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

Structural phase transformation of inorganic compounds under very high pressure studied by in-situ X-ray diffraction analysis

原位 X 射线衍射分析研究超高压下无机化合物的结构相变

基本信息

批准号：
02403028
负责人：
SYONO Yasuhiko
金额：
$ 15.04万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

An X-ray diffraction system has been combined with a 250 ton cubic-anvil type high pressure apparatus to make in-situ measurements of crystal structure, compressibility and phase equilibrium of pressure-induced phases of inorganic substance. The X-ray diffraction system consists of intense X-ray source of the rotating anode type (6OkV, 200mA), and solid state detector and pulse height analyzer system (2048 channels, 2627eV/channel). Both the X-ray source and goniometer carrying SSD are mounted on a common plate so as to make easier adjustment of optical path through pressure-medium composed of boron-epoxy lesin mixture. The d-specings of the diffraction peaks of NaCl which is used for pressure standard could be determined with an accuracy of <plus-minus> 0.1 %, which in turn warrants precision of (SY.+-.[) 0.1 GPa for the pressure calibration. B1-B2 transition of KCl was also detected at 2.1 GPa with a volume decrease of 13 %, in agreement with previous reports. Bulk moduli of B1 and B2 phase of KCl were also determined to be 18.2 <plus-minus> 0.2 and 21.5 <plus-minus> 1.1 GPa, respectively. Pressure-induced phase transition of SrF_2 was also studied up to 8GPa at room temperature. Fluorite structure was observed up to 5.8 GPa, where transformation to a PbCl_2 type took place. However, the high pressure phase remained down to 2.0 GPa with decreasing pressure, indicating a remarkable hysteresis. These observations suggest a martensitic mechanism of the fluorite-PbCl_2 type phase transition, which has been noted to be very sensitive to hydrostacity due to pressure medium. Bulk modili of SrF_2 with the fruorite and PbCl_2 type were determined to be 69.1 <plus-minus> 0.7 and 73.6 <plus-minus> 3.8 GPa respectively, in agreement with previous data. Along with the construction of insitu diffraction system, various investigations of phase transition in MO_2 and M_2O_3 were carried out at high pressure and temperatures, and crystallochemical implications were discussed.

X射线衍射系统与250吨立方砧式高压装置相结合，对无机物的晶体结构、压缩性和压力诱导相的相平衡进行了原位测量。 X射线衍射系统由旋转阳极型强X射线源（6OkV，200mA）、固态探测器和脉冲高度分析系统（2048通道，2627eV/通道）组成。 X射线源和带有SSD的测角仪都安装在一个公共板上，以便通过硼环氧树脂混合物组成的压力介质更容易地调整光路。用于压力标准的 NaCl 衍射峰的 d 规格可以以 <正负> 0.1 % 的精度确定，这又保证了压力校准的 (SY.+-.[) 0.1 GPa 精度。在 2.1 GPa 下也检测到 KCl 的 B1-B2 转变，体积减少了 13%，与之前的报道一致。 KCl B1 和 B2 相的体积模量也分别确定为 18.2 <正负> 0.2 和 21.5 <正负> 1.1 GPa。还研究了室温下高达 8GPa 的压力引起的 SrF_2 相变。在高达 5.8 GPa 的压力下观察到萤石结构，并发生向 PbCl_2 型的转变。然而，随着压力的降低，高压阶段仍保持在2.0 GPa，表明存在显着的滞后现象。这些观察结果表明萤石-PbCl_2 型相变的马氏体机制，人们注意到该机制对压力介质造成的静水性非常敏感。果石型和 PbCl_2 型 SrF_2 的体积模量分别为 69.1 <正负> 0.7 和 73.6 <正负> 3.8 GPa，与之前的数据一致。随着原位衍射系统的构建，对MO_2和M_2O_3在高压和高温下的相变进行了各种研究，并讨论了晶体化学意义。