Enhanced sintering of yttrium-doped barium zirconate by addition of ZnO

Abstract

The influence of transition metal oxides additives, especially zinc oxide, on the densification and electrical properties of doped barium zirconate have been examined. With the use of zinc oxide as a sintering aid, BaZr_(0.85)V_(0.15)O_(3-δ) was readily sintered to above 93% of theoretical density at 1300 degrees C. Scanning electron microscopic investigations showed Zn accumulation in the intergranular regions. Thermogravimetric analysis of the material under flowing CO_2 showed ZnO-modified barium zirconate to exhibit excellent chemical stability. The conductivity, as measured by A.C. impedance spectroscopy under H_2O saturated nitrogen, was slightly lower than that of unmodified barium zirconate. Electromotive force measurements under fuel cell conditions revealed the total ionic transport number to be ~0.9 at 600 degrees C. The combination of electrical and chemical properties and good sinterabifity render ZnO-modified barium zirconate an excellent candidate for reduced temperature solid oxide fuel cell applications