Proton conductivity of potassium doped barium zirconates

Xu, Xiaoxiang and Tao, Shanwen and Irvine, John T. S. (2010) Proton conductivity of potassium doped barium zirconates. Journal of Solid State Chemistry, 183 (1). pp. 93-98. ISSN 0022-4596

Abstract

Potassium doped barium zirconates have been synthesized by solid state reactions. It was found that the solubility limit of potassium on A-sites is between 5% and 10%. Introducing extra potassium leads to the formation of second phase or YSZ impurities. The water uptake of barium zirconates was increased even with 5% doping of potassium at the A-site. The sintering conditions and conductivity can be improved significantly by adding 1 wt% ZnO during material synthesis. The maximum solubility for yttrium at B-sites is around 15 at% after introducing 1 wt% zinc. The conductivity of Ba0.95K0.05Zr0.85 Y0.11Zn0.04O3-delta at 600 degrees C is 2.2 x 10(-3) S/cm in wet 5% H-2. The activation energies for bulk and grain boundary are 0.29(2), 0.79(2)eV in wet 5% H-2 and 0.31(1), 0.74(3)eV in dry 5% H-2. A power density of 7.7 mW/cm(2) at 718 degrees C was observed when a 1 mm thick Ba0.95K0.05Zr0.85Y0.11Zn0.04O3-delta pellet was used as electrolyte and platinum electrodes.

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