高スピンコバルト (II) イオンが正方形平面調整:オキシ硫化物Sr2CoO2Cu2S2とBa2CoO2Cu2S2とその固体溶液の構造と磁気
Catherine F Smura1, Dinah R Parker, Mohamed Zbiri
1Department of Chemistry, University of Oxford, Oxford, UK.
Journal of the American Chemical Society
|February 10, 2011
まとめ
この研究は,層状のオキシカルコゲニドが反鉄磁性秩序を示すことを明らかにし,コバルト協調多面体の四角延伸により, Ba 含有量とともに秩序化された磁気モメントが増加する. この延長は,コバルト (II) イオンの中の消えない軌道成分を強化する.
科学分野:
- マテリアルサイエンス 材料科学
- 固体物理 固体物理学
- 無機化学 無機化学とは
背景:
- 層状のオキシカルコゲン化物 (Sr{1-x}Ba{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}{-x}) は,その磁性特性について研究されている.
- これらの化合物のコバルト (III) イオンは,酸化物と硫化物によって調整され,四角形の長方形の八面体を形成します.
研究 の 目的:
- 粉末中性子 difraktion を用いて (Sr(1-x) Ba(x))(2)CoO(2)Cu(2)S(2) の反鉄磁気構造を決定する.
- 構造的パラメータ,特に四角延伸とコバルト (II) イオンの磁気特性との相関を調査する.
主な方法:
- 粉末中性子 difrractionは,結晶と磁気構造を決定するために使用されました.
- 実験的観測を裏付けるために,Ab initio計算が行われました.
主要な成果:
- Antiferromagnetic orderingが観察され,近隣のコバルト (II) モモントがCoO (II) 平面内で反鉄磁気的に結合した.
- コバルト (II) のオーダーされた磁気モーメントは,Ba含有量とともに増加し,CoO (4S) (2) 多面体の四角延伸と相関する.
- 湿った空気の曝露によって引き起こされる銅欠乏は,オーダーされた磁気モメントの減少につながります.
結論:
- コバルトの協調環境の四角延長は,磁気特性,特に消えない軌道成分に大きな影響を与える.
- ネール温度以下で観測された磁力圧縮歪みは,オーダーされた磁気モメントの大きさと関連しています.
関連する概念動画
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
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...
02:34Structural 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...
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...
02:46Crystal 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,...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...