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四面体分子晶体SNII D24IE D2和SNBRII D24IE D2在低温和超高压力下的结构特性。主要目标是（1）确定SNII D24IE D2非分子相的晶体结构，在室温下60 GPA和（2）下从无定形相结晶，以建立P-T相图至10K，最高为100 GPA。第一个会计年度，我们设计并构建了对于这些实验至关重要的两个设备。一种是配备有钻石砧台（DAC）装置的低温低温恒温器，可用于高压生成。另一个是光谱仪，能够测量封装在DAC样品室内的红宝石微芯片的荧光。它们的重复项随后在弹簧-8同步辐射实验设施的BL10XU站安装。在第二会计年度中，我们使用Apperatu…使用Apperatu…在Spring-8上进行了同步X射线衍射实验。简单地达到了18K的低温条件和89 GPA的高压条件。获得了以下结果：（1）SNII D24 D2的非分子相具有与替代性，无序合金与FCC晶格相同的晶体结构。晶格位点由SN和I原子随机占据。（2）在18K时，无定形相持续到非常高的80 GPa压力，这表明热激活过程在非物体非分子相变中起重要作用。在这项研究中未观察到新的晶体结构。在本研究中确定的相位关系的基础上，需要在低温和高压下进行的摩斯鲍尔研究的结果重新检查。（3）SNBRII D24IE D2稳定的新晶体结构在3 GPA和9 GPA之间被确定为立方体。与SNII D24IE D2相比，SNBRII D24IE D2压力对晶体结构的无序的影响更加不敏感。这项研究的结果是在IUCR国会和大会和大会（Glasgow）（日本物理学会（Morioka）的秋季会议（Morioka）的秋季会议上提出的，以及高压科学和较高的高压科学技术的年度会议（Fukuoka）。

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）。

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。

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）。

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