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Synthesis of Bismuth Ferrite BiFeO <sub/>3</sub> by solution combustion method
摘要： In this work we describe the synthesis of bismuth ferrite BiFeO3 (BFO) by the method of combustion in solution. Using the techniques of X-ray diffraction (XRD) together with its refinement Rietveld reveals the existence of a distorted rhombohedral perovskite structure (Space group-R3c). The average size of the BFO crystallite was estimated from the half-height width of the X-ray diffraction peaks using the Scherrer’s equation. The morphology of the prepared sample was determined by scanning electron microscopy (SEM) and stoichiometry ratio of BFO was determined by energy dispersive spectroscopy (EDS)
关键词： BFO,X-Ray Diffraction (XRD),Combustion synthesis,Multiferroics
更新于2025-09-23 15:23:52
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Magnetization and magnetic resonance in sol-gel derived polycrystalline BiFeO3 film
摘要： The structure and magnetic properties of polycrystalline BiFeO3 films grown on glass substrate using Sol-Gel technique have been investigated. X-ray diffraction (XRD) analysis revealed the average grain size of about 21 nm. The root mean square (RMS) surface roughness of about 50 nm has been obtained for the film by using scanning electron microscope (SEM) technique. Ferromagnetic resonance (FMR) studies showed the presence of macroscopic ferromagnetic magnetization and uniaxial out-of-plane magnetic anisotropy. The temperature dependences of the magnetization of BiFeO3 films registered in zero field cooling (ZFC) and field cooling (FC) regimes revealed a spin glass state. The average magnetic crystallite sizes obtained from the magnetizations studies coincide with the values revealed from the structural studies.
关键词： sol-gel technique,magnetic properties,magnetic materials,multiferroics
更新于2025-09-23 15:23:52
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Sm-mediated dielectric characteristics and tunable magneto-electric coefficient of 0.5Bi1-xSmxFe0.95Mn0.05O3-0.5PbTiO3 composites
摘要： Magneto-electric multiferroic composites have gained a lot of interest these days mainly due to extensive potential of coupling between ferroelectric and magnetic orders. In this work, we present a series of 0.5Bi1-xSmxFe0.95Mn0.05O3 ? 0.5PbTiO3 (x = 0.00, 0.03, 0.06, 0.09, 0.12 and 0.15) composites, prepared by sol-gel auto-combustion and solid state reaction method to explore the tunability of magneto-electric coefficient. X-ray diffraction confirmed the rhombohedraly distorted cubic perovskite and tetragonal structures of BiFeO3 and PbTiO3, respectively. Ferroelectric loops showed that leakage current can be tuned and reduced by Sm-doping. Magnetic analysis showed switching of antiferromagnetic behaviour into weak ferromagnetic behaviour. Saturation and remanent magnetization were also calculated exhibiting an increasing trend with increasing Sm contents. Synthesized composites showed the non-linear frequency dependent dielectric response which was explained on the basis of Maxwell Wagner theory. Time varying conductivity was probed on the basis of polaron mechanism. The optimized composite reveal an enhanced magneto-electric coupling as compared to that of pure BiFeO3 which makes them feasible for the fabrication of multifunctional devices.
关键词： Magneto-electric coupling,Composites,Multiferroics
更新于2025-09-23 15:22:29
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AIP Conference Proceedings [Author(s) PHYSICS, TECHNOLOGIES AND INNOVATION (PTI-2018): Proceedings of the V International Young Researchers’ Conference - Ekaterinburg, Russia (14–18 May 2018)] - Synthesis and investigation of functional layers for composite multiferroics
摘要： This article is devoted to the synthesis and investigation of thin ferroelectric and magnetostrictive layers as potential constituents of composite multiferroics. We chose alloy Fe10Ni90 as magnetostrictive medium. The magnetic anisotropy and magnetoelastic properties of films Fe10Ni90 are investigated. It is shown that they can be significantly modified with a variation in the thickness of the samples in the range 40-80 nm. We chose polyvinylidene fluoride(PVDF) as ferroelectric medium. Its films were obtained by spin-coating and had a thickness of ~200 nm. The analysis of the crystallinity and phase composition of the films are completed. It is established that the factors influencing on these properties are the thickness of the films and the conditions for their heat treatment. The magnetic properties of the PVDF / Fe10Ni90 film structures with optimized parameters of layered components are determinate.
关键词： magnetostrictive,PVDF,ferroelectric,composite multiferroics,Fe10Ni90
更新于2025-09-23 15:21:21
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Synthesis of hollow spheres of BiFeO3 from nitrate solutions with tartaric acid: Morphology and magnetic properties
摘要： Single-phase powders of bismuth ferrite have been synthesized for the first time by ultrasonic spray pyrolysis from nitrate solution in the presence of tartaric acid. The produced powders consist of hollow spherical agglomerates with a mean diameter of ~1 μm. The influence of tartaric acid concentration on the synthesis temperature and morphology of hollow spheres was established. The agglomerate shells have open and closed pores. The mean values of the shell thickness and the ratios of closed and open pores were estimated and their dependence on the concentration of tartaric acid was found. It was shown that the magnetic properties are determined not only by the size of nanoparticles composing the agglomerates, but also by the morphology of hollow sphere shells.
