Influence of Gallium Substitution on the Crystal and Electronic Properties of Li5Ca1-xGaxLa3Zr2O12 Solid State Battery Electrolyte

In this study, calcium doped Li7La3Zr2O12 (LLZO) were synthesized as a candidate for the solid state electrolyte material according to the Li7-2x CaxLa3Zr2O12 (LCLZO) general formula where x has the value "1.0" and also the parent material for the sample series of Li5Ca1- xGaxLa3Zr2O12. Crystal and electronic properties of the LCLZO materials were studied in two steps; Ca2+ substitution to Li+ coordinations and Ga3+ substitution to Ca2+ coordinations. Analysis confirmed that a calcium sit in two lithium coordinations, however, the Ca2+ doped LCLZO material were determined in tetragonal structure, not cubic, which has lower properties for battery electrolytes. In the second step of the study, with the attempt of the substitution of the Ga3+ ions to the Ca2+ coordinations, the phase of the tetragonal LCLZO structures changed to cubic LCLZO structure. According to the XAS analysis of the O K-edge spectra, it is determined that oxygen coodinations are the main role player in the samples and cause the formation of the “Li5GaO4” structures with the Ga3+ substitution.