Strain Induced Relaxor-type Ferroelectricity Near Room Temperature in Delafossite CuCrO2

TL;DR

This study reveals that CuCrO2, a delafossite compound, exhibits relaxor-type ferroelectricity near room temperature due to strain-induced polar regions, a property previously unnoticed in this material.

Contribution

It demonstrates that strain from distorted CrO6 octahedra induces relaxor ferroelectricity in CuCrO2 near room temperature, a novel finding for this material system.

Findings

Presence of relaxor ferroelectricity near room temperature in CuCrO2.

Strain from distorted CrO6 octahedra causes polar region formation.

Dielectric permittivity shows broad maximum and frequency dispersion.

Abstract

Polycrystalline samples of CuCrO2 were synthesized by solid state reaction method. Temperature dependent dielectric measurements, synchrotron x-ray diffraction (SXRD), pyroelectric current and Raman measurements have been performed on these samples. Evidences of the presence of relaxor type ferroelectricity, which otherwise have gone unnoticed in CuCrO2 system (a member of delafossite family) near room temperature, have been presented. Presence of broad maximum in dielectric permittivity and its frequency dispersion indicates relaxor-type ferroelectricity in CuCrO2 near room temperature. Careful analysis of temperature dependent SXRD data and Raman spectroscopic data indicates that the distorted CrO6 octahdera, is giving rise to strain in the sample. Due to this strain, polar regions are forming in an otherwise non-polar matrix, which is giving rise to relaxor type ferroelectricity in the sample. Regularization of CrO6 octahedra and disappearance of disorder induced peak in Raman spectra at high temperatures could be the reason behind observed dielectric anomaly in this sample. Present investigations propose that relaxor type ferroelectricity near room temperature is an inherent property of the CuCrO2 system, making it a fascinating material to be explored further.