压力诱导的相变和中性基导体导体的金属化
Joanne W L Wong1, Aaron Mailman, Kristina Lekin
1Department of Chemistry, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada.
Journal of the American Chemical Society
|January 10, 2014
概括
压力将氧桥接的1,2,3-bisdithiazolyl基导体3a从莫特绝缘体转变为金属. 这一阶段过渡涉及结构变化和导电性的显著增加.
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
- 晶体学 晶体学是指结晶学.
- 有机电子 有机电子
背景情况:
- 氧桥接的1,2,3-bisdithiazolyl基导体3a表现出压力依赖的特性.
- 了解激光导体中的相变对于开发新型电子材料至关重要.
研究的目的:
- 在变压下研究基导体3a的晶体结构和电荷传输特性.
- 阐明压力诱导相变的机制和金属状态的形成.
主要方法:
- 高压X射线衍射以确定晶体结构 (α,β和γ相).
- 在不同压力和温度下测量电导率.
- 高压红外吸收和反射光谱学.
- 密度函数理论 (DFT) 计算用于电子结构分析.
主要成果:
- 压缩会诱导从α相 (Fdd2) 到β相 (Pbn21) 的相位过渡,大约在3-4 GPa,然后在8 GPa时再到γ相 (Pbn21).
- 结构性变化涉及"铁"的卷曲的带,导致更平面的激进安排.
- 电导率在压力超过4GPa时增加3个数量级,并伴随着激活能量降至零.
- 接近4-5GPa的Mott-Hubbard差距关闭表明过渡到金属状态.
结论:
- 根导体3a在相对较低的施加压力下很容易过渡到金属状态.
- 低的LUMO和3a的高电子亲和度有助于其电子柔软性和低库伦电位 (U).
- 在压力下的晶体轨道混合 (SOMO/LUMO) 促进了金属状态的形成.
相关概念视频
Phase Transitions
19.1K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
19.1K
Phase Transitions
108
A phase transition is the process in which a substance changes from one state of matter to another, like from a solid to a liquid, liquid to gas, or vice versa, at a specific temperature and under given pressure conditions. This change is spontaneous and is affected by alterations in temperature and pressure. These parameters impact the strength of the forces between molecules (intermolecular forces) in the substance.During a phase transition, both the initial and final phases of the substance...
108
Radical Reactivity: Overview
2.2K
Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired...
2.2K
Metal-Semiconductor Junctions
1.4K
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...
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...
1.4K
Phase Changes
3.7K
Phase transitions play an important theoretical and practical role in the study of heat flow. In melting or fusion, a solid turns into a liquid; the opposite process is freezing. In evaporation, a liquid turns into a gas; the opposite process is condensation.
A substance melts or freezes at a temperature called its melting point and boils or condenses at its boiling point. These temperatures depend on pressure. High pressure favors the denser form of the substance, so typically, high pressure...
A substance melts or freezes at a temperature called its melting point and boils or condenses at its boiling point. These temperatures depend on pressure. High pressure favors the denser form of the substance, so typically, high pressure...
3.7K
Radical Formation: Overview
1.9K
A bond can be broken either by heterolytic bond cleavage to form ions or homolytic bond cleavage to yield radicals. A fishhook arrow is used to represent the motion of a single electron in homolytic bond cleavage. There are two main sources from which radicals can be formed:
Radicals from spin-paired molecules:
Radicals can be obtained from spin-paired molecules either by homolysis or electron transfer. While two radicals are formed in the former, an electron is added in the...
Radicals from spin-paired molecules:
Radicals can be obtained from spin-paired molecules either by homolysis or electron transfer. While two radicals are formed in the former, an electron is added in the...
1.9K


