F anion dynamics in cation-mixed nanocrystalline LaF3: SrF2

作者：Stefan Breuer, S. Lunghammer, A. Kiesl, M. Wilkening · 发表于：Journal of Materials Science · 年份：2018 · DOI：10.1007/s10853-018-2361-x · 被引用次数：39 · 研究领域：Materials Science

AbstractIon dynamics in nanocrystalline materials can be quite different compared to that in materials with $$\upmu $$μm-sized crystallites. In particular, the substitution of iso- or aliovalent ions opens pathways to systematically control ion transport properties. Here we studied the incorporation of $${\text {SrF}}_2$$SrF2 into the tysonite structure of $${\text {LaF}}_3$$LaF3 and its effect on F$$^{-}$$- transport. High-energy ball milling directly transforms the binary fluorides in a structurally disordered, phase pure nanocrystalline ceramic. Compared to Sr-free $${\text {LaF}}_3$$LaF3, ionic conductivity could be increased by several orders of magnitude. We attribute this enhancement to the generation of lattice strain and the formation of F defect sites. In agreement with this increase, the activation energy $$E_{{\mathrm{a}}}$$Ea of long-range ionic transport in the solid solution $${\text {La}}_{1-x}{\text {Sr}}_{x}{\text {F}}_{3-x}$$La1-xSrxF3-x significantly decreases from 0.75 eV ($$x=0$$x=0) to 0.49 eV ($$x=0.1$$x=0.1).