ACo2As2 (A = EuとCa) の物理的または化学的圧力による局所から強く相関する電子の行動と混合ヴァレンスの移行
Xiaoyan Tan1, Gilberto Fabbris2,3, Daniel Haskel2
1Department of Chemistry and Biochemistry, Florida State University , Tallahassee, Florida 32306, United States.
Journal of the American Chemical Society
|February 4, 2016
まとめ
ACo2As2材料 (A = Eu, Ca) に圧力または化学的変化を加えると,反鉄磁石は鉄磁石に変換されます. 電子陽性A部位における微小な電子変化がコバルトを大幅に変化させる.
科学分野:
- 凝縮物質物理学
- 材料科学
- 固体化学
背景:
- 反鉄磁性材料は複雑な磁気行動を表すことができます.
- 電子と構造の特性を調整することは 磁気を制御する鍵です
研究 の 目的:
- ACo2As2化合物の反鉄磁性から鉄磁性への移行を調査する.
- 圧力,化学的圧縮,および磁気特性に対するアリオヴァレンスの置換の役割を理解する.
主な方法:
- EuCo2As2に関する高圧 (HP) 研究
- CaCo2As2をEuまたはLaで代用する.
- 電子構造の変化の分析,特にフェルミレベルでの状態の3D密度.
主要な成果:
- 物理的圧力,化学的圧縮,またはアリオヴァレンスの置換により,ACo2As2 (A = Eu, Ca) の鉄磁性への移行が誘発される.
- 電子陽性 A 部位における混合バレンスの状態は,フェルミレベルでの状態の Co 3d 密度を増加させる.
- 3d軌道群のわずかな変化 (<0.15電子) は磁気行動を劇的に変化させ,放大された電子効果を示します.
結論:
- 微小な電子の乱れは,強く相関する電子システムの磁性特性の重要な変化につながります.
- EuCo2As2の混合バレンスは圧力下では安定している.
- CaCo2As2の鉄磁気順序化は,化学的置換によって達成できる.
さらに関連する動画
関連する概念動画
02:58Properties of Transition Metals
30.7K
Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3–12 are transition elements. The f-block elements, also called inner transition metals (the lanthanides and actinides), also meet this criterion because the d orbital is partially occupied before the f orbitals.
30.7K
02:58Crystal Field Theory - Octahedral Complexes
31.7K
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...
31.7K
02:46Electron Configurations
28.3K
Electron configurations and orbital diagrams can be determined by applying the Aufbau principle (each added electron occupies the subshell of lowest energy available), Pauli exclusion principle (no two electrons can have the same set of four quantum numbers), and Hund’s rule of maximum multiplicity (whenever possible, electrons retain unpaired spins in degenerate orbitals).
The relative energies of the subshells determine the order in which atomic orbitals are filled (1s, 2s, 2p, 3s, 3p,...
The relative energies of the subshells determine the order in which atomic orbitals are filled (1s, 2s, 2p, 3s, 3p,...
28.3K
02:54Trends in Lattice Energy: Ion Size and Charge
27.2K
An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure of the strength of this attraction. The lattice energy (ΔHlattice) of an ionic compound is defined as the energy required to separate one mole of the solid into its component gaseous ions. For the ionic solid sodium chloride, the lattice energy is the enthalpy change of the process:
27.2K
02:37Metallic Solids
21.3K
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....
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability....
21.3K
03:26Electron Configuration of Multielectron Atoms
67.8K
The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the 3s orbital, giving a 1s22s22p63s1 configuration. The electrons occupying the outermost shell orbital(s) (highest value of n) are called valence electrons, and those occupying the inner shell orbitals are called core electrons. Since the core electron shells correspond to noble gas electron configurations, we can abbreviate electron...
67.8K