BaCuO2+xにおける鉄磁性Cu6とCu18のクラスターの反鉄磁性オーダーリングとパラ磁性行動
Science (New York, N.Y.)
|April 15, 1994
まとめ
磁気化と中性子 difraktionは,BaCuO2+xの磁気的振る舞いを明らかにしています. 銅6のリングクラスターは反鉄磁性秩序を示し,銅18の球体クラスターはパラ磁性であり,量子効果は最小限に留まります.
科学分野:
- 凝縮物質物理学 凝縮物質物理学
- マテリアルサイエンス 材料科学
- マグネチズム (磁気) とは
背景:
- バリウム銅酸化物 (BaCuO2+x) は,磁気における潜在的な応用を持つ複雑な酸化物です.
- 構成クラスターの磁気特性を理解することは,材料設計において極めて重要です.
研究 の 目的:
- 磁気化と中性子 difraktion を用いて BaCuO2+x の磁気的振る舞いを調査する.
- Cu(6) リングとCu(18) 球団の磁気順序を特徴づけるために.
主な方法:
- ポリクリスタリン BaCuO2+x のサンプルを磁気化測定にかけました.
- 磁気構造と秩序を調査するために,中性子 difraktion が採用されました.
主要な成果:
- Cu(6) のリングクラスターは,大きなスピンと15K以下で反鉄磁的にオーダーされた鉄磁性基底状態を示します.
- Cu(18) 球団は鉄磁性基底状態を有しているが,2Kまでパラマグネティックのままである.
- Cu(6) リングのオーダーモメントはCuあたり0.89(5) ボール磁トンで,これは小さな量子変動効果を示している.
結論:
- BaCuO2+xは,その独特なクラスター構造によって誘発される磁気行動の組み合わせを示しています.
- Cu(6) の環は強固な反鉄磁性秩序を示し,Cu(18) の球は低温で秩序が低い.
- 予測モデルは,1K未満のCu(18) クラスタのフェロマグネティック・インタークラスター・オーダーを示唆している.
さらに関連する動画
12:05Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia
Published on: October 10, 2013
08:55Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
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...
02:58Crystal 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...
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...
02:33Lattice Centering and Coordination Number
The structure of a crystalline solid, whether a metal or not, is best described by considering its simplest repeating unit, which is referred to as its unit cell. The unit cell consists of lattice points that represent the locations of atoms or ions. The entire structure then consists of this unit cell repeating in three dimensions. The three different types of unit cells present in the cubic lattice are illustrated in Figure 1.
Types of Unit Cells
Imagine taking a large number of identical...
Types of Unit Cells
Imagine taking a large number of identical...
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...