Multiferroic BiMnO3 Research Articles

Photocatalytic degradation of rhodamine B using BiMnO3 nanoparticles under UV and visible light irradiation

Rhodamine B (RhB), a toxic dye is environmentally hazardous and harmful to living organisms, which is primarily used in various industries. Multiferroic BiMnO3 (BMO) with (BMO 1) and without (BMO 2) surfactant (CTAB) was synthesized using hydrothermal method, which acts as a photocatalyst for the Rhodamine B dye degradation process. BMO had tested as a photocatalyst for dye degradation of Rhodamine B dye in UV and Visible light irradiation due to its narrow bandgap. On performing various structural and optical characterizations, the structure of as-prepared BMO samples confirmed, and their crystallite size and bandgap were compared for with and without CTAB treated BMO samples. Under UV irradiation, the decomposition of RhB efficiency and decay time had been calculated as 68% and 75 min for BMO 1. In H2O2 assisted visible light irradiation, BMO 2 shows better performance (90% and 55 min).

Study the surface effect on BiMnO3 multiferroic thin film by using Landau theory

Landau formalism is used to investigate the surface effect of multiferroic BiMnO3. This multiferroics have a polarization and magnetization below magnetic transition temperature. Magnetic extrapolation length parameter Δm and electric extrapolation length parameter δp express the surface effect in Landau free energy. These two parameters control the magnetic transition temperature, where δp control the ferroelectric transition temperature. The values of magnetization and polarization are reduced by decreasing the values of these surface parameters. Electric and magnetic susceptibilities are calculated. Stepwise behavior of electric susceptibility at magnetic transition temperatures is expressed. The values of susceptibilities for the films are lesser than that of the bulk due to surface effect coming from magnetism and ferroelectricity of multiferroics.

Effect of magnetic and electric fields on electrical and magnetic properties of multiferroic BiMnO3 films

The effect of magnetic and electric fields on the electrical and magnetic properties of BiMnO3 films within the framework of Landau-Ginzburg theory had been investigated. We also calculated and discussed the hysteresis loops of polarization and magnetization as a function of electric and magnetic fields. The results reveal that, the possibility of electric-field control of magnetization switching, and vice versa. By decreasing the film thickness of BiMnO3 film, it is shown that the coercive fields and remnant order parameters are suppressed.

Electron Transport Behavior of Multiferroic Perovskite BiMnO3 Prepared by Co-Precipitation Method**Supported by the Key Research Project of Shaanxi University of Science and Technology under Grant Nos 2016GBJ-12 and 2016BJ-59.

Perovskite BiMnO3 samples are successfully synthesized by the co-precipitation method at relatively low pressure and moderate temperature. The temperature dependences of resistivity are measured and systematically investigated. It is shown that the electrical resistivity increases sharply with the decrease of temperature above 210K and the fitted results demonstrate that the thermally activated conduction model is the dominant conduction mechanism for the electron transport behaviors in this temperature region. A dual conducting mechanism, i.e., the variable range hopping and thermal activated conduction, is suggested to be responsible for the transport behaviors of BiMnO3 in the region of 180–200 K. Moreover, the resistivity increases slightly with the decrease of temperature below 180K and the transport is governed by the variable range hopping mechanism.

Theoretical study on magnetoelectric effect in multiferroic tetragonal BiMnO3

Perovskite BiMnO3 with ferroelectric and ferromagnetic ordering simultaneously, as a kind of multiferroics, can be expected to have the coupling between the magnetic and dielectric properties as well as their control by the application of electric fields. This advantage can make BiMnO3 a good candidate for an artificial synapse material. Under the framework of the density functional theory, in this paper we adopt the generalized gradient approximation (GGA+U) plane wave pseudopotential method to calculate the ferroelectricity double-well potential curves and magnetic moments of Mn of tetragonal BiMnO3, with 0.18% and 4% strain exerted in its x-y plane. The results show that the magnetic moment of Mn monotonically increases from paraelectric state to ferroelectric state. It means that the ferromagnetic property of tetragonal BiMnO3 can be controlled by the intensity of polarization. The greater the stress, the greater the range of magnetic moment is. This would imply that the multiferroic artificial synapse device based on BiMnO3 can bring another degree of freedom into designing the complex cognitive systems of artificial intelligence in the future.

