权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Study of the pressure-induced phase transition on molecular conductors from the X-ray diffraction measurement

通过 X 射线衍射测量研究压力诱导的分子导体相变

基本信息

批准号：
12640307
负责人：
YAMAURA Jun-ichi
金额：
$ 1.86万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640307/
关键词：
molecular conductor high-pressure X-ray diffraction one-dimensional electronic system

项目摘要

The intention of this research is to develop the high-pressure structural study for molecular conductors. The "easy handling" powder X-ray diffraction type diamond anvil cell was produced to study the high-pressure structure investigation.Molecular conductors Me_4X(CPDT-TCNQ)_2 (X=N, P, As) having the extremely one-dimensional electronic system show the metal-insulator transition at 135K (X=N), 165K (X=P) and 185K (X=As). The origin of the transition at low temperature is different with the displacement of the cation. For Me_4N, Me_4P, Me_4As compounds, the insulating states were also observed under pressure at room temperature. From the high-pressure X-ray difrraction measurement, I identified that the transitions under pressure are originated by the 2_kF CDW for Me_4N, Me_4P salts and 4k_FCDW for Me_4As salt. I succeeded to complete the universal pressure-temperature phase diagram for the series of the compounds. The present result is significant to the research for a variety of one-dimensional molecular conductors.One-dimensional π-d conductors (DBr-DCNQI)_2Cu and (DI-DCNQI)_2Cu show drastic changes in the conducting properties depending on the electronic state of Cu atoms. The detail investigation of the lattice parameter clarifies the sight difference of their structures in the high-pressure anomalous metallic phases. This structural character is the origin of the appearance of the different high-pressure metallic state for the both compounds. This result would contribute the development of the research for the DCNQI system having the unique electronic and magnetic properties under pressure.

本研究旨在开展分子导体的高压结构研究。为了研究高压结构，制作了“易操作”粉末X射线衍射型金刚石压腔。具有极一维电子体系的分子导体Me_4X(CPDT-TCNQ)_2(X=N，P，As)在135K(X=N)，165K(X=P)和185K(X=As)表现出金属-绝缘体的转变。低温相变的起因与阳离子的位移不同。对于Me_4N、Me_4P、Me_4As化合物，在室温压力下也观察到了绝缘态。通过高压X射线衍射测量，确定了Me_4N、Me_4P盐和Me_4As盐的2KF-CDW和Me_4As-4K_FCDW在压强下的相变。我成功地完成了该系列化合物的通用压力-温度相图。这一结果对各种一维分子导体的研究具有重要意义。一维π-d导体(DBr-DCNQI)_2Cu和(DI-DCNQI)_2Cu的导电性质随铜原子电子态的不同而发生显著变化。通过对晶格参数的详细研究，阐明了它们在高压反常金属相中的结构视差。这种结构特征是这两种化合物出现不同高压金属状态的原因。这一结果将有助于DCNQI体系在压力下具有独特的电磁性能的研究的发展。