Magnetoelectric properties of BixCo2−xMnO4 (⩽x⩽0.3) (original) (raw)
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Investigation of the magnetic and the ferroelectric properties of BiMnO3 thin films
Journal of the Korean Physical Society, 2013
Various composites of nominal composition (1-x)Ba 0.95 Ca 0.05 TiO 3 + xLi 0.1 Cu 0.1 Co 0.1 Zn 0.6 Fe 2.1 O 4 have been prepared and studied thoroughly. X-ray diffraction and Rietveld refinement confirmed the presence of Ba 0.95 Ca 0.05 TiO 3 and Li 0.1 Cu 0.1 Co 0.1 Zn 0.6 Fe 2.1 O 4 phases in the composites. The microstructures have been investigated by field emission scanning electron microscopy. Temperature dependent dielectric constant shows two peaks, one is at 150°C and another at 270°C for x = 0.10 composite which resembles the characteristic ferroelectric and ferromagnetic transition peaks. A gradual progression of ferro-para electric transition towards room temperature is observed with doping. The non-Debye type dipole relaxations have been found. The linearity in the log(σ AC) vs. log(ω) plots indicate that conduction is due to small polaron hopping. The real part of initial permeability increases with growing ferrite concentration but the cutoff frequency decreases. The magnetic property is also enhanced with doping content. The typical ferroelectric hysteresis loops have also seen with the addition of Li 0.1 Cu 0.1 Co 0.1 Zn 0.6 Fe 2.1 O 4 up to x = 0.40. The impedance values are found to decreases in the Nyquist plots. The magnetoelectric voltage coefficient is obtained 287 × 10 3 V/mT for x = 0.15 at room temprrature. We found both ferromagnetic and ferroelectric hysteresis loops at room temperature. So, it confirms that the composites exhibit room temperature multiferroicity. This type of composites offers variety of opportunity for multifunctional devices application like hetero-structured read / write memory devices, switching devices and magnetic field sensing devices.
Journal of Magnetism and Magnetic Materials, 2017
Lead free magnetoelectric composites that comprise Co 0.6 Zn 0.4 Fe 1.7 Mn 0.3 O 4 (CZFMO) and Bi 1/2 Na 1/2 TiO 3 (BNT) were synthesized using sol-gel method and it's structural, dielectric, magnetic, ferroelectric and magnetoelectric (ME) properties were studied. The X-ray diffraction displayed the single phase formation of parent phases and the presence of two phases in the composites. The temperature dependent dielectric spectra of samples indicates two anomalies at~220°C and~320°C were ascribed to ferroelectric to antiferroelectric, and anti-ferroelectric to paraelectric phase transitions respectively. Room temperature (RT) magnetic measurements show that composites are soft magnetic. The composite with x=0.2, showed the large value of ME voltage coefficient (α E)~58 mV/cmOe. Moreover, these ME composites provide a great opportunity as potential lead free systems for multifunctional devices. 2. Experimental High purity bismuth nitrate [Bi(NO 3) 3 •5H 2 O], nickel nitrate Co(NO3)2.6H2O, iron nitrate [Fe(NO 3) 3 •9H 2 O], sodium carbonate
Increase of magnetic and magnetoelectric properties in Co/Mn co-doped BiFeO3 multiferroic
Journal of Magnetism and Magnetic Materials, 2019
Co and Mn co-doped BiFeO3 samples are successfully realized using a stirred hydrothermal route to form BiFe0.9CoxMn0.1-xO3 (for x=0.01, 0.03, 0.05, 0.07 and 0.09) system. Our data show that both the ferroelectric (TC) and antiferromagnetic (TN) transition temperatures increase especially TN varies by up to 23°C when changing from BiFe0.9Co0.01Mn0.09O3 to BiFe0.9Co0.09Mn0.01O3. Such strong TN enhancement is explained by Co ionic size which induces a chemical pressure by reducing the unit cell and consequently favor the exchange coupling between the magnetic moments carried by Fe/Co/Mn. Moreover, Co 3+ (d 6 electronic configuration) by replacing Fe (d 5) increases the magnetization reaching a value of 3.394 emu/g for BiFe0.9Co0.09Mn0.01O3, by favoring double exchange interactions. The direct magnetoelectric (ME) measurements on those samples show a significant increase of the ME coefficient with a value of 8.720 mV/(Oe.cm) for BiFe0.9Co0.05Mn0.05O3 i.e. up to 6 times higher than that of pure BiFeO3. For Mn-rich compositions, because of a parasitic Bi25FeO40 phase and high electric losses, no intrinsic ME coefficient could be measured.
Room temperature ferromagnetic and ferroelectric properties of Bi1−xCaxMnO3 thin films
AIP Advances, 2014
Bi 1-x Ca x MnO 3 (BCMO) thin films with x = 0, 0.1, 0.2, 0.3 and 0.4 are successfully deposited on the n-type Si (100) substrate at two different temperatures of 400 • C and 800 • C using RF magnetron sputtering. The stoichiometry of the films and oxidation state of the elements have been described by X-ray photoelectron spectroscopy analysis. Dielectric measurement depicts the insulating property of BCMO films. Magnetic and ferroelectric studies confirm the significant enhancement in spin orientation as well as electric polarization at room temperature due to incorporation of Ca 2+ ions into BiMnO 3 films. The BCMO (x = 0.2) film grown at 400 • C shows better magnetization (M sat) and polarization (P s) with the measured values of 869 emu / cc and 6.6 µ C / cm 2 respectively than the values of the other prepared films. Thus the realization of room temperature ferromagnetic and ferroelectric ordering in Ca 2+ ions substituted BMO films makes potentially interesting for spintronic device applications.
