The compression and polymorphic phase transitions of iodine have been studied by using x-ray diffraction with a diamond anvil cell at high pressure up to 77GPa.Considering that iodine is reactive with iron in air,a co...The compression and polymorphic phase transitions of iodine have been studied by using x-ray diffraction with a diamond anvil cell at high pressure up to 77GPa.Considering that iodine is reactive with iron in air,a corrosion-resisting and high-strength gasket was put between the diamonds,thus the sample can be mounted at atmospheric pressure and room temperature.Pressure was measured in terms of the ruby fluorescence and the molybdenum diffraction as an internal pressure standard.According to the x-ray diffraction results,the iodine undergoes the following three structural phase transitions with pressure increasing:(1)At 21 GPa,from base centred orthorhombic phase(phase Ⅰ)to body centred orthorhombic phase(phase Ⅱ).A 2%change in volume occurs.(2)At 44 GPa,from phase II to body centred tetragonal phase(phase Ⅲ).This is a second order phase transition.(3)At 71 GPa,from phase III to fcc phase(phase Ⅳ).The volume decreases by 3%.At this time,the volume is 45%of the original one at atmospheric pressure.展开更多
Based on in situ high pressure x-ray diffraction with diamond anvil cell by using synchrotron radiation and pressure-quench x-ray measurement,phase transition of C_(60)under high pressured is studied.The maximum press...Based on in situ high pressure x-ray diffraction with diamond anvil cell by using synchrotron radiation and pressure-quench x-ray measurement,phase transition of C_(60)under high pressured is studied.The maximum pressure used is 30GPa in quasi-hydrostatic case but 44GPa in nonhydrostatic case.At ambient pressure,C_(60)crystal is a fcc phase with lattice parameter a=14.2086Å.It transforms from fcc to a lower symmetry phase at pressure of 13.7GPa,and then transforms to an amorphous state under pressure up to 25-30 GPa.This amorphous state is metastable at normal condition.Finally,the experimental results are discussed.展开更多
The synchrotron radiation from a new wiggler of BEPC has been used to high pressure research. Upgraded DAC apparatus and EDXD system have been operated to determine the pressure-induced phase transition of materials a...The synchrotron radiation from a new wiggler of BEPC has been used to high pressure research. Upgraded DAC apparatus and EDXD system have been operated to determine the pressure-induced phase transition of materials at BSRF since June 1998. The improved performance of the system and the preliminary results of the research were described.展开更多
基金the National Natural Science Foundation of China。
文摘The compression and polymorphic phase transitions of iodine have been studied by using x-ray diffraction with a diamond anvil cell at high pressure up to 77GPa.Considering that iodine is reactive with iron in air,a corrosion-resisting and high-strength gasket was put between the diamonds,thus the sample can be mounted at atmospheric pressure and room temperature.Pressure was measured in terms of the ruby fluorescence and the molybdenum diffraction as an internal pressure standard.According to the x-ray diffraction results,the iodine undergoes the following three structural phase transitions with pressure increasing:(1)At 21 GPa,from base centred orthorhombic phase(phase Ⅰ)to body centred orthorhombic phase(phase Ⅱ).A 2%change in volume occurs.(2)At 44 GPa,from phase II to body centred tetragonal phase(phase Ⅲ).This is a second order phase transition.(3)At 71 GPa,from phase III to fcc phase(phase Ⅳ).The volume decreases by 3%.At this time,the volume is 45%of the original one at atmospheric pressure.
基金C_(60)sample is provided by LI Yuliang and YAO Youxin,Institute of Chemistry,Academia Sinica.This research is supported by the Beijing Synchrotron Radiation Laboratory,Institute of High Energy Physics,Academia Sinica,and the National Natural Science Foundation of China.
文摘Based on in situ high pressure x-ray diffraction with diamond anvil cell by using synchrotron radiation and pressure-quench x-ray measurement,phase transition of C_(60)under high pressured is studied.The maximum pressure used is 30GPa in quasi-hydrostatic case but 44GPa in nonhydrostatic case.At ambient pressure,C_(60)crystal is a fcc phase with lattice parameter a=14.2086Å.It transforms from fcc to a lower symmetry phase at pressure of 13.7GPa,and then transforms to an amorphous state under pressure up to 25-30 GPa.This amorphous state is metastable at normal condition.Finally,the experimental results are discussed.
文摘The synchrotron radiation from a new wiggler of BEPC has been used to high pressure research. Upgraded DAC apparatus and EDXD system have been operated to determine the pressure-induced phase transition of materials at BSRF since June 1998. The improved performance of the system and the preliminary results of the research were described.
