We have conducted a detailed high-pressure (HP) investigation on Eu−doped BaTiO3 using angle-resolved x-ray diffraction, Raman spectroscopy, dielectric permittivity and dc resistance measurements. The x-ray diffraction data analysis shows a pressure-induced structural phase transition from the ambient tetragonal to the mixed cubic and tetragonal phase above 1.4 GPa. The tetragonality of the sample due to the internal deformation of the TiO6 octahedra caused by charge difference from Eu doping cannot be lifted upon by pressure. Softening, weakening, and disappearance of low-frequency Raman modes indicate ferroelectric tetragonal to the paraelectric cubic phase transition. But the pressure-induced increase in the intensity of [E(LO), A1(LO)] and the octahedral breathing modes indicate the local structural inhomogeneity remains in the crystal and is responsible for spontaneous polarization in the sample. Low-frequency electronic scattering response suggests the pressure-induced carrier delocalization, leading to a semi-metallic state in the system. Our HP dielectric constant and dc resistance data can be explained by the presence of pressure-induced localized clusters of microscopic ferroelectric ordering. Our results suggest HP phase coexistence leads to a ferroelectric-like semi-metallic state in Eu−doped BaTiO3 under the extreme quantum limit.
@article{arxiv.2303.02329,
title = {High pressure ferroelectric-like semi-metallic state in $Eu-$doped $BaTiO_3$},
author = {Mrinmay Sahu and Bishnupada Ghosh and Bobby Joseph and Goutam Dev Mukherjee},
journal= {arXiv preprint arXiv:2303.02329},
year = {2023}
}