XAFS analysis of particle size effect on local structure in BaTiO₃

The local structure of several samples of BaTiO₃ prepared by solution-gelation method with different particle sizes has been investigated using XAFS. Although the macroscopic crystal structure changes from tetragonal to cubic at room temperature when the particle size is smaller than 100 nm, Raman and XAFS spectroscopy measurements obtain that Ti atoms are displaced from the center of cubic symmetry for all the samples studied. Results of both EXAFS and XANES measurements of the local structure around Ti atoms show that the magnitude of the Ti atom off-center displacement does not depend on the particle size.