Pressure induced electronic and structural transition in Ba2NiTeO6

This study explores the pressure evolution of the double perovskite BaNiTeOby employing experimental and computational techniques. For the study of structural and vibrational properties, synchrotron x-ray diffraction and micro-Raman spectroscopic experiments at high-pressures were carried out. As a complementary study, DFT simulations of the structural properties as a function of pressure were performed to support and explain the experimental findings. Furthermore, the electronic and magnetic properties as a function of pressure were investigated using DFT. Our study reveals a structural phase transition from a rhombohedralto a monoclinicphase at high pressure, accompanied by a significant increase in bulk modulus. Raman anomalies near 1 GPa coincide with a calculated direct-to-indirect band-gap crossover, suggesting a possible electronic contribution to the vibrational response. A minimum in the Raman mode full-width-half-maximum (FWHM) at about 11 GPa, coincides with a local structural reorganization in the sample, indicated by a drop in the distortion index of NiOoctahedra as well as a discontinuity in theratio.