Effects of Local Atomic Order on the Pre-Edge Structure in the Ti K X-Ray Absorption Spectra of Perovskite CaTi1-xZrxO3

TL;DR

This study investigates how local atomic arrangements and tilting affect the pre-edge features in Ti K-edge X-ray absorption spectra of CaTi1-xZrxO3, revealing that pre-edge intensities reflect local B-site order.

Contribution

It combines experimental spectra with multiple-scattering calculations to link pre-edge features to local atomic order in perovskite solid solutions, providing a new spectroscopic method for assessing B-site distribution.

Findings

Pre-edge peak intensities vary systematically with Zr content.

Calculations show pre-edge features depend on Zr proximity to Ti.

Pre-edge intensities can quantify local B-site order.

Abstract

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.