印象的な構造的多様性とポリモルフィズムがモジュール化合物ABi3Q5 (A = Rb, Cs; Q = S, Se, Te) に見られる
Lykourgos Iordanidis1, Daniel Bilc, Subhendra D Mahanti
1Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
Journal of the American Chemical Society
|November 6, 2003
まとめ
新しいアルカリ金属ビスムートカルコゲニド化合物,ABi3Q5は,多様な構造と狭い帯のギャップを示しています. gamma-RbBi3S5はセレニウムアナログと比較して優れた熱安定性を示しており,高度な材料の応用の可能性を示しています.
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
- 無機化学 無機化学とは
背景:
- 一般式ABi3Q5の化合物で,Aはアルカリ金属,Qはカルコゲンであり,構造的な多様性が顕著である.
- これらの材料の構造-特性関係を理解することは,新しい機能的材料の開発に不可欠です.
研究 の 目的:
- ABi3Q5ファミリー内の新しい化合物を合成し,特徴づけ,構造的多様性と電子特性に焦点を当てます.
- 選択された化合物の熱安定性と電子帯域構造を調べる.
主な方法:
- アルカリ金属カルコゲニドとビスムートカルコゲニドを用いた高温合成 (>650°C).
- 構造的決定のための単結晶X線 difraktion.
- 光学帯域ギャップ測定と電子特性の密度関数理論 (DFT) 計算.
主要な成果:
- 7つの化合物が合成されました:ガンマ-RbBi3S5,アルファ-RbBi3Se5,ベータ-RbBi3Se5,ガンマ-RbBi3Se5,CsBi3Se5,RbBi3Se4Te,そしてRbBi3Se3Te2.
- 化合物は3Dトンネルまたはラメラ構造を示し,特定の結晶学的データが提供されます.
- すべての合成化合物は,狭帯域ギャップ半導体 (0.4-1.0 eV) である.
- gamma-RbBi3S5はセレニウム同位体よりも高い熱安定性を示しました.
- DFTの計算は,間接的な帯域のギャップを確認し,相対的な熱力学的安定性の評価を支持しました.
結論:
- ABi3Q5ファミリーは,構造的複雑性と調節可能な電子特性を探求するための豊富なプラットフォームを提供します.
- 構造の変化は,熱安定性などの材料特性に大きな影響を与えます.
- これらの狭帯域差半導体は,様々な電子機器のアプリケーションの有望さを示しています.
関連する概念動画
02:52VSEPR Theory and the Basic Shapes
Overview of VSEPR Theory
04:01VSEPR Theory and the Effect of Lone Pairs
Effect of Lone Pairs of Electrons on Molecule Geometry
02:27Predicting Molecular Geometry
VSEPR Theory for Determination of Electron Pair Geometries
02:42Ionic Crystal Structures
Ionic crystals consist of two or more different kinds of ions that usually have different sizes. The packing of these ions into a crystal structure is more complex than the packing of metal atoms that are the same size.
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
02:34Structural Isomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
01:19Structure of Amines
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’ carbon–carbon bond (154 pm). These aspects are illustrated in Figure...