Retraction: Light-controlled resistive switching memory of multiferroic BiMnO3 nanowire arrays.

Retraction of 'Light-controlled resistive switching memory of multiferroic BiMnO3 nanowire arrays' by Bai Sun and Chang Ming Li, Phys. Chem. Chem. Phys., 2015, 17, 6718-6721.

The magnetic and multiferroic properties in BiMnO3

In this paper, the magnetic and multiferroic properties in the multiferroic material BiMnO3 are studied. A Heisenberg type Hamiltonian for BiMnO3 is proposed, in which the nearest and farther neighbors are considered. Thermodynamic quantities such as magnetization and magnetic susceptibility for different magnetic orderings under high pressure or magnetic field are calculated, and the simulation results fit the experimental results. Farther neighboring exchanges can result in the coexistence of the ferromagnetic ordering and certain antiferromagnetic ordering with no centrosymmetry. Our study demonstrates that the BiMnO3 should be the type-II multiferroic, and the ferromagnetic and ferroelectric orderings could coexist. The magnetic field control of ferroelectric polarization is also studied. The ferroelectric polarization is always suppressed by the external magnetic field.

Local crystal structure of multiferroic BiMnO3 studied by 57Fe probe Mössbauer spectroscopy

This paper presents a 57Fe probe Mossbauer spectroscopy study of a BiMn0.9657Fe0.04O3 manganite synthesized at high pressure (6 GPa). The BiMnO3 manganite possesses multiferroic properties and exhibits cooperative orbital ordering due to Jahn–Teller active Mn3+ ions. 57Fe Mossbauer spectra have been measured and analyzed in a wide temperature range, which includes the orbital ordering temperature of BiMnO3.

Influence of substrate and Ca substitution on multiferroic BiMnO3 thin films

BiMnO3 (BMO) and Ca (10 at%) substituted BiMnO3 (BCMO) thin films are grown on n-type Si (100) and Pt/Ti/SiO2/Si (100) substrates by RF magnetron sputtering. The structural, elemental, morphological, magnetic, dielectric and ferroelectric properties of the films are investigated by X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDAX), atomic force microscope (AFM), vibrating sample magnetometer (VSM), dielectric and ferroelectric measurements, respectively. The XRD pattern shows that the films acquire monoclinic structure with C2 space group. The elemental composition and surface roughness of the films are also measured by EDAX and AFM analysis, respectively. The VSM results exhibit that all the films possess room temperature ferromagnetism and the BCMO film deposited on the Si substrate has better magnetic properties (M rem = 1.8 × 10−3 emu cm−3) than the other films. The dielectric measurement also reveals that the BCMO film has the highest value of dielectric constant (497) with less dielectric loss (0.3). Similarly, the ferroelectric measurement implies that all the films possess room temperature ferroelectricity.

Orientational strain modulation of ferroelectric polarization in multiferroic BiMnO3

We report on the coupling of ferroelectric polarization to externally applied strains in multiferroic BiMnO3. Strains of less than 0.006% increased the remanent polarization by as much as 50% and are shown to depend on the orientation of the uniaxially applied external strain. Using multiple electrode arrays, we rule out the strain-induced rotation of the polarization vector, and confirm the magnitude of the polarization is increasing. Finally, a dielectric characterization determined that the onset of the strain coupling coincides with the relaxor ferroelectric freezing temperature.

ChemInform Abstract: One‐Step Bulk Synthesis of Stable, Near Unit‐Cell Sized Oxide Nanoparticles and Nanoparticle Blends Using KO2.

AbstractBulk quantities of nm‐sized oxides or hydroxides of Mg, Y, Ti, Mn, Fe, Co, Ni, Cu, Zn, Sn, Tl, Pb, and Ce, and nanoparticulate blends of the lithium cathode material LiCoO2, the multiferroic compound BiMnO3+δ, and the superconducting YBa2Cu3O7‐γ are prepared from aqueous solutions of sulfates, chlorides, acetates, or nitrates and a 2‐fold molar excess of KO2 (pH 7, <90% yields).

