Improvement of sinterability of BaZr0.8Y0.2O3-δ for H2 separation using Li2O/ZnO dual-sintering aid

Abstract

Li2O/ZnO was used as a dual-sintering aid to improve sintering performance of BaZr0.8Y0.2O3-δ electrolyte (BZY). The influences of the Li/Zn ratios on sinterability, phase composition, microstructure and electrochemical properties of BZY electrolyte were investigated. Using Li2O/ZnO as a dual-sintering additive, high density BZY ceramics were obtained at reduced temperature. The BZY samples added Li2O/ZnO dual-sintering aid had better performance than that using Li2O or ZnO single sintering aid. When total amount of Li and Zn in the form of oxides was controlled at 4 mol%, the BZY sample with the Li/Zn molar ratio of 1:1 achieved the highest relative density of 95.6% at temperature as low as 1400 °C and its total conductivity was found to be equal to 6.90 × 10−3 S cm−1 in wet air at 700 °C. The BZY samples also exhibited excellent chemical stability under CO2 or H2O atmosphere. These results showed that Li2O/ZnO was an excellent dual sintering additive for lowering the sintering temperature and increasing electrical conductivity of BZY. The hydrogen permeation performance of the above-mentioned BZY membrane with the Li/Zn molar ratio of 1:1 was evaluated using external short circuit method with porous Pt as catalyst and sliver sealing layer as electronic conductor. It was observed that hydrogen permeation flux increased with the increasing of temperature and hydrogen content in feed gas. When 50% H2–N2 was fed, the hydrogen flux reached 0.091 ml/min cm2 at 800 °C for the BZY membrane with a thickness of 1.0 mm.