Ambient-temperature incorporated hydrogen in Nb:SrTiO₃ single crystals

Abstract

Electrolysis of water has been implemented to inject hydrogen into the SrTiO₃ single crystal doped with 1 wt% of Nb. Direct evidence of OH‾ group formation in the Nb:SrTiO₃ single crystal has been obtained by Fourier-transform infrared (FTIR) analysis, showing an intensity increase of the absorption at a wave number of about 3500 cm‾¹. FTIR analysis also revealed lattice relaxation due to hydrogen doping. High-resolution x-ray diffraction (XRD) analysis further illustrated lattice expansion, as evidenced by the left shift of the SrTiO₃ (200) peak for the hydrogen doped sample. The decrease in the XRD rocking curve linewidth of this (200) peak for the hydrogen-doped sample suggested that hydrogen doping relaxed the local constraints in the crystal. In contrast to the usual great increase in conductivity of insulating perovskite oxides by hydrogen doping, an obvious decrease in conductivity of the highly conductive Nb:SrTiO₃ single crystal was observed after hydrogen doping.