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圧力によって誘発される相変異と,中性基導体の金属化
Joanne W L Wong1, Aaron Mailman, Kristina Lekin
1Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada.
Journal of the American Chemical Society
|January 10, 2014
まとめ
圧力は,オクソベンゼンブリッジの1,2,3-ビスディシアゾリル基導体3aをモット・インソレーターから金属に変形させます. この段階の移行は,構造的変化と伝導性の大幅な増加を伴う.
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
- クリスタルグラフィーです.
- オーガニック・エレクトロニクス
背景:
- オクソベンゼンブリッジされた1,2,3-ビスディシアゾリル基導体3aは,圧力に依存する性質を示している.
- ラジカル導体における相変化を理解することは,新しい電子材料の開発に不可欠です.
研究 の 目的:
- 変圧下における根幹導体3aの結晶構造と電荷輸送特性を調査する.
- 圧力による相変化と金属状態の形成のメカニズムを解明する.
主な方法:
- 高圧X線微分法で結晶構造 (α,β,γ相) を決定する.
- 電気伝導性の測定は,様々な圧力や温度で行われます.
- 高圧赤外線吸収および反射スペクトロスコーピー.
- 電子構造分析のための密度関数理論 (DFT) 計算.
主要な成果:
- 圧縮により,α相 (Fdd2) からβ相 (Pbn21) に約3〜4GPaで,さらに8GPaでγ相 (Pbn21) に相移行が誘導されます.
- 構造的変化は,ラッフルされたリボンの"アイロニングアウト"を伴うため,より平面的な根本的な取り決めにつながります.
- 電気伝導性は,圧力が4GPaを超えると3倍の大きさで増加し,アクティベーションエネルギーは0に低下します.
- 4-5GPa近くのモット・ハバード・ギャップの閉塞は,金属状態への移行を示しています.
結論:
- ラジカル導体3aは,比較的低い圧力下では金属状態に容易に移行する.
- 低地にあるLUMOと3aの高い電子親和度は,電子の柔らかさと低クーロンポテンシャル (U) に寄与する.
- 圧力下での結晶軌道混合 (SOMO/LUMO) は,金属状態の形成を促進します.
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