Densification of proton-conducting ABO3 (A = Ca, Sr, Ba; B = Zr, Hf) based ceramics: Review of sintering technologies and their impact on charge transport properties

Abstract

Alkaline-earth zirconates and hafnates represent a class of proton-conducting perovskites characterized by superior chemical stability compared to other perovskite families. This makes them promising electrolytes for solid oxide fuel cells, electrolyzers and other electrochemical devices. One of the key requirements to ceramic electrolytes is a high density to isolate the fuel and oxidizing gases. However, manufacturing dense ceramics is a big challenge when processing refractory materials. Conventional solid-state sintering requires prolonged exposure to high temperatures, which leads to an increase in the production cost and to alteration of chemical stoichiometry and thus transport properties. Different technologies are used nowadays to sinter dense ceramics at lower temperatures and shorter durations. The present paper summarizes the sintering technologies of proton-conducting ABO3 based ceramics, examines their advantages and limitations, and analyses the technology impact on the functional properties of electrolytes. Comparative analysis of the microstructural and transport properties of ceramics obtained by different technologies is provided.