[NH4][Zn(HCOO) 3の金属形式の枠組みにおける乱雑・秩序のフェロ電気的移行
Guan-Cheng Xu1, Xiao-Ming Ma, Li Zhang
1Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China.
Journal of the American Chemical Society
|June 30, 2010
まとめ
新しい金属形式のフレームワークは,切り替え可能なパラ電気 - 鉄電気の相変化を示しています. この移行は,191 Kの3次元キラル構造内のアンモニアイオンの配列によって引き起こされる.
科学分野:
- マテリアルサイエンス 材料科学
- 固体化学 固体化学
- クリスタルグラフィーです.
背景:
- メタル・オーガニック・フレームワーク (MOF) は,様々な用途に合わせて調整可能な特性を提供しています.
- チラルのMOFは,エナチオセレクティブプロセスと新しい物理現象に関心があります.
- アンモニアイチオンは,フレームワーク材料の構造的移行に影響を与えることができます.
研究 の 目的:
- 三次元キラル金属フォーマットフレームワーク [NH(4) ][Zn(HCOO) ((3) ]の相変遷行動を調査する.
- 移行を誘発するアンモニアムカチオンダイナミクスの役割を理解する.
- 構造変化から生じる鉄電性体を特徴づける.
主な方法:
- 単結晶X線微分法で結晶構造を決定する.
- 熱分析のための微分スキャニング熱計 (DSC).
- 消電スペクトロスコーピーは,鉄電性の性質を調査する.
主要な成果:
- 化合物[NH(4) ][Zn(HCOO) ((3) ]は191Kで相変化を示している.
- この移行は,アンモニア (NH(4) ((+)) カチオンの乱れ-秩序の再配置と関連しています.
- 準電気-鉄電気の移行の証拠が観察され,カチオン配列に関連していました.
結論:
- 金属形式のフレームワークは,温度によって誘発されたパラ電気-鉄電気相転換を示しています.
- この材料における鉄電性を駆動する鍵となるメカニズムは,アンモニアカチオン配列です.
- この研究は,切替可能な電子特性のキラルフレームワーク化合物の可能性を強調しています.
関連する概念動画
02:37Metallic Solids
Metallic solids such as crystals of copper, aluminum, and iron are formed by metal atoms. The structure of metallic crystals is often described as a uniform distribution of atomic nuclei within a “sea” of delocalized electrons. The atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties.
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
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...
01:31Ferromagnetism
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
01:29Imperfections in Crystal Structure: Non-Stoichiometric Defects
Non-stoichiometric defects refer to a type of defect in the crystal structure of a compound where the ratio of its constituent elements deviates from the ideal stoichiometric ratio. There are two main types of non-stoichiometric defects: metal excess defects and metal deficiency defects.Metal excess defects occur when there is a slight surplus of metal ions than what is required by the stoichiometric ratio of the compound. For example, heating a sodium chloride crystal in sodium vapor results...