The effect of pressure on the structural evolution, enhancement of photoluminescence intensity and optical band gap of a vacancy ordered double halide perovskite Cs2TeCl6 is investigated systematically. We use synchrotron x-ray diffraction, Raman spectroscopy, optical band gap and photoluminescence measurements to explore the structural and the optical properties of Cs2TeCl6 under pressure up to 30.0 GPa. We find that Cs2TeCl6 undergoes a structural transition from cubic Fm3ˉm to monoclinic P21/n at very low pressure below 1.0 GPa. A significant increase in photoluminescence intensity and a rapid decrease in optical band gap are observed, which are related to the octahedral distortion and structural transition. Interestingly, with increasing pressure, the sample regains its ambient Fm3ˉm structure at around 3.4 GPa maintaining the cubic phase up to 30.0 GPa. The sample undergoes an iso-structural transition at around 14.1 GPa pressure with a slight decrease in compressibility.
@article{arxiv.2501.05705,
title = {Structural transition and emission enhancement in vacancy ordered halide double perovskite Cs$_2$TeCl$_6$ under pressure},
author = {Suvashree Mukherjee and Debabrata Samanta and Bidisha Mukherjee and Konstantin Glazyrin and Goutam Dev Mukherjee},
journal= {arXiv preprint arXiv:2501.05705},
year = {2025}
}