Electronic structure of the R2Ti2O7 (R = Sm-Er, Yb, Lu) oxides -: art. no. 075106

We present the results of the electronic structure investigation for the compounds R2Ti2O7 (R = Sm-Er, Yb, Lu) with the pyrochlore-type crystal structure. The methods of x-ray photoelectron and emission spectroscopies, as well as the first-principles band-structure calculations have been employed. A good agreement between theoretical and experimental results was observed. We found considerable influence of the R 5p - O 2s interaction on the formation of the subvalent bands that has to be taken into account while interpreting experimental data. Estimated values of the optical gaps are closely related to the degree of TiO6 octahedron distortion.