Study of ferromagnetic and ferroelectric properties of nanocrystalline Bi2Mn4O10
Applied Physics A
Nano-crystalline bismuth manganese oxide Bi2Mn4O10 was prepared from Bi2O3 and MnO2 by mechanochemical technique at different milling times followed by heat treatment at 1073 K. The crystal structural were obtained using X-ray diffraction (XRD) and TEM. We obtained the variation of the crystallite size and micro-strain with milling time. The magnetic parameters include the saturation magnetization, coercivity and squareness ratio were obtained by vibrating sample magnetometer (VSM). Each of the coercive field, Squareness ratio and saturation magnetization increased with increasing the milling time. The electrical conduction of the prepared samples was evaluated by AC conductivity measurements at different temperature, the dielectric parameters were plotted against temperature at different frequencies. The conduction mechanism is described by the correlated barrier hopping model (CBH). The recoverable energy density and loss energy was obtained to calculate the storage energy efficie...
BiFeO 3 is one of the few single-phase multiferroics, showing antiferromagnetic and ferroelectric ordering. Since the dielectric properties in the ceramic state of the pure BiFeO 3 were rather poor and in order to stabilize the perovskite state and to induce ferromagnetism at room temperature, it was adopted the strategy of doping with rare earth or forming solid solutions. Substituting Fe with Mn in BiFeO 3-based compounds is supposed cause better properties in terms of leakage current density and also to induce changes in the magnetic order of the system. In the present paper, the effect of Mn substitution on the dielectric and magnetic properties of the BiFe 1−x Mn x O 3 ceramics has been studied. Homogeneous samples from microstructural point of view were obtained for all the compositions analyzed. The magnetic properties are strongly affected by the presence of Mn ions. The possible origin of these behavior is discussed in terms of phase purity, grain size and grain boundary phenomena. The extrinsic properties are impossible to be fully controlled by normal ceramic processing. By controlling the extrinsic contributions to the dielectric properties, the ceramic system might be a valuable multiferroic material for magnetoelectric applications. At room temperature the ceramic is a multiferroic, since it is ferroelectric and magnetically-ordered.
Magnetic and Dielectric Studies on Cobalt Substituted BiFeO3
2015
This thesis presents the study of structural, surface morphology, electric, magnetic, magnetoelectric and magnetodielectric properties of Cobalt substituted multiferroic BiFeO3. Since their discovery, multiferroics have brought tremendous interest among the researchers due to the coexistence of various ferroic order parameters. The synchronization of the magnetic and electric order parameter, hence generating magnetoelectric coupling, has been of importance in particular. Various functional devices aiming at the coupling between the ferroelectric and ferromagnetic order parameter are underway. Among all, the perovskite oxides (ABO3) based multiferroics are of prime interest due to their ease of synthesis and easy to understand physical interactions due to their simple structure. Bismuth Ferrite (BiFeO3), is a prototype ABO3 type multiferroic material, possessing the ferroelectric Curie temperature (Tc) ~ 1103K and antiferromagnetic Neel temperature (TN) ~ 643K. It exhibits a weak ne...
Crystal structure, piezoelectric and magnetic properties of BiMn1-xFexO3 (x ≤ 0.4) solid solutions
Modern Electronic Materials
The crystal structure, piezoelectric and magnetic properties of BiMn1-xFexO3 (x ≤ 0.4) solid solutions synthesized using different solid state reactions from a stoichiometric mixture of simple oxides at high pressures and temperatures have been studied. The structure of the composition undergoes a concentration phase transition from the monoclinic to the orthorhombic structure. The formation of the orthorhombic phase is observed at the concentration x ≈ 0.2 and is accompanied by the destruction of the dz2 orbitals of the Mn3+ ions causing the stabilization of a homogeneous magnetic state. The solid solutions containing 0.2 ≤ x ≤ 0.4 exhibit a non-zero piezoresponse and may have ferroelectric or magnetic domain structures, the ferroelectric switching voltage decreasing with an increase in the iron concentration while the remanent magnetization decreases. The highest piezoresponse signal is observed for the BiMn0.7Fe0.3O3 solid solution. The relationship between the chemical compositi...
Communications in Physics
The crystal structure, phonon vibration, microstructure, and magnetic properties have been investigated in multiferroics Bi0.9Sm0.1Fe1-xMnxO3 for x = 0.02 – 0.1. The structural analysis by XRD and Rietveld refinement suggest that Mn doping compounds crystallize in the polar R3c rhombohedral symmetry (isostructural with BiFeO3). Raman analysis confirms no structural transformation but the change of line widths and peak intensities reveal the lattice distortion in Mn-substitution samples. The study of microstructure shows no obvious change of grain size and shape. The magnetic properties of the as-prepared samples show the linear magnetic field dependence of magnetization, suggesting the antiferromagnetic feature of polycrystalline ceramics. The field dependence of magnetization measured after two-years synthesis and after applying an electric field reveal a decrease of maximum magnetization but the hysteresis loops retain the antiferromagnetic behavior. The implication of these resul...