The goal of this proposal is to characterize the evolution of the crystal structure as a function of pressure, at room temperature and high temperature, of double fluorite superionic conductors; MSnF4 (M= Ba, Sr, Pb). Fluoride ion batteries have emerged as high-energy-density energy storage devices, with superionic MSnF4 compounds serving as solid-state electrolytes. The practical application of MSnF4 compounds is highly dependent upon the intricate play between temperature, pressure, and ionic conductivity. This project aims to comprehensively study the pressure and temperature-dependent structural behavior of these materials, to understand the behavior of their ionic conductivity in relation to temperature and pressure, to advance their application as solid-state electrolytes and barocaloric materials.