Effect of the Ca content on the electronic structure of Pb1-xCaxTiO3 perovskites

This study performs O K- and Ti L-3,L-2-edge x-ray absorption near-edge structure (XANES) measurements and first-principles pseudopotential calculations for the electronic structures of ABO(3)-type Pb1-xCaxTiO3 (x=0-1) perovskites. The features in the O K-edge XANES spectra are found to be contributed primarily by hybridization between O 2p and Ti 3d, Pb 6p, and Ca 3d orbitals. The O K-edge XANES spectra reveal that partial substitution of A cations, Pb, by Ca not only decreases O 2p-Pb 6p but also O 2p-Ti 3d hybridization. The Ti L-3,L-2-edge measurements find that the off-center displacement of Ti, and hence, ferroelectricity persist up to a Ca concentration between 0.3 and 0.4. (C) 2003 American Institute of Physics.