一维过渡金属-三明治聚合物:可能是旋转运输的理想导体
Hongjun Xiang1, Jinlong Yang, J G Hou
1Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
Journal of the American Chemical Society
|February 16, 2006
概括
我们探索了一维的过渡金属聚合物,发现V (Bz) 和Mn (Bz) 具有有希望的磁性. 拉伸这些聚合物显著改变了它们的电子和磁性行为,提供了可调节的功能.
科学领域:
- 材料科学 材料科学 材料科学
- 凝聚物质物理学 凝聚物质物理学
- 计算化学计算化学
背景情况:
- 一维 (1D) 协调聚合物具有独特的电子和磁性.
- 过渡金属-三明治结构对新型材料设计有兴趣.
研究的目的:
- 研究1D过渡金属聚合物的电子和磁性.
- 探索结构修改 (如拉伸) 对这些属性的影响.
- 评估在有限温度下铁磁排序的潜力.
主要方法:
- 使用密度函数理论 (DFT) 的计算.
- 分析了电子带结构和磁性特性.
- 模拟了拉伸应变对聚合物特性的影响.
主要成果:
- [V(Bz) ]无限展现了近乎半金属的铁磁性.
- [Mn(Bz) ]无限被预测为一个半金属铁磁铁.
- 拉伸[V(Bz) ]无限诱导半金属行为,而拉伸[Mn(Bz) ]无限成为反铁磁绝缘体.
结论:
- 通过变形TM-Bz聚合物,可以获得可调节的电子和磁性质.
- 在有限的温度下,可以稳定[V(Bz]无限度和[Mn(Bz]无限度中的铁磁顺序.
- 这些聚合物的六角束可以通过链间合表现链内铁磁秩序.
相关概念视频
Metallic 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...
Properties of Transition Metals
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.
Stereoisomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Valence 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...
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The contact of metal and semiconductor can lead to the formation of a junction with either Schottky or Ohmic behavior.
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
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Biasing metal-semiconductor junctions involves applying a voltage across the junction. Specifically, the metal is connected to a voltage source, while the semiconductor is grounded. This technique is essential for controlling the direction and magnitude of current flow in electronic devices, including diodes, transistors, and photovoltaic cells.
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
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