Recently, hydride ion (H−) has come to be recognized as new charge carrier for the transport of hydrogen in solids by realization of pure H− conduction in BaH2 and La2−x−ySrx+yLiH1−x+yO3−y oxyhydride system (LSLHO). In this study, the H− conductive oxyhydride, LaSrLiH2O2 (x = 0, y = 1 in LSLHO), was synthesized by a conventional solid-state reaction at ambient pressure. The crystal structure of LaSrLiH2O2, as well as the H− conductivity and bonding state of hydrogen, was examined by Rietveld analysis using X-ray and neutron diffraction data, attenuated total reflection Fourier transform spectroscopy (ATR-FTIR), and electrochemical impedance spectroscopy (EIS). The sample synthesized at ambient pressure had a K2NiF4-type layered perovskite structure composed of alternately stacked tetragonal (LiH2)− and (LaSrO2)+ layers, and exhibited a conductivity of H− of 3.2 × 10−6 S cm−1 at 300°C, which were the same structure and property as that reported previously for a sample synthesized by high-pressure synthesis.
2017 The Electrochemical Society of Japan