A comparative proton conductivity study on Yb-doped BaZrO3 perovskite at intermediate temperatures under wet N2 environment

Conventional solid state reaction route was used for the synthesis of oxygen deficient BaZr1−xYbxO3-δ (x = 0.05, 0.10, 0.15, 0.20) oxide. Rietveld refinement of x-ray diffraction data confirmed the formation of mono-phasic cubic perovskite structure with space group Pm3¯m. The microstructure coupled with EDX analysis of the sintered ceramics reveals the formation of sub-micron sized grains, with no detection of impurity elements. Thermogravimetric analysis of the pre-hydrated sample shows a significant mass loss suggesting complete filling of oxygen vacancies by protonic defects. Impedance spectroscopy performed under wet N2 environment show highest proton conductivity for the composition with x = 0.20. The total conductivity at 600 °C significantly increased from the order of 10−5 Scm−1 for x = 0.05 to 10−3 Scm−1 for x = 0.20 composition. The activation energy calculated from the Arrhenius dependence of total conductivity decreased with an increase in trivalent Yb3+ concentration, since the number of charge carriers in the form of protonic defects increases.