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

• Published in: Surface science Vol. 666; pp. 1 - 8
• Main Authors: Kozakov, A.T., Polozhentsev, O.E., Raevski, I.P., Kumar, N., Raevskaya, S.I., Nikolskii, A.V.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.2017; Elsevier BV
• Subjects: Chemical compounds; Electron states; Electronic structure; Energy levels; Experiments; Ferroelectric materials; Ferroelectrics; Ferroelectric–relaxor; Mathematical analysis; PbSc1/2Nb1/2O3; Phase transition; Phase transitions; Single crystals; Single-crystal; Temperature dependence; Valence band; X-ray photoelectron spectra; Electronic structure; PbSc1/2Nb1/2O3; Single-crystal; X-ray photoelectron spectra; Ferroelectric–relaxor; Phase transition
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2017.08.014

•Permittivity-temperature dependence of PSN single crystal was measured in the frequency range of 10−2–104 Hz.•X-ray photoelectron spectroscopy (XPS) was used to study the elemental composition and electronic structure of PSN single crystal surface in the temperature range 297–673 K.•Electronic density of state calculation of PSN single crystal in the ferroelectric and paraelectric state was first carried out using self-consistent full multiple scattering of a photoelectron in a real space.•The XPS studies did not reveal any difference in electronic structure of PSN in the ferroelectric and paraelectric phases. This seems to be related to the spatial variation of the ordering degree of Sc and Nb in PSN single crystals studied.•Scribing of PSN single crystal surface leads to a formation of a surface phase with a smaller number of oxygen atoms around the lead ones as compared to the bulk. The temperatures of the ferroelectric phase transition in the bulk and in the near-surface part of PbSc1/2Nb1/2O3 (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. [Display omitted]