Jahn-Teller, Polarity, and Insulator-to-Metal Transition in BiMnO3at High Pressure

The interaction of coexisting structural instabilities in multiferroic materials gives rise to intriguing coupling phenomena and extraordinarily rich phase diagrams, both in bulk materials and strained thin films. Here we investigate the multiferroic BiMnO3 with its peculiar 6s2 electrons and four interacting mechanisms: electric polarity, octahedra tilts, magnetism, and cooperative Jahn-Teller distortion. We have probed structural transitions under high pressure by synchrotron x-ray diffraction and Raman spectroscopy up to 60GPa. We show that BiMnO3 displays under pressure a rich sequence of five phases with a great variety of structures and properties, including a metallic phase above 53GPa and, between 37 and 53GPa, a strongly elongated monoclinic phase that allows ferroelectricity, which contradicts the traditional expectation that ferroelectricity vanishes under pressure. Between 7 and 37GPa, the Pnma structure remains remarkably stable but shows a reduction of the Jahn-Teller distortion in a way that differs from the behavior observed in the archetypal orthorhombic Jahn-Teller distorted perovskite LaMnO3.

Structural polymorphism in multiferroic BiMnO3 at high pressures and temperatures

Structural phase transitions in BiMnO3 were studied by means of energy-dispersive X-ray diffraction in the pressure 0–4 GPa and temperature 300–900 K ranges, and also by means of angle-dispersive X-ray diffraction and Raman spectroscopy at high pressures up to 50 GPa and ambient temperature. The P–T phase diagram of BiMnO3 was constructed. A suppression of the transition temperatures between monoclinic C2/c and orthorhombic Pnma phases was observed under pressure. The temperature and pressure dependencies of lattice parameters were obtained. A new orthorhombic Imma phase was observed at P > 20 GPa. The lattice dynamics calculations were performed for the analysis of the Raman spectra of BiMnO3.

Evidence of Variable Range Hopping (VRH) and Exchange Interaction in Co-Doped Multiferroic BiMnO3 Nanoparticles

Among ABO3-type oxides, centrosymmetric (C2/c) BiMnO3 is one of the few single-phase multiferroics, with a highly distorted perovskite structure that has been extensively studied. In this work, to stabilize the crystal structure, to control temperature dependence of electrical properties and to induce low coercivity at low temperature, strategy of doping transition metal has been adopted for useful applications. Well-crystallized single-phase cobalt-doped bismuth manganite nanoparticles having general formula BiCo x Mn1−x O3 (x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were synthesized by co-precipitation method. All compositions show that substituting Mn with Co, in BiMnO3-based compounds enhances better and more stable structural properties, like lattice parameters and crystallite size, phase transition temperatures, temperature-dependent DC electrical properties and magnetic properties. The extrinsic contribution to the temperature-dependent electrical properties is an increased resistivity due to charge localization. The magnetic properties due to transition metal doping are strongly affected by the super-exchange interaction phenomenon between Co3+ and Mn4+ cations.

Specific features of magnetic structure formation in orbitally degenerate BiMnO3 manganite

The orbital structure and magnetic ordering of the Jahn-Teller multiferroic BiMnO3 manganite have been theoretically studied. It is shown that the orbital structure depends not only on the nearest-neighbor oxygen environment of manganese ions, but also on their next-to-nearest neighbors. The orbital structure significantly influences the magnetic order that forms as a result of competition between ferromagnetic and antiferromagnetic exchange interactions.

Evidence of the Griffiths phase in multiferroic BiMnO3 and BiFe0.5Mn0.5O3 films

Microstructure and magnetic properties of BiMnO3 and BiFe0.5Mn0.5O3 films, prepared by rf magnetron sputtering on LaAlO3 (001) single-crystalline substrate, are investigated. The selected-area electron diffraction analysis allows us to identify the crystal structure of the BiMnO3 film as orthorhombic, while the BiFe0.5Mn0.5O3 film has a hexagonal lattice symmetry. High-resolution electron microscopy study reveals the presence of strip-domain phase with a periodic spacing of about 3c in both films. Magnetic measurements show that in addition to the basic paramagnetic phase the films exhibit Griffiths phase behavior in a wide temperature range. We argue that the observed weak ferromagnetism is due to the strip-domain layered inclusions, rather than intrinsic physical origin of the films.

