  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.
