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Structure and Dynamics on Metal-Nonmetal transition in Ionic Liquids

离子液体中金属-非金属转变的结构和动力学

基本信息

批准号：
04640348
负责人：
TAKEDA Shin'ichi
金额：
$ 1.15万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

The ultrasonic velocity, sound attenuation and density measurements have been carried out for molten Cu(Cl_<1-x>Br_x) mixtures to investigate the thermodynamic and dynamical properties. The adiabatic compressibility of this system was obtained from the observed ultrasonic velocity and density. The observed compressibility has the maximum value around Cu(Cl_<0.2>Br_<0.8>), which suggests large fluctuaion in the molten salt mixtures. The sound attenuation shows large temperature dependence around the same composition.EXAFS measurement for molten CuX(X=Cl, Br) and agX(X=Cl, I) has been carried out near the melting temperature to study the partial structure. The obtained Cu-halogen and Ag-halogen distances are about 0.1A-0.2A shorter than the distances obtained from neutron deffraction measurement by isotopic substitution method and the results suggest the cluster formation such as a CuX(X=Cl, Br) and AgX(X=Cl, I) trimmer in the liquid state.Neutron diffraction, ultrasonic velocity and den … More sity measurements have been carried out for liquid Bi-Ga alloys along the liquidus curve and at temperatures above the critical point where the miscibility gap closes. A remarkable change in the structure factor has been observed at the critical concentration, and the temperature coefficient of the adiabatic compressibility shows rather small value above the miscibility gap region. This suggests that the spatial fluctuation due to the thermal agitation does not affect the compressibility in the miscibility gap region, and the atoms can easily be rearranged to have the preferable structure with smaller spatial fluctuations.The structure factors of liquid Te at 470C and 570C have been measured by X-ray and neutron diffraction. The ion-electron correlation function and valence electron distribution were evaluated from this difference at the two temperatures. The obtained charge distribution function shows two peaks at the distance around 0.8A and 1.7A just above the melting temperature. Those correspond to the distribution of the lone pair electrons and the covalent bonded electrons around a central tellurium ion, respectively. At 570C, single peak is observed at the distance around 1.1A in the electron charge distribution. This corresponds to the change of the local charge density distribution from non-metalllic state to metallic one in liquid Te. Less

对熔融Cu(Cl_<1-x>Br_x)混合物进行了超声速度、声衰减和密度测量，以研究其热力学和动力学性质。该系统的绝热压缩性是通过观察到的超声速度和密度获得的。观察到的压缩率在Cu(Cl_<0.2>Br_<0.8>)附近具有最大值，这表明熔盐混合物存在较大的波动。声音衰减在相同成分周围表现出很大的温度依赖性。在熔化温度附近对熔融的 CuX(X=Cl, Br) 和 agX(X=Cl, I) 进行了 EXAFS 测量，以研究部分结构。获得的Cu-卤素和Ag-卤素距离比同位素替代法中子衍射测量获得的距离短约0.1A-0.2A，结果表明在液态下形成了CuX(X=Cl, Br)和AgX(X=Cl, I)微调器等团簇。进行了中子衍射、超声速度和密度测量。对于液态 Bi-Ga 合金，沿着液相线曲线以及在高于混溶间隙闭合的临界点的温度下。在临界浓度下观察到结构因子的显着变化，并且绝热压缩系数的温度系数在混溶间隙区域上方显示出相当小的值。这表明热搅拌引起的空间涨落并不影响混溶间隙区域的压缩性，并且原子可以很容易地重新排列以具有较小空间涨落的优选结构。通过X射线和中子衍射测量了470℃和570℃液态Te的结构因子。根据两个温度下的差异来评估离子-电子相关函数和价电子分布。获得的电荷分布函数在熔化温度上方 0.8A 和 1.7A 左右的距离处显示出两个峰值。这些分别对应于中心碲离子周围的孤对电子和共价键电子的分布。在570℃时，在电子电荷分布中在1.1A附近的距离处观察到单峰。这对应于液态Te中局部电荷密度分布从非金属态到金属态的变化。较少的