Abstract
The effect of pressure on the structural, vibrational, and electronic properties of Mg-doped Cr bearing spinel was studied up to 55 GPa at room-temperature using x-ray diffraction, Raman spectroscopy, electrical transport measurements, and ab initio calculations. We found that the ambient-pressure phase is cubic (spinel-type, ) and underwent a pressure-induced structural transition to a tetragonal phase (space group ) above 28 GPa. The ab initio calculation confirmed this first-order phase transition. The resistivity of the sample decreased at low pressures with the existence of a low-pressure (LP) phase and started to increase with the emergence of a high-pressure (HP) phase. The temperature dependent resistivity experiments at different pressures illustrated the wide band gap semiconducting nature of both the LP and HP phases with different activation energies, suggesting a semiconductor-semiconductor transition at HP. No evidence of chemical decomposition or a semiconductor-metal transition was observed in our studies.
- Received 2 February 2018
- Revised 23 April 2018
DOI:https://doi.org/10.1103/PhysRevB.97.174102
©2018 American Physical Society