2018 Volume 65 Issue 1 Pages 26-33
This study investigated the conductivity of lithium ions in new pyrochlore materials. A two-step synthesis method, comprising a simple solid-state reaction followed by a high-pressure solid-state reaction was used to synthesize single-phase undoped LiSrB2O6F (where B = Nb5+ or Ta5+). The samples were doped with the lower valent cation, Zr4+, which replaced Nb5+ or Ta5+ at B-sites in LiSrB2O6F and similarly, A-site point defects were introduced by reducing the amount of Sr in the sample. The crystal structure was determined by Rietveld analysis of the X-ray synchrotron diffraction data. Ionic conductivities of the samples were evaluated using electrochemical impedance spectroscopy. Sr2+ deficient samples showed better conductivity (8.21 × 10−6 S cm−1 for Nb-containing samples and 6.38 × 10−6 S cm−1 for Ta-containing samples at 300°C) than that of Zr4+-doped samples (5.58 × 10−6 S cm−1 for Nb-containing samples and 3.58 × 10−6 S cm−1 for Ta-containing samples at 300°C).