NMR実験で,局所環境とイオン交換を調査する.
主要な成果:
- 2つの異なるフッ素亜網格が特定されました: Ba ((2+) 層の固い亜網格と Ba/Sn 層の間の移動性亜網格です.
- 移動子網で観測された非常に速いイオン運動 ( -100 °Cでの相関時間<3 x 10^-5 s).
- 硬質亜網と移動亜網の間の交換が遅い証拠があり, -150°C以下では動きがほぼ完全に凍結している.
結論:
- この結果は,移動性フッ化物亜網の中で,急速な二次元アニゾトロプ的伝導性のモデルを裏付けている.
- 三次元伝導性は,層間のジャンププロセスがはるかに遅いことで制限されています.
- NMRスペクトロピーは,BaSnFのような複雑な層構造のイオン移動性を効果的に区別し,定量化します.
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