The Formation of Stacking Faults in Barium Zirconate-Type Perovskites

High Resolution Image Download MS PowerPoint Slide Yttrium-doped barium zirconate (BZY) is a proton-conducting perovskite with potential for use in a variety of energy applications, including as a catalyst support and as an electrolyte for solid-state fuel and electrolytic cells. Of interest to material performance is the presence and character of defects in the material, which will influence material properties. The presented work discusses the discovery of stacking faults in conventionally sintered BZY at different measured A / B ratios (Ba x Zr 0.8 Y 0.2 O 3−δ, x = 0.989, 1.001, and 1.006). Two structurally unique stacking faults are observed for the first time in BZY, i.e., Ruddlesden–Popper (RP) type and non-RP type. Characterization using S/TEM details the presence of stacking faults and dislocations and provides insight into the formation process of RP-type faults in BZY-type materials. Electrochemical impedance spectroscopy is performed to analyze the impact of stacking faults on material conductivity. The stacking faults are concluded to be blocking conductivity and are expected to impact the mechanical properties of the material. The defects are also observed in a yttrium-doped barium zirconate/cerate (BZCY) with nickel oxide and are shown to be prevalent in close-to-stoichiometric BZY ( A / B = 1.001), indicating that they are common defects for this material class.