Anomalous high-pressure behavior of amorphous selenium from synchrotron x-ray diffraction and microtomography.
The high-pressure behavior of amorphous selenium has been investigated with time-resolved diamond anvil cell synchrotron x-ray diffraction and computed microtomography techniques. A two-step dynamic crystallization process is observed in which the monoclinic phase crystallized from the amorphous selenium and gradually converted to the trigonal phase, thereby explaining previously observed anomalous changes in electrical conductivity of the material under pressure. The crystallization of this elemental system involves local topological fluctuations and results in an unusual pressure-induced volume expansion. The metastability of the phases involved in the transition accounts for this phenomenon. The results demonstrate the use of pressure to control and directly monitor the relative densities and energetics of phases to create new phases from highly metastable states. The microtomographic technique developed here represents a method for determination of the equations of state of amorphous materials at extreme pressures and temperatures.
Liu
Haozhe
H
Natural Science Research Center, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080, China. haozhe@hit.edu.cn
Wang
Luhong
L
Xiao
Xianghui
X
De Carlo
Francesco
F
Feng
Ji
J
Mao
Ho-Kwang
HK
Hemley
Russell J
RJ