Development of simultaneous measurements system of electric conductivity and x-ray diffraction on mantle minerals at high pressure and temperature

高压高温地幔矿物电导率和X射线衍射同步测量系统研制

基本信息

批准号：
15340187
负责人：
NAGAI Takaya
金额：
$ 9.98万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

A diamond anvil cell, which can apply to electric resistance and x-ray diffraction measurements simultaneously, was designed in this research project. The DAC is basically modified the lever & spring type DAC and two electrodes model for electric resistance measurements is installed the DAC.A series of single crystals of the magnetite (Fe_3O_4)-ulvospinel (Fe_2TiO_4) solid solution were synthesized by the FZ method. Then, electric resistance measurements were performed on those samples and x-ray diffraction measurements were also performed at the same time.Electric resistances on all samples decrease gradually with increasing pressure probably due to the electron hopping and the band overlapping mechanism. However, the electric resistances suddenly show no pressure-dependency-above some critical pressures. The critical pressure increases with iron content in the solid solution of Fe_<3-x>Ti_xO_4. For example, the critical pressures are about 6.5GPa for Fe_2TiO_4 and about 24GPa for Fe_3O_4. X-ray powder diffraction patterns obtained above the critical pressure showed that some single diffraction peaks split into doublet peaks above the critical pressure. The evidence suggests a structural transition occurs at the critical pressure. According to the single crystal structure analysis experiments on Fe_2TiO_4 at high pressure, the structural transition could be assigned as the transition from cubic to tetragonal symmetry and the Mn_3O_4 type structure can be proposed as a candidate of the high-pressure form of Fe_2TiO_4. The newly designed system in this research project can provide some interesting and important information about the relationship between the crystal structures and electric resistances.

本研究项目设计了一种可同时进行电阻和X射线衍射测量的金刚石砧池。该DAC在杠杆弹簧式DAC的基础上进行了改进，并在DAC上安装了用于电阻测量的两个电极模型。采用FZ法合成了一系列磁铁矿(Fe_3O_4)-硫尖晶石(Fe_2TiO_4)固溶体的单晶。然后，对这些样品进行电阻测量，同时还进行X射线衍射测量。所有样品的电阻随着压力的增加而逐渐减小，这可能是由于电子跳跃和能带重叠机制。然而，在高于某些临界压力时，电阻突然表现出不具有压力依赖性。临界压力随着Fe_<3-x>Ti_xO_4固溶体中铁含量的增加而增加。例如，Fe_2TiO_4的临界压力约为6.5GPa，Fe_3O_4的临界压力约为24GPa。在高于临界压力时获得的X射线粉末衍射图表明，在高于临界压力时一些单衍射峰分裂成双峰。有证据表明，在临界压力下会发生结构转变。根据高压下Fe_2TiO_4的单晶结构分析实验，可以将结构转变归结为立方对称向四方对称的转变，并提出Mn_3O_4型结构作为Fe_2TiO_4高压形态的候选结构。该研究项目中新设计的系统可以提供有关晶体结构与电阻之间关系的一些有趣且重要的信息。

项目成果

期刊论文数量（34）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Variation of hydrogen bonded O【triple bond】O distances in goethite at high pressure

针铁矿高压下氢键O【三键】O距离的变化

DOI：
发表时间：
2003
期刊：
American Mineralogist 88
影响因子：
0
作者：
W.Nakagawara et al.;Takaya Nagai
通讯作者：
Takaya Nagai

中性子と高圧のカップリングでなにが見えるか?

当中子和高压耦合时你能看到什么？

DOI：
发表时间：
2004
期刊：
高圧力の科学と技術 14
影响因子：
0
作者：
M.Sugiyama;M.Annaka;K.Hara;M.E.Vigild;G.E.Wignall;永井隆哉
通讯作者：
永井隆哉

Intense pursed neutron sources open a new window of mineralogy

强中子源打开矿物学新窗口

DOI：
发表时间：
2004
期刊：
Japanese Magazine of Mineralogical and Petrological Sciences 33
影响因子：
0
作者：
M.Annaka;M.Sugiyama;M.Kasai;T.Nakahira;T.Matsuura;H.Seki;T.Aoyagi;T.Okano;M.Miyazaki et al.;Takaya Nagai
通讯作者：
Takaya Nagai

中性子散乱実験と鉱物学の新展開

中子散射实验和矿物学新进展