Crystal Structure Refinement of the A-Site-Ordered Double-Perovskite Oxide PrBaCo₂O_6−δ

Abstract

Crystal structures of double perovskite cobalt oxide PrBaCo₂O_6−δ with a wide range of oxygen deficiency content δ (0 ≤ δ ≤ 0.85) have been analyzed by using Rietveld refinement of synchrotron X-ray powder diffraction data. The bond valence sum calculation indicates a monotonic reduction in Co valence with increasing δ. The atomic position of Co ion shifts toward the apical oxygen with whole occupation with increasing δ, together with the gradual decrease in the occupancy for the opposite apical oxygen with partial deficiency. This finding indicates that the local structure around Co ions as catalytically active sites is significantly varied by oxygen deficiency.