Crystal structure refinement of mantle minerals under high pressure and temperature using Rietveld method

Rietveld法高温高压下地幔矿物晶体结构细化

基本信息

批准号：
13440162
负责人：
NAGAI Takaya
金额：
$ 9.22万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13440162/
关键词：
laser annealing high pressure high temperature mantle minerals structure refinement Rietveld method diamond anvil cell

项目摘要

In-situ X-ray diffraction measurements under pressure were performed on several minerals and obtained powder diffraction patterns were analyzed by means of Rietveld structure refinement method. High pressure is generated by a diamond anvil cell (DAC) and X-ray diffraction experiments were mainly performed in synchrotron radiation facilities, such as PF and SPring8.Shortening of hydrogen bonded oxygen-oxygen distances controls compression of some hydrous minerals, such as KHCO_3 and NaHCO_3. A phase transition occurs on KHCO_3 at about 2.8 Gpa. It is interesting thai hydrogen bonded O-O distance in NaHCO_3 reaches to 2.4 A^^○ at 9 Gpa and this suggests a possibility of hydrogen bond symmetrization. Shortening of hydrogen bonded O-O distance also controls compression behavior of goethite and its shortening behavior is quite similar to that of ice VII.Laser annealing is quile useful for relaxing strain in materials caused by nonhydrostatic pressure Laser annealing was applied to compression experiments of NiTiO_3-ilmenite in PF. Obtained diffraction patterns after annealing treatment were greatly improved and Rietveld analysis could be done successfully up to 20 Gpa.Laser heating is a powerful method for creating lower mantle conditions on the earth. We performed insitu X-ray diffraction experiments under high pressure and temperature conditions at SPnng8 to clarify a possibility of a reaction between maguesite and iron. No evidence of the reaction was observed at 2000℃ and 1000℃ at 40 Gpa Diffraction patterns of CaSiO_3 perovskite could be observed at 20 Gpa and 1500-1600 K. Technical improvements are still needed but quite good quality diffraction patterns were recorded.EOS of CaO was determined by X-ray diffraction measurements using a hydraulically operated DAC and discusses a possibility of dissociation reaction of CaSiO_3 perovskile at the lowest part of the lower mantle.

对几种矿物进行了压力下的原位X射线衍射测量，并通过Rietveld结构细化方法对通过金刚石砧室（DAC）产生的高压进行了粉末衍射图谱分析，并主要进行了X射线衍射实验。在同步加速器辐射设施中进行，例如 PF 和 SPring8。氢键氧-氧距离的缩短控制了一些含水矿物的压缩，例如 KHCO_3 和NaHCO_3 在约 2.8 Gpa 时发生相变，有趣的是 NaHCO_3 中的氢键 O-O 距离在 9 Gpa 时达到 2.4 A^^○，这表明氢键 O-O 距离也可能缩短。控制针铁矿的压缩行为，其缩短行为与冰非常相似 VII. 激光退火对于松弛应变非常有用将激光退火应用于PF中NiTiO_3-钛铁矿的压缩实验，退火处理后获得的衍射图样得到改善，并且可以在高达20 Gpa的压力下成功完成Rietveld分析。激光加热是产生较低压力的有力方法。我们在 SPnng8 的高压和高温条件下进行了原位 X 射线衍射实验，以阐明菱镁矿与地幔之间发生反应的可能性。在 2000℃ 和 1000℃、40 Gpa 下没有观察到反应的证据。在 20 Gpa 和 1500-1600 K 下可以观察到 CaSiO_3 钙钛矿的衍射图。仍需要技术改进，但记录了相当好的质量衍射图。EOS CaO 的测定是通过使用液压操作 DAC 的 X 射线衍射测量来确定的，并讨论了离解反应的可能性CaSiO_3钙钛矿位于下地幔的最低部分。