Pressure-Induced Structural Phase Transition and Metallization in Ga2Se3 Up to 40.2 GPa under Non-Hydrostatic and Hydrostatic Environments

Meiling Hong,Haiying Hu,Xinyu Zhang,Lidong Dai

doi:10.3390/cryst11070746

Abstract

A series of investigations on the structural, vibrational, and electrical transport characterizations for Ga2Se3 were conducted up to 40.2 GPa under different hydrostatic environments by virtue of Raman scattering, electrical conductivity, high-resolution transmission electron microscopy, and atomic force microscopy. Upon compression, Ga2Se3 underwent a phase transformation from the zinc-blende to NaCl-type structure at 10.6 GPa under non-hydrostatic conditions, which was manifested by the disappearance of an A mode and the noticeable discontinuities in the pressure-dependent Raman full width at half maximum (FWHMs) and electrical conductivity. Further increasing the pressure to 18.8 GPa, the semiconductor-to-metal phase transition occurred in Ga2Se3, which was evidenced by the high-pressure variable-temperature electrical conductivity measurements. However, the higher structural transition pressure point of 13.2 GPa was detected for Ga2Se3 under hydrostatic conditions, which was possibly related to the protective influence of the pressure medium. Upon decompression, the phase transformation and metallization were found to be reversible but existed in the large pressure hysteresis effect under different hydrostatic environments. Systematic research on the high-pressure structural and electrical transport properties for Ga2Se3 would be helpful to further explore the crystal structure evolution and electrical transport properties for other A2B3-type compounds.

Highlights

In recent decades, A2 B3 -type (A: Ga, In; B: S, Se, Te) metal chalcogenides have drawn considerable interest due to their extensive applications in the field of photovoltaic devices, IR detectors, and nuclear particle detection devices [1,2,3,4]
We report the structural transition and metallization for Ga2 Se3 at pressures up to 40.2 GPa using a diamond anvil cell in conjunction with Raman scattering, AC
The high-pressure structural, vibrational, and electrical transport properties for Ga2 Se3 were comprehensively studied in a diamond anvil cell up to 40.2 GPa under different hydrostatic environments using Raman spectroscopy, AC impedance spectroscopy, highresolution transmission electron microscopy, and atomic force microscopy

Summary

Introduction

A2 B3 -type (A: Ga, In; B: S, Se, Te) metal chalcogenides have drawn considerable interest due to their extensive applications in the field of photovoltaic devices, IR detectors, and nuclear particle detection devices [1,2,3,4]. Pressure is capable of modulating the atomic distances, positions, and interactions in most A2 B3 -type semiconducting compounds, and leads to some novel physical phenomena such as the pressure-induced structural transition, metallization, and amorphization [9,10,11,12,13]. As far as Ga2 Se3 is concerned, its high-pressure phase stability and structural transition have been investigated by synchrotron X-ray diffraction, electrical resistance, and thermoelectric power [14,15]. Savchenko and Shchennikov (1994) performed the electrical resistance and thermoelectric power experiments for Ga2 Se3 using a diamond anvil cell up to 35.0 GPa [14]. The authors found apparent discontinuities in the pressuredependent electrical resistance and thermoelectric power at 14.2 GPa and attributed it to a semiconductor-to-semiconductor structural transition.

Methods

Results

Conclusion