Valence state of the manganese ions in mixed-valence La1−αBiβMn1+δO3±γ ceramics by Mn 2p and Mn 3s X-ray photoelectron spectra

• DOI: 10.1016/j.elspec.2012.06.017
• Publication Date: 2012-07-07T09:46:41Z
• Authors: A.G. Kochur; A.T. Kozakov; A.V. Nikolskii; K.A. Googlev; A.V. Pavlenko; I.A. Verbenko; L.A. Reznichenko; T.I. Krasnenko
• Keywords: Valency; Orthorhombic crystal system; Valence electron

Abstract Valence state of Mn in La 1− α Bi β Mn 1+ δ O 3± γ (LBMO) ceramic samples and in orthorhombic manganates RMn 2 O 5 (R = Y, Bi, Eu, Gd), is studied using Mn 2p- and Mn 3s-spectra. Both Mn 3+ and Mn 4+ ions are shown to be present in those compounds. Relative Mn 3+ /Mn 4+ ions contents are determined by fitting experimental Mn 2p-spectra with weighted superpositions of theoretical spectra of Mn 3+ and Mn 4+ ions calculated in one-configuration Pauli–Fock approximation considering thermal excitations in initial state. Content of the Mn 4+ ions correlates with the deviation δ in La 1− α Bi β Mn 1+ δ O 3± γ from stoichiometry, La 1− x Bi x MnO 3 . Separation of low-spin and high-spin components of Mn 3s-spectrum can be sensible to the relative content of Mn 3+ and Mn 4+ ions. Mn 3+ /Mn 4+ ratios derived from Mn 2p- and from Mn 3s-spectra compare well in the case of the RMn 2 O 5 manganates, while in the case of the LBMO ceramics the results obtained from the Mn 3s spectra are physically meaningless. Due to a complex interplay between 3d-electrons delocalization and strong many-electron effects the 3s spectra of 3d-elements may be misleading.