X-ray photoelectron study of the valence state of iron in iron-containing single-crystal (BiFeO sub(3, PbFe) sub(1)/2Nb sub(1/2O) sub(3)), and ceramic (BaFe sub(1/2Nb) sub(1)/2O sub(3) multiferroics)

• Published in: Journal of electron spectroscopy and related phenomena 2011-02, Vol.184 (1-2), p.16-23
• Main Authors: Kozakov, A T, Kochur, A G, Googlev, KA, Nikolsky, A V, Raevski, I P, Smotrakov, V G, Yeremkin, V V
• Format: Article
• Language: eng ; fre ; ger
• Subjects: Approximation; Ceramics; Iron; Mathematical analysis; Photoelectrons; Single crystals; Spectra; X-ray photoelectron spectroscopy; X-rays
• ISSN: 0368-2048
• DOI: 10.1016/j.elspec.2010.10.004

Fe2p, Fe3p, and Fe3s X-ray photoelectron spectra (XPS) are measured with high resolution in single-crystal multiferroics BiFeO sub(3 and PbFe) sub(1)/2Nb sub(1/2O) sub(3), as well as in reference samples Fe sub(2O) sub(3), FeSO sub(4) super(.)7H sub(2O, FeC) sub(2)O sub(4) super(.)2H sub(2O. The spectra are assigned based on an isolated-ion approximation calculation. Single-crystal multiferroics and Fe) sub(2)O sub(3 are shown to have the Fe ions only in the Fe) super(3)+valence state. Ceramic samples of BaFe sub(1/2Nb) sub(1)/2O sub(3 with various relative Fe) super(2)+Fe super(3+) abundances are synthesized in various conditions. An approximate method to determine the Fe super(2+)/Fe super(3+) ratio in a sample is suggested. The method is based on the fitting of the sample's 2p XPS with a superposition of Fe super(2+) and Fe super(3+) 2p spectra. An effect of temperature regimes of sintering and annealing on the Fe super(2+)/Fe super(3+) ratio is demonstrated.