Stabilizing High-Temperature α-Li ₃ PS ₄ by Rapidly Heating the Glass

High-temperature metastable phases exhibit superior characteristics compared to those of thermodynamically stable phases at room temperature. Although optimization of the compositions and crystallizations from glasses contribute to the stabilization of metastable phases at room temperature, the stabilization of the high-temperature α-Li 3 PS 4 phase is not yet reported. α-Li 3 PS 4 was successfully stabilized at room temperature, instead of the middle-temperature β-Li 3 PS 4 phase, via rapid heating to crystallize the Li 3 PS 4 glass. The obtained electrolyte exhibited a high ionic conductivity of >10 –3 S cm –1 at room temperature. The crystallization of the glass via rapid heating overcame the thermodynamic limitations in the preparation of the metastable crystals. Further development of materials via nonequilibrium states should contribute to the design of high-performance materials.