On the Anomalous Magnetic Behavior and the Multiferroic Properties in BiMn₂O₅

Abstract

Sealed-tube synthesis of BiMn2O5 materials and their physical properties have rationally been reinvestigated depending on the reactants. The aim of the study was to characterize its potential multiferroic properties and to investigate the anomalous magnetic properties in relation to the expected ferroelectric properties. Rietveld refinement of the room temperature X-ray diffraction data shows the stability of the crystallographic structure with a Mn(3+)/Mn(4+) ratio far from 1 because of bismuth and oxygen deficiencies despite the sealed-tube synthesis. Our detailed magnetic susceptibility and specific heat data analysis unambiguously support an intrinsic anomalous magnetic behavior in relation to the establishment of a magnetic short-range ordering far from the Néel temperature. Around room temperature, oxygen vacancies are responsible for supporting the dielectric loss peak measured, and, interestingly, the so-called T*, which was underlined in relation to an anomalous phonon shift (García-Flores, A. F.; et al. Phys. Rev. B 2006, 73, 104411), is not a characteristic temperature in relation to the multiferroic properties because no ferroelectric transition was detected.

Electric relaxation and Mn3+/Mn4+ charge transfer in Fe-doped Bi12MnO20–BiMn2O5 structural self-composite

“…The antiferromagnetic transition at T Néel = 110 K for BiMnO 3 [44] and ferromagnetic cluster-like behaviour below T C = 100-110 K for Fe-doped BiMnO 3 [8,33] have been reported for these materials, which have shown perovskite symmetry and composition. The antiferromagnetic order below T Néel = 40 K has been reported for BiMn 2 O 5 polycrystalline samples [10]. The ceramics obtained from NaNbO 3 mixed with the Bi 12 MnO 20 -BiMn 2 O 5 compound also exhibited magnetic ordering below 40 K, most probably related to the BiMn 2 O 5 phase contribution [45].…”

“…For instance, pure submicron BiMn 2 O 5 particles have been obtained by means of hydrothermal method [9]. BiMn 2 O 5 shows antiferromagnetic order below T Néel * 40 K [9][10][11].…”

Electrochemical supercapacitor based on multiferroic BiMn 2 O 5

“…BiMn 2 O 5 has an orthorhombic structure with ordered Mn 4þ and Mn 3þ ions. The Mn 4þ ions are located in [Mn 4þ O 6 ] octahedra [30], which share ages and form a linear chain along the c-axis. The octahedra are interconnected by [Mn 3þ O 5 ] square pyramids, containing Mn 3þ ions [30].…”

“…The Mn 4þ ions are located in [Mn 4þ O 6 ] octahedra [30], which share ages and form a linear chain along the c-axis. The octahedra are interconnected by [Mn 3þ O 5 ] square pyramids, containing Mn 3þ ions [30]. The 6s 2 electrons of the highly polarizable Bi 3þ cations contribute to the large distortion of the [BiO 8 ] polyhedrons [30] and favor the formation of ferroelectric ordering [31] in BiMn 2 O 5 in the direction of b-axis below the antiferromagnetic Neel temperature T N ¼ 40 K. Moreover, BiMn 2 O 5 exhibits interesting properties at higher temperatures, which are not well understood.…”

“…The octahedra are interconnected by [Mn 3þ O 5 ] square pyramids, containing Mn 3þ ions [30]. The 6s 2 electrons of the highly polarizable Bi 3þ cations contribute to the large distortion of the [BiO 8 ] polyhedrons [30] and favor the formation of ferroelectric ordering [31] in BiMn 2 O 5 in the direction of b-axis below the antiferromagnetic Neel temperature T N ¼ 40 K. Moreover, BiMn 2 O 5 exhibits interesting properties at higher temperatures, which are not well understood. In the previous investigation [32] we discovered a pyroelectric effect in the range of 77e500 K in the a-axis direction of BiMn 2 O 5 monocrystals.…”