Ambient pressure synthesis and H-conductivity of LaSrLiH2O2

Abstract

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 solidstate 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 × 10-6Scm-1 at 300°C, which were the same structure and property as that reported previously for a sample synthesized by high-pressure synthesis.