Multiferroic CuCrO2 under High Pressure: In-Situ X-Ray Diffraction and Raman Spectroscopic Studies

TL;DR

This study investigates the high-pressure structural and vibrational behavior of CuCrO2, revealing its stability up to 23 GPa, anisotropic compression, a phase transition around 24 GPa, and potential transformation to a rocksalt structure.

Contribution

First in-situ X-ray diffraction and Raman spectroscopic analysis of CuCrO2 under high pressure, identifying phase transition and structural stability up to 23 GPa.

Findings

CuCrO2 remains structurally stable up to ~23 GPa.

A new Raman mode appears at ~24 GPa indicating a phase transition.

Potential transformation to an ordered rocksalt structure under high pressure.

Abstract

The compression behavior of delafossite compound CuCrO2 has been investigated by in-situ x-ray diffraction and Raman spectroscopic measurements upto 23.2 and 34 GPa respectively. X-ray diffraction data shows the stability of ambient rhombohedral structure upto ~ 23 GPa. Material shows large anisotropy in axial compression with c-axis compressibility, c= 1.2610-3(1) GPa-1 and a-axis compressibility, a= 8.9010-3(6) GPa-1. Our XRD data shows an irreversible broadening of diffraction peaks. Pressure volume data when fitted to 3rd order Birch-Murnaghan equation of state gives the value of bulk modulus, B0 = 156.7(2.8) GPa with its pressure derivative, B0' as 5.3(0.5). All the observed vibrational modes in Raman measurements show hardening with pressure. Appearance of a new mode at ~24 GPa indicates the structural phase transition in the compound. Our XRD and Raman results indicate that CuCrO2 may be transforming to an ordered rocksalt type structure under compression.