Advanced Ba0.5Sr0.5Zn0.2Fe0.8O3−δ perovskite-type ceramics as oxygen selective membranes: Evaluation of the synthetic process

A synthetic route for advanced perovskites is elucidated that consists of a combined EDTA/citrate complexing of metal cations and the subsequent drying and firing at moderate temperatures. A fine-scale intermixing of cations is maintained during all the processing steps. The perovskite-type oxide is formed already in an intermediate step at 700 °C by the reaction of an ultra-finely dispersed powder consisting of a mixed barium–strontium carbonate, a zinc–iron spinel, and zinc oxide. The process yields powders of good sinterability and finally dense ceramics composed of stoichiometric perovskite grains of the type (Ba,Sr)(Zn,Fe)O3−δ.