Intrinsic magnetic properties of BixCo2-xMnO 4 spinels obtained by short-time etching
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2013-08-01
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We report the structural and magnetic properties of Co2MnO 4, partially substituted by Bi at the octahedral site. Bismuth enhances ferromagnetism due to a decrease of the Co2+-Co2+ antiferromagnetic interactions and an increase of the Mn3+-Mn 4+ exchanges. Spurious phases (magnetic and/or nonmagnetic oxides) can easily form because of the large differences between the ionic radii of Bi3+ and Co3+, hiding or altering the intrinsic physical properties of the main BixCo2-xMnO4 phase. An easy way to eliminate the secondary phases is using acid reagents. Short-time etching of Bi0.1Co1.9MnO4 using nitric acid was successfully used, keeping most of the properties of the initial compound, with no alteration of the crystallographic structure. Final stoichiometry was respected (∼Bi0.08Co1.82MnO4), meaning that the material after etching definitely contains bismuth elements in its structure and the observed properties are intrinsic to the oxide spinel. Additional experiments were performed as a function of the synthesis conditions, showing that an optimal pH value of 7 allowed the best magnetic response of the non-doped material. © 2013 Elsevier B.V. All rights reserved.
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Etching , Ferrimagnetism , Multiferroics , Oxide spinel , pH , Additional experiments , Antiferro-magnetic interactions , Crystallographic structure , Magnetic response , Oxide spinels , Structural and magnetic properties , Synthesis conditions , Bismuth , Bismuth compounds , Carbon dioxide , Magnetic properties , Manganese , Manganese oxide , Stoichiometry , Cobalt compounds
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Journal of Magnetism and Magnetic Materials, v. 339, p. 157-162.