Crystal Structure of High-Temperature Phase of Lithium Ionic Conductor, Li3PS4

Crystal structure of the high-temperature phase of lithium ionic conductor, Li3PS4, was determined using high-temperature synchrotron X-ray diffraction data. Li3PS4 belongs to the thio-LISICON (Lithium Super Ionic CONductor) family and shows high ionic conductivity above 500 K. The high-temperature alpha phase with space group, Pbcn(60), has an orthorhombic cell parameter, a = 8.6125(2) angstrom, b = 9.0211(2) angstrom, and c = 8.42621(2) angstrom at 906 K. The PS4 tetrahedra are isolated with each other and form an alternating T+ row and T- row, where T+ and T- indicate that the apex of the tetrahedra is up and down, respectively. These PS4 arrangements are different from those of the medium temperature beta-phase and the low-temperature gamma-phase.