Effects of local atomic order on the pre-edge structure in the TiK x-ray absorption spectra of perovskite CaTi1-xZrxO3

[摘要] 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)(n)Ca8O24 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.

[发布日期] 2006-12-01

[关键词] SRTIO3;SPECTROSCOPY;CATIO3;ELNES