Intrinsic magnetic properties of BixCo2−xMnO4 spinels obtained by short-time etching

Journal of Magnetism and Magnetic Materials Volume: 339 Pages: 157-162 Published: 2013

Scanning electron microscopy (SEM) images for Co2MnO4 and (a) Bi0.1Co1.9MnO4 before (b) and after etching (c). Circles in (b) enhance the presence of white spots identified as bismuth oxide impurities.

Writers: M.E. dos Santos; P.N.Lisboa-Filho; F.Gouttefangeas; O.Peña

Keywords: Multiferroics; Oxide spinel; Ferrimagnetism; Etching; pH

Abstract: We report the structural and magnetic properties of Co2MnO4, 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+–Mn4+ 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.

See PDF: Intrinsic magnetic properties of BixCo2−xMnO4 spinels obtained by short-time etching

DOI: 10.1016/j.jmmm.2013.02.047

Robson Lima
Sobre Robson Lima 87 Artigos
Atua no Centro de Desenvolvimento de Materiais Funcionais.