Valence State of Pb in Transition Metal Perovskites PbTMO₃ (TM = Ti, Ni) Determined From X-Ray Absorption Near-Edge Spectroscopy

We present a combined experimental and theoretical Pb-L₃ X-ray absorption near-edge spectroscopy (XANES) to investigate the chemical state of Pb in transition metal perovskites PbTMO₃ (TM = Ti, Ni). A pre-edge feature originated from the excitation of a 2p core electron to the 6s orbital is only observed in PbNiO₃, from which the valence of Pb is determined to be Pb⁴⁺ with two 6s holes. However, no such 2p–6s related excitation was observed in PbTiO₃, indicating the formation of Pb²⁺ with fully occupied 6s² state in this materials. Our results demonstrate that this pre-edge peak from dipole allowed 2p–6s transition is a sensitive finger-print of the Pb valence state in solid state materials.