Effects of ZnO addition and microwave sintering on the properties of BaCe0.2Zr0.7Y0.1O3-δ proton conductor electrolyte

The reduction of sintering time and temperature using an unconventional route and sintering aid for the densification of BaCe0.2Zr0.7Y0.1O3-δ were investigated. The effects of ZnO addition and microwave sintering were explored on the structure, sinterability, microstructure, and electrical conductivity. BaCe0.2Zr0.7Y0.1O3-δ powders were synthesized by solid-state reaction. The addition of 2 and 4 mol% ZnO was beneficial to obtain a single perovskite structure and improved sinterability producing dense samples. Relative densities of 99% at 1300 °C by conventional sintering and 98% at 1400 °C by microwave sintering were reached. A total conductivity of 1.20 mS cm−1 for the sample with 2 mol% ZnO by conventional sintering (relative density 99%) was obtained at 550 °C in a wet nitrogen atmosphere. Additionally, a high conductivity was also obtained for this compound produced by microwave sintering (relative density 98%) even with its microstructure exhibiting the smallest average grain size. In conventional sintering, the presence of the eutectic liquid phase responsible for the densification, was prejudicial to the total conductivity, being more evident in the samples with 4 mol% ZnO addition. The results indicate that microwave sintering was a rapid alternative for sintering, capable of reducing or inhibiting the appearance of the liquid phase producing dense, uniform samples, and with high conductivity.