Electronic structure of AgNbO3 and NaNbO3 studied by X-ray photoelectron spectroscopy

The XPS examinations of the AgNbO3 and NaNbO3 single crystals and ceramics allowed estimate their average composition as Ag1.1Nb0.9O3 and Na1.2Nb0.9O2.9. The valence bands of the AgNbO3 compound, formed mainly of the Nb 4d, Ag 4d and O 2p states, show an energy gap about 3 eV while for the NaNbO3 compound consist of the O 2p states hybridized with the Nb 3d states and show an energy gap about 4 eV. The chemical shifts of these compounds suggest a mixed ionic and covalent character of the bonds. The broadening of the core level lines of AgNbO3 suggests a stronger structural disorder in comparison with NaNbO3 compound.