Ab initio investigation of the thermophysical properties of barium orthovanadate

Abstract

Metal vanadates have garnered widespread attention across various scientific fields due to their exceptional performance. In this work, we investigate the lattice dynamics and thermophysical properties of barium orthovanadate (Ba₃V₂O₈) using first-principles calculations. We provide reliable thermodynamic data, including entropy and heat capacity across a broad temperature range. The complex crystal structure of Ba₃V₂O₈ leads to strong phonon anharmonicity, which greatly suppresses the contribution of propagative phonons to the lattice thermal conductivity (κ_L). Moreover, utilizing the unified theory, we find that the significant contribution of coherent phonon transport makes κ_L exhibit low-temperature dependence. Notably, coherent phonons along the a-axis begin to exceed the contribution of propagative phonons at around 400 K and reach a high proportion of 71.9% at 800 K, leading to an anomalous change in κ_L. This research emphasizes the significant impact of strong anharmonicity and coherent phonon channels on the thermal transport process in Ba₃V₂O₈, providing a crucial perspective for predicting and understanding the thermophysical properties of metal vanadates and contributing to the further regulation of the thermal transport characteristics.