XPS on Nd0.6-Bi Sr0.4MnO3 nano powders

The structural and electronic properties on Nd0.6-xBixSr0.4MnO3 nano powders with x = 0, 0.05 and 0.1 are reported. The compounds were prepared using sol-gel combustion method. X-ray diffraction studies confirm that all samples crystallize in orthorhombic structure having Pnma space group. The powders consist of spherical particles that tend to agglomerate, with average grain sizes of about 40–50 nm. XPS measurements reveal a shift toward lower binding energies of Mn 3s, Mn 2p, Nd 3d, and O 1s core levels with increasing Bi content, which can be explained by the larger ‘c’ lattice parameter and therefore larger atomic distances. The analysis of the core level XPS spectra proves the existence of both Mn4+ and Mn3+ ions in all samples, as well as the localization of Bi3+ ions in the perovskite lattice. The XPS valence-band is dominated by extensively hybridized Nd 4f-O 2p states, with contributions from Mn 3d-O 2p bonding and Mn 3d states.