Effects of Local Atomic Order on the Pre-Edge Structure in the Ti K   X-Ray Absorption Spectra of Perovskite CaTi1-xZrxO3
  The effects of local B-cation (Ti, Zr) distribution and octahedral tilting on the pre-edge structure in the Ti X-ray absorption K-spectra of the CaTi1-xZrxO3 perovskite solid solutions were investigated. Experimental spectra for the disordered CaTi1-xZrxO3 samples revealed systematic variations of the pre-edge peak intensities with the x-values. Multiple-scattering calculations using 75-atom clusters Ti(TiO6)6-n(ZrO6)nCa8O24 were conducted to interpret these differences. The origin of the lowest unoccupied states in the conduction band of the CaTi1-xZrxO3 was determined from the analyses of X-ray absorption near-edge structure of the O K-edge. The calculations reproduced the experimental spectra and demonstrated that the differences in the intensities of certain pre-edge feature are dominated by the probability of finding a Zr atom in the first B-cation coordination sphere around the absorbing Ti. The pre-edge structure appeared to be sensitive to small changes in the value of this probability, so that the pre-edge intensities could be used effectively to compare the extent of local B-site order in perovskite solid solution samples having similar chemical composition but processed differently. 
V. Krayzman, I. Levin, J. C. Woicik, D. Yoder, D. A. Fischer (Ceramics   Division, National Institute of Standards and Techn...