Phase Diagram of the Li4GeS4-Li3PS4 Quasi-Binary System Containing the Superionic Conductor Li10GeP2S12

• Published in: Journal of the American Ceramic Society Vol. 98; no. 10; pp. 3352 - 3360
• Main Authors: Hori, Satoshi, Kato, Masahiko, Suzuki, Kota, Hirayama, Masaaki, Kato, Yuki, Kanno, Ryoji
• Format: Journal Article
• Language: English
• Published: Columbus Blackwell Publishing Ltd 01.10.2015; Wiley Subscription Services, Inc
• Subjects: Binary system; Binary systems; Conductors; Crystal structure; Lithium; Phase diagrams; Solid solutions
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.13694

A phase diagram is constructed for the quasi‐binary Li4GeS4–Li3PS4 system containing the lithium superionic conductor Li10GeP2S12 (LGPS), having an LGPS‐type structure, and the β‐Li3PS4‐type phase, having a thio‐LISICON structure. The LGPS and thio‐LISICON intermediate compounds are found to exhibit solid solution ranges and show incongruent melting at 650°C and 560°C, respectively. The end‐member Li4GeS4 has a compositional range of 0 < k < 0.3 in [(1−k) Li4GeS4 + k Li3PS4], while the other end‐member γ‐Li3PS4 has no solid solution range. The crystal structures appearing in the binary systems are the α‐, β‐, and γ‐type Li3PS4 structures and the LGPS‐type structure, and these are formed by PS4 tetrahedra with different arrangements in each structure. The phase and structural relationships between the compounds appearing in the Li4GeS4–Li3PS4 system are thus clarified.