Local distortions in multiferroic BiMnO3 as a function of doping

The structure of doped BiMnO3 was studied using synchrotron x-ray powder diffraction. The dopants included isovalent magnetic and non-magnetic ions in the magnetic Mn sublattice (BiMn1−xMxO3 with M=Cr, Fe and Ga), isovalent ions in the Bi sublattice (Bi0.9La0.1MnO3) and isovalent self-dopants (Bi0.95MnO2.925). The results indicate that at low doping levels, the orbitally ordered structure (C2/c(I)) of BiMnO3 persists with strong Jahn–Teller distortions of two Mn1O6 and Mn2O6 octahedra (e.g. in BiMn0.95Ga0.05O3 and Bi0.95MnO2.925); the distortion parameters of the Mn1O6 and Mn2O6 octahedra are noticeably smaller in BiMn0.95Ga0.05O3 and Bi0.95MnO2.925 than in BiMnO3. At higher doping levels, the orbitally disordered structure (C2/c(II)) of BiMnO3 is realized with almost identical Mn–O bond lengths for one of the Mn1O6 or Mn2O6 octahedra (e.g. in BiMn0.85Cr0.15O3 and BiMn0.85Fe0.15O3). BiMn0.85Fe0.15O3 shows some anomalies in the distortion of the MnO6 octahedra and in the magnetic properties. Rather strong Jahn–Teller distortions were found for both the Mn1O6 and Mn2O6 octahedra in Bi0.9La0.1MnO3. The Mn1O6 and Mn2O6 octahedra were compressed along one direction in Bi0.9La0.1MnO3 whereas the octahedra were elongated in BiMnO3. Magnetic measurements indicate that Bi0.9La0.1MnO3 adopts the orbitally disordered C2/c(II) structure. The orbitally ordered state of BiMnO3 was found to be very fragile to any type of doping. However, as long as the orbitally ordered phase persists, the ferromagnetic transition temperature remains almost the same.

Growth and characterization of multiferroic BiMnO3 thin films

We have grown epitaxial thin films of multiferroic BiMnO3 using pulsed laser deposition. The films were grown on SrTiO3 001 substrates by ablating a Bi-rich target. Using x-ray diffraction, we confirmed that the films were epitaxial and the stoichiometry of the films was confirmed using Auger electron spectroscopy. The films have a ferromagnetic Curie temperature (TC) of 85 ± 5 K and a saturation magnetization of 1 μB/Mn. The electric polarization as a function of electric field (P-E) was measured using an interdigital capacitance geometry. The P-E plot shows a clear hysteresis that confirms the multiferroic nature of the thin films.

Synthesis and Magnetic Property of Multiferroic BiMnO3 Nanoparticles in the Pores of Mesoporous Silica

The mesoporous silica material SBA-15 was prepared with control pore size for use as a nanoparticle synthesis template. The X-ray diffraction results show that the nanopores were ordered in a hexagonal structure. The pore size was controlled by the synthesis conditions. Nanoparticles of the multiferroic compound BiMnO3 with an average size of about 14 nm were successfully synthesized in the pores of SBA-15, and their magnetic properties were investigated. The prepared BiMnO3 nanoparticles showed both antiferromagnetic and ferromagnetic behavior, whereas BiMnO3 bulk crystals consistently showed ferromagnetic behavior. The prepared BiMnO3 nanoparticles exhibited unique magnetic size effects: the appearance of antiferromagnetic behavior and the coexistence of antiferromagnetic and ferromagnetic components.

Single crystal growth of BiMnO3 under high pressure–high temperature

In the literature, the properties of the multiferroic BiMnO3 oxide have been studied in polycrystalline and thin film materials. Here, we report the first study performed on a single crystal of BiMnO3. The single crystals were grown at high pressure–high temperature (HP–HT) in a belt system using a flux method based on H3BO3. For the first time, we have measured the Raman spectrum of BiMnO3 and solved its crystallographic structure based on the data collected by X-ray diffraction (XRD) on a single crystal. In addition, we have studied in situ the HP–HT synthesis of polycrystalline BiMnO3 by XRD. Starting from a mixture of Bi2O3 and Mn2O3, an intermediate phase has been found before the formation of the distorted perovskite BiMnO3.