Observation of Pt-atom complexes in CaTi1-xPtxO3-δ

The ‘intelligent catalyst’ concept, involving cyclical movement of precious metal atoms in and out of a perovskite oxide lattice, was proposed by Nishihata et al. in 2002, and the precious metal atom (Pd) was then believed to occupy the B site in the perovskite (LaFeO3) lattice, based on X-ray anomalous diffraction measurements [1]. Since then, B site occupancy has generally been assumed for all other cases in most theoretical and experimental studies [2-4]. In the present work, Pt-atom complexes, involving both B and A site occupancy, were observed in aberration-corrected (Cs-corrected) High-Angle Annular Dark-Field (HAADF) images of CaTi1-xPtxO3-δ, providing an unexpected example of precious metal bonding in this case.