[1Ga01-10] Thin Film (TF)

[1Ga08] Fabrication of La_0.95Sr_0.05F_2.95 epitaxial thin films and evaluation of F⁻ conduction properties

*Kazusa Takahashi¹, Ryota Shimizu², Asuka Oi¹, Kehan Huo², Shigeru Kobayashi², Kazunori Nishio¹, Taro Hitosugi^2,1 (1. Tokyo Institute of Technology, 2. The University of Tokyo)

Alkaline-earth doped lanthanum trifluoride (La_1−xBa_xF_3−x, La_1−xSr_xF_3−x) has attracted much attention as a solid electrolyte in all-solid-state fluoride ion batteries. Aiming for quantitative evaluation of F⁻ conductivity, we reported the fabrication of La_1−xBa_xF_3−x epitaxial thin film. However, since Ba is located next to La in the periodic table, it is difficult to analyze the composition of the thin films, hindering the exact amount of substitution. In this study, we focus on Sr instead of Ba, and report on the fabrication of La_1−xSr_xF_3−x (x=0.05) epitaxial thin films using reactive sputtering and the characterization of their ionic conductivity. By tuning the partial pressure of CF₄ as a reactive gas during sputtering, we successfully fabricated (001)-oriented La_0.95Sr_0.05F_2.95 epitaxial thin films. Thus, we obtained F⁻ conductivity of ~6.6×10⁻³ Scm⁻¹ at 150°C, consistent with that in bulk.