X-ray photoelectron diffraction of ABO(3)-type perovskites: site determination for dopants

Abstract

We present a set of polar-angle-dependent X-ray photoelectron spectra (XPS) obtained from in-situ-cleaved KNbO3. The angle-dependent variation of intensity can be explained by the diffraction of the photoemitted electron by the surrounding atoms. This anisotropy in intensity may be used to determine the lattice site of the emitting atom. Measurements were carried out on KTa1-xNbxO3 single crystals (x = 0.92). In spite of the low concentration of Ta, the atomic position of this element could be deduced from a comparison of the angle-dependent spectra, giving a hint that both tantalum and niobium occupy the same lattice site. Angle-dependent measurements were carried out on Ba0.77Ca0.23TiO3 single crystals in order to determine the atomic position of the calcium atoms. Extended comparison of the measurements leads to the assumption that calcium is located on the barium site only. (C) 1998 Elsevier Science B.V. All rights reserved.