Effect of Zr4+ doping on the creep behavior of the oxygen transport membrane BaFeO3-d

Abstract

Aiming towards insight into the stability of newly developed advanced ceramic membrane materials, the time-dependent deformation at elevated temperatures is particularly important, where special consideration should be given to application-relevant atmospheres. This study examines the influence of Zr⁴⁺ doping on the creep behavior of BaFeO_3-δ in air and nitrogen atmospheres at temperatures between 700 ºC and 900°C under compressive stresses ranging from 20 MPa to 60 MPa. BaFeO_3-δ creep investigations revealed a transition from primarily diffusive to a combination of diffusive and dislocation-based mechanisms, owing to increasing oxygen deficiencies with increasing temperatures that culminate in a low to high symmetric crystal structure transition. Zr⁴⁺ doping improved the creep resistance and altered the creep mechanism to a predominantly dislocation-based mechanism, accompanied by a transition to a cubic crystal structure. Nitrogen atmospheres negatively affected the creep resistance of BaFeO_3-δ and BaFe_0.9Zr_0.1O_3-δ, increasing the creep deformation rates for all temperature and stress levels.