Pressure-assisted synthesis of a new Mg2+ conductive ternary sulfide

This project aims at stabilizing the still unpublished cubic spinel form of MgAl2S4 by using high pressure / high temperature solid state synthesis. Chalcospinel are promising materials that could be used as ionic conductors for Mg-ion solid state type batteries. To date, only MgSc2Se4 compound has been experimentally obtained. It has good room temperature ionic conductivity but selenium and scandium are toxic and expensive, respectively. We thus propose another composition, made of cheaper, non-toxic and more sustainable elements, MgAl2S4. Ambient pressure solid state reaction could not lead to the formation of a spinel phase up to 1100°C. Preliminary trials in a Paris-Edinburg press at IMPMC lab show that high-pressure (4.5 GPa) and high temperature (up to 1800°C) can stabilize the cubic spinel form of MgAl2S4. Our objective is to gain deeper insight into the mechanisms governing this reaction in order to optimize the synthesis conditions of pure spinel phase.