Electronic structure of PbSc1/2Nb1/2O3 single-crystal ferroelectric-relaxor in the paraelectric and ferroelectric state

The temperatures of the ferroelectric phase transition in the bulk and in the near-surface part of PbSc 1/2 Nb 1/2 O 3 (PSN) single crystal were determined from the temperature dependence of dielectric permittivity measured at several frequencies. These temperatures differ by 12 K due to different degree of Sc and Nb ordering. X-ray photoelectron spectra of the Pb4f-, Pb5d-, Nb3d-, Sc2p-, O1s energy levels and valence band of PSN single crystal were studied by X-ray photoelectron microprobe ESCALAB 250 at several temperatures. Total and partial densities of electron states of PSN in the paraelectric and ferroelectric phases were calculated via the method of self-consistent full multiple photoelectron scattering in the real space, using the Feff9 code. Calculations have shown an increase in the intensity of Pb6s peak as a result of transition from ferroelectric to paraelectric state. The present calculation and the experiment have shown the absence of the energy shift of Pb6s states during the ferroelectric–paraelectric phase transition. Comparison of calculated and experimental results shows a close correspondence between them.