A Study on Sintering Behavior and Conductivity for NiO-doped BaZr_0.85Y_0.15O_3-δ

Abstract

>> Perovskite-type oxides such as doped barium zirconate (BaZrO3) show high proton conductivity and chemical stability when they are exposed to hydrogen and water vapour containing atmospheres, thus it can be applicable to the hydrogen separation and the fuel cell electrolyte membranes. However the high temperature (1700-1800℃) and long sintering times (24h) are generally required to prepare the fully densified BaZrO3 pellets. These sintering conditions lead to the limitation of the grain size growth and the degradation of conductivity due to the acceleration of BaO evaporation at 1200℃. Here we demonstrate NiO-doped BaZr0.85Y0.15O3-δ with lower calcination and sintering temperature, less experimental procedure and lower process cost than the conventional mixing method. The stoichiometry of BaZr0.85Y0.15O3-δ was optimized by the control of excess amount of Ba (5mol%) to minimized BaO evaporation. We found that the crystal size of NiO-doped BaZr0.85Y0.15O3-δ was increased with increase of calcination temperature from XRD analysis. NiO-doped BaZr0.85Y0.15O3-δ powder was calcined at 1000℃ for 12h when its showed the highest conductivity of 3.3ⅹ10 -2 s/cm.