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Papers by Author: N.B. Ivanova

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The Influence of Ca Substitution on Magnetic and Electric Properties of GdCoO_{3- δ} Cobaltite

Authors: N.B. Ivanova, Juan Bartolomé, A. Figueroa, J. Blasco, Ana B. Arauzo, M.S. Platunov, V.V. Rudenko, N.V. Kazak

Abstract: The polycrystal samples of Gd1-xCaxCoO3-δ with different content of Ca were synthesized by three different techniques: solution method, solid state reaction and a sol-gel method. A study of magnetic and electric properties have been made. It is shown that the magnetic properties of this compound are in a high degree close to the same of the parent GdCoO3 with Co3+ ions being in a low spin state below the room temperature. The conductivity investigation revealed its increase by alkaline-earth substitution typical in rare-earth cobaltites.

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Conductivity Study of Co₃O₂BO₃ and Co_3-xFe_xO₂BO₃ Oxyborates

Authors: N.V. Kazak, N.B. Ivanova, V.V. Rudenko, S.G. Ovchinnikov, A.D. Vasil’ev, Yu.V. Knyazev

Abstract: Single crystals of cobalt oxyborates Co3O2BO3 and Co3-xFexO2BO3 were synthesized. The crystal structure and electric properties were investigated. The difference in the electrical resistivity behaviors was found. For parent Co3O2BO3 nor simple activation law, nor Mott variable range hopping (VRH) are acquirable to describe the experimental data in wide temperature region. In contrast for Co3-xFex O2BO3 Mott’s variable-range hopping conductivity clearly dominates.

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