Stable BaCl solid at high pressure: Prediction and characterization using first principles approach

Industrial processes involving the manufacture of heat treatment salts such as BaCl at high pressures are becoming possible. Hence, there is a need to search for a specific form of BaCl with excellent thermal properties. Motivated by this, the potential energy surface of BaCl is extensively explored using the unbiased particle swarm-intelligence optimization algorithm to uncover a global minimum enthalpy phase of BaCl within the pressure range that was recently experimentally explored. Previously predicted phases were confirmed during the structure search. Furthermore, the orthorhombic Pnma form of BaCl is predicted to be more stable and energetically more favorable than the previously predicted R-3m phase in the pressure range of ∼10–15 GPa. The electronic and thermal properties of the newly discovered phase are extensively studied using first principles calculations. In the pressure range of interest, Pnma BaCl is metallic and nonmagnetic. More so, the solution of the Boltzmann Transport Equation unravels promising thermal properties, which make Pnma BaCl a good candidate for heat management in high temperature systems. We found the overall Grüneisen parameters in Pnma BaCl to range between 0.963 and 0.995 and the lattice thermal conductivity at 300 K to be 53.7 W m⁻¹K⁻¹. We also found that Pnma BaCl exhibits anisotropy that we observed is constant in all directions explored.