Effects of Nonstoichiometry and Plastic Deformation on Charge and Spin States of Cobalt Ions in LnBaCo2BaO5.5 – δ (Ln = Tb, Eu): Soft X-ray Absorption Spectroscopy Studies


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Abstract

We present results of soft X-ray absorption spectroscopy studies of nonstoichiometric Tb1 ‒ yBa1 +yCo2 –xO5.5 – δ cobaltites and EuBaCo2O5.5 cobaltite powders subjected to mechanical impact (milling in a ball mill). It was established that in octahedra of Tb1 – yBa1 + yCo2 – xO5.5 – δ cobaltates Co3+ ions are in the high spin state. In EuBaCo2O5.5 powder after milling in a ball mill, a surface area (5–10 nm) of particles was found to be decomposed into Co3O4, BaCO3, and EuCoO3 phase components. A knowledge of the low-spin state of Co3+ ions in EuCoO3 and Co3O4 and possibilities of surface-sensitive soft X-ray absorption spectroscopy have allowed to determine the composition of the EuBaCo2O5.5 sample (subjected to ball milling) near its surface, which is inaccessible to standard X-ray phase analysis.

About the authors

V. R. Galakhov

Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences; Ural State Mining University

Email: gizhevskii@imp.uran.ru
Russian Federation, Ekaterinburg, 620108; Ekaterinburg, 620137

B. A. Gizhevskii

Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences

Author for correspondence.
Email: gizhevskii@imp.uran.ru
Russian Federation, Ekaterinburg, 620108

S. V. Naumov

Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences

Email: gizhevskii@imp.uran.ru
Russian Federation, Ekaterinburg, 620108

M. S. Udintseva

Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences

Email: gizhevskii@imp.uran.ru
Russian Federation, Ekaterinburg, 620108

V. V. Mesilov

Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences

Email: gizhevskii@imp.uran.ru
Russian Federation, Ekaterinburg, 620108

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