Structure analysis of pressure-induced amorphous state of a molecular crystal with tetrahedral molecules
| Project/Area Number |
12640309
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
|
|---|
| Research Institution | Ochanomizu University |
|---|
Principal Investigator |
HAMAYA Nozomu Ochanomizu Univ., Graduate School of Humanities and Sciences, Professor, 大学院・人間文化研究科, 教授 (70156420)
|
|---|
| Project Period (FY) |
2000 – 2001
|
| Project Status |
Completed (Fiscal Year 2001)
|
| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2001: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2000: ¥2,400,000 (Direct Cost: ¥2,400,000)
|
|---|
| Keywords | molecular solid / pressure-induced amorphization / pressure-induced molecular dissociation / amorphous structure analysis / amorphous-amorphous phase transition / synchrotron radiation / high-pressure x-ray diffraction / アモルファス間相転移 / 分子解離 / 圧力誘起アモルファス / 放射光X線回折実験 |
|---|
| Research Abstract |
The objective of the present work is to study a mechanism of amorphization process induced by pressure in SnI_4, a molecular crystal consisting of tetrahedral molecules. Major goals are to establish an experimental technique for determination of amorphous structure from synchrotron x-ray diffraction data collected at high pressure and to obtain detailed structural knowledge of metallic amorphous SnI_4 in a wide pressure range.
In the first fiscal year, we designed and constructed a new diamond anvil cell (DAC) device and prepared some instruments at BL04B2 at SPring-8 for the present study. Diffraction patterns of metallic amorphous SnI_4 at 35, 45 and 55 GPa were measured first. Elaborating an estimation of reliable scattering intensities, we finally obtained the structure factor S(Q) and the reduced radial distribution function G(r) at each pressure. Inspecting G(r) we found that the SnI4 molecules are no longer existent in the amorphous state between 35 and 55 GPa and that its G(r) shows many features of the amorphous structure formed by the dense random packing of hard spheres.
In the second fiscal year, various studies were conducted. Diffraction study of SnI_4, revealed that at 2.5 GPa on decompression there is an amorphous-amorphous phase transition accompanied by the re-formation of the SnI_4 molecules. Other studies include the recrystallization from the amorphous state at high temperature and high pressure, the amorphization under hydrostatic condition and the Mossbauer spectroscopy at high pressure utilizing the nuclear forward scattering. Examining thermodynamic stability of the amorphous state, its atomic-scale structure and its electronic structure, we now discuss the mechanism of the pressure-induced amorphization process in SnI_4.
Part of the results of this study were presented at the 18th AIRAPT International Conference (Beijin) in Aug., 2001 and the 11th International Conference on Liquid and Amorphous Metals (Yokohama) in Sep., 2001
|
Report
(3 results)
Research Products
(5 results)
