Mechanism of pressure-induced amorphization, superconductivity and molecular dissociation in tetrahedral-molecular crystals

四面体分子晶体中压力诱导的非晶化、超导和分子解离机制

• 批准号: 10440089
• 负责人: HAMAYA Nozomu
• 金额: $ 8.64万
• 依托单位: Ochanomizu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10440089/
• 关键词: molecular crystal; pressure-induced amorphozation; pressure-induced molecular dissociation; low-temperature high-pressure x-ray diffraction measurement; multiple extreme condition; synchrotron radiation experiment; pressure-induced superconductivity

The objective of the present work is to study structural properties of tetrahedral-molecular crystals SnIィイD24ィエD2 and SnBrィイD24ィエD2 at low temperature and at ultrahigh pressure. Major goals are (1) to determine crystal structure of the nonmolecular phase of SnIィイD24ィエD2 crystallizing from the amorphous phase at 60 Gpa at room temperature and (2) to establish a P-T phase diagram down to 10K and up to 100 Gpa. In the first fiscal year, we designed and constructed two pieces of apparatus crucial for those experiments. One is a low-temperature cryostat equipped with a diamond anvil cell (DAC) device for high-pressure generation. Another is a spectrometer capable of measuring fluorescence from ruby micro-chips encapsulated in a sample chamber in a DAC. Duplicates of them were later installed at the BL10XU station at the SPring-8 synchrotron radiation experimental facility.In the second fiscal year, we carried out synchrotron x-ray diffraction experiments at the SPring-8, using the apparatu … More s described above. A low temperature condition of 18K and a high pressure condition of 89 GPa were reached simultaneously. The following results were obtained:(1) The nonmolecular phase of SnIィイD24ィエD2 has the same crystal structure as a substitutional, disordered alloy with the fcc lattice. The lattice sites are occupied by the Sn and I atoms at random.(2)At 18K, the amorphous phase persists to a very high pressure of 80 Gpa, suggesting that a thermal activation process plays an important role in the amorphous-nonmolecular phase transition. No new crystal structures were observed in this study. Results of previous Mossbauer studies at low temperature and high pressure need to be reexamined on the basis of the phase relationship determined in the present study.(3) A new crystal structure of SnBrィイD24ィエD2 stable between 3 Gpa and 9 Gpa was determined to be cubic. Effect of pressure on disordering of crystal structure is much more insensitive in SnBrィイD24ィエD2 than in SnIィイD24ィエD2.The results of this study were presented at the IUCr Congress and General Assembly (Glasgow), the fall meeting of the Physical Society of Japan (Morioka), and the annual meeting of the Japan Society of High Pressure Science and Technology (Fukuoka) in 1999. Less

本工作的目的是研究低温和超高压条件下四面体分子晶体SnI φ φ D24 φ φ D2和SnBr φ φ D24 φ φ D2的结构性质。主要目标是(1)确定在室温下由非晶相在60 Gpa下结晶的SnI φ D24 φ D2的非分子相的晶体结构；(2)建立低至10K和高至100 Gpa的P-T相图。在第一个财政年度，我们设计并建造了两个对这些实验至关重要的设备。一种是低温恒温器，配有金刚石砧细胞（DAC）装置，用于高压产生。另一种是能够测量封装在DAC样品室中的红宝石微芯片的荧光的光谱仪。它们的复制品后来被安装在BL10XU站的SPring-8同步辐射实验设施上。在第二个财政年度，我们在SPring-8上进行了同步加速器x射线衍射实验，使用的设备如上所述。同时达到了18K的低温条件和89 GPa的高压条件。得到以下结果：(1)SnI φ φ D24 φ φ D2的非分子相具有与fcc晶格取代无序合金相同的晶体结构。晶格位置被Sn和I原子随机占据。(2)在18K时，非晶相持续到80gpa的高压，表明热活化过程在非晶-非分子相变中起重要作用。本研究未发现新的晶体结构。以往在低温高压下的穆斯堡尔研究结果需要在本研究确定的相关系的基础上重新检验。(3)确定了一种稳定在3 ~ 9 Gpa范围内的新型SnBr的立方晶体结构。在SnBr中，压力对晶体结构无序性的影响比在SnI中不敏感。该研究结果于1999年在IUCr大会和大会（格拉斯哥）、日本物理学会秋季会议（森冈）和日本高压科学技术学会年会上（福冈）发表。少

项目成果

浜谷 望: "8Gev光(BL10XU)をつかう超高圧力下の物性研究"日本結晶学会誌. 42(印刷中). (2000)

Nozomi Hamatani：“使用 8Gev 光 (BL10XU) 进行超高压物理性质的研究”，日本晶体学会杂志 42（出版中）。

N. Hamaya and K. Sato: "Phase transition in AXィイD24ィエD2 type molecular crystals under pressure"Acta Crystallog. A55(Supplement). 83 (1999)

N. Hamaya 和 K. Sato：“AXIID24D2 型分子晶体在压力下的相变”Acta Crystallog A55（增刊）。

K.Sato: "Structure analysis of non-molecular phase of SnI_4 using anomalous scattering at high pressure"Acta Crystallog. (Supplement). A55. 553 (1999)

K.Sato：“使用高压异常散射对 SnI_4 非分子相进行结构分析”Acta Crystallog。

浜谷 望: "DACを用いた多結晶X線回折実験"高圧力の科学と技術. 9. 263-269 (1999)

Nozomu Hamatani：“使用 DAC 的多晶 X 射线衍射实验”高压科学与技术。9. 263-269 (1999)。

N. Takeshita, S. Kometani, M. Eremets, K. Shimizu, K. Amaya, and N. Hamaya: "Pressure induced superconductivity of SnlィイD24ィエD2"in The Review of High Pressure Science and Technology, vol. 7 edited by M. Nakahara (Jpn. Soc. in High Press. Sci. Technol., Ky

N. Takeshita、S. Kometani、M. Eremets、K. Shimizu、K. Amaya 和 N. Hamaya：“SnlD24D2 的压力诱导超导性”，《高压科学与技术评论》，第 7 卷，M. Nakahara 编辑。 （Jpn. Soc. in High Press. Sci. Technol.，Ky