The electronic structure of the Ln2Ti2O7 oxides with pyrochlore type structure

The objects of investigation were pyrochlore type Ln(2)Ti(2)O(7) oxides (Ln = Sm - Lu) and ferroelectric La2Ti2O7 with layered perovskite-like structure. X-ray OK alpha, TiK beta(5), K alpha(1,2), Let-emission spectra and X-ray photoelectron spectra of the valence and core states were obtained for pyrochlore oxides. For Ln(2)Ti(2)O(7) X-ray photoelectron spectra have been measured. The cluster (X alpha-Scattering Waves) and band structure calculations (LMTO-ASA) have been carried out to study valence band structure and the charge states of atoms. As a result the valence band (VB) parameters of the Ln(2)Ti(2)O(7) series were defined. The Ln atomic number (Z(Ln)) influence on the Ln(2)Ti(2)O(7) (Ln=La; Sm-Lu) electronic structure was disclosed. The atomic charge states and their dependence on Z(Ln) have been determined in mentioned oxides. The Ln(2)Ti(2)O(7) electronic structure genesis has been defined.