R dependence of electronic structure in perovskite type structure compounds, RBRh₃ (R: Sc, Y and La)

The electronic structures of perovskite type structure, RBRh₃ (R: Sc, Y and La) were studied by X-ray photoelectron spectroscopy and calculation with full potential linearized augmented plane wave (FLAPW) method. As the lattice constant of the crystals increases with the atomic number of R, it can be discussed how the bond length between boron and rhodium atoms effect on the bonding character. The valence band XPS profiles of the samples are well coincided with the calculated profiles. The calculated electron density maps of the valence bands indicate the following. The charge transfer directions are from R to rhodium atoms and from boron to rhodium atoms. The bonds of RRh and BRh atoms have also covalent character. The covalency of RRh bond increases with the order of the atomic number of R atoms. On the other hand, the covalent bond of BRh decreases with the order atomic number.