关键词： hollow spheres,morphology,magnetic properties,multiferroics,bismuth ferrite
更新于2025-09-23 15:21:21
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Tuning optical and magnetic properties of nanocrystalline BaTiO3 films by Fe doping
摘要： Fe-doped BaTiO3 is a promising multiferroics material due to its appealing physical properties and potential applications in sensors, transducers and non-volatile memories and multilayer capacitors. Herein, Fe-doped BaTiO3 nanocrystalline films were deposited on silicon substrates by chemical solution route. The relation between Fe content and the optical and magnetic properties of the samples was analyzed. X-ray diffraction data show that the films are tetragonal with P4mm space group. The atomic force microscopy measurement indicates that the film surface roughness increases with Fe composition. The optical response behavior of the films was investigated by Adachi’s dielectric function model with fitting ellipsometric spectra in the photon energy 1.5–4.13?eV. With increasing Fe content, the real part of dielectric functions gradually decreases in the transparent region. Moreover, EOBG (the optical band gap) is reduced with increasing Fe composition x, and the relationship between them is EOBG = (3.817–1.440 × x) eV. All Fe-doped films show weak ferromagnetism coming from the bound magnetic polarons and exchange interaction between oxygen vacancies and Fe3+ in the films. When iron content x exceeds 0.06, the magnetization values of the samples exhibit an unsaturated characteristic at more than 3000 Oe magnetic fields, which is due to the competition between the ferromagnetism and the antiferromagnetism of two Fe3+ ions superexchange. These results suggest that optical and magnetic properties of Fe-doped BaTiO3 nanocrystalline films can be changed by Fe composition.
关键词： multiferroics,optical properties,Fe-doped BaTiO3,magnetic properties,chemical solution route
更新于2025-09-23 15:21:21
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Hexaferrite multiferroics: from bulk to thick films
摘要： We report studies of the structural and microstructural properties of Sr3Co2Fe24O41 in bulk form and as thick films. The precursor powders for the bulk form were prepared following the sol-gel auto-combustion method. The prepared pellets were synthesized at 1200 oC to produce Sr3Co2Fe24O41. The XRD spectra of the bulks showed the characteristic peaks corresponding to the Z-type hexaferrite structure as a main phase and second phases of CoFe2O4 and Sr3Fe2O7-x. The microstructure analysis of the cross-section of the bulk pellets revealed a hexagonal sheet structure. Large areas were observed of packages of hexagonal sheets where the separate hexagonal particles were ordered along the c axis. Sr3Co2Fe24O41 thick films were deposited from a suspension containing the Sr3Co2Fe24O41 powder. The microstructural analysis of the thick films showed that the particles had the perfect hexagonal shape typical for hexaferrites.
关键词： hexaferrite,microstructure,sol-gel auto-combustion,thick films,multiferroics
更新于2025-09-23 15:21:01
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Emergence of two-magnon modes below spin-reorientation transition and phonon-magnon coupling in bulk BiFeO3: An infrared spectroscopic study
摘要： We have studied the low-temperature magnetic and infrared measurements on the BiFeO3 ceramic sample to investigate the behavior of phonons and magnon-phonon coupling below 300 K. From the magnetic study, we noticed two magnetic transitions near 150 and 257 K due to the spin-reorientation. Besides, this sample is found to be a mean-field system rather than a glassy system. In our assignment of the infrared modes, all the 13 allowed phonon modes are accounted for rhombohedral BiFeO3 at room temperature itself. Almost all the modes show anomalous behavior in their frequency dependence, close to the observed magnetic transitions. In addition, the emergence of two-magnon modes at 106 and 111 cm-1 below 160 K is observed due to a modification in the noncollinear spin structure. These results indicate the presence of magnon-phonon coupling in multiferroic BiFeO3 below room temperature.
关键词： infrared spectroscopy,Multiferroics,magnetic properties,magnon-phonon coupling
更新于2025-09-23 15:19:57
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Tailoring the photovoltaic effect in (1a??1a??1) oriented BiFeO <sub/>3</sub> /LaFeO <sub/>3</sub> superlattices
摘要： Ferroelectric and photovoltaic properties of (BiFeO3)(1?x)Λ/(LaFeO3)xΛ superlattices grown by pulsed laser deposition have been investigated (Λ being the bilayer thickness). For a high concentration of BiFeO3 a ferroelectric state is observed simultaneously with a switchable photovoltaic response. In contrast for certain concentration of LaFeO3 a non-switchable photovoltaic effect is evidenced. Such modulation of the PV response in the superlattices is attributed to the ferroelectric to paraelectric phase transition which is controlled with the increase of x. Remarkably, concomitant to this change of PV mechanism, a change of the conduction mechanism also seems to take place from a bulk-limited to an interface-limited transport as x increases.
关键词： photovoltaic effect,ferroelectrics,complex oxides,superlattices,multiferroics
更新于2025-09-23 15:19:57
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Structure Quality of LuFeO3 Epitaxial Layers Grown by Pulsed-Laser Deposition on Sapphire/Pt
摘要： Structural quality of LuFeO3 epitaxial layers grown by pulsed-laser deposition on sapphire substrates with and without platinum Pt interlayers has been investigated by in situ high-resolution X-ray diffraction (reciprocal-space mapping). The parameters of the structure such as size and misorientation of mosaic blocks have been determined as functions of the thickness of LuFeO3 during growth and for different thicknesses of platinum interlayers up to 40 nm. By means of fitting of the time-resolved X-ray reflectivity curves and by in situ X-ray diffraction measurement, we demonstrate that the LuFeO3 growth rate as well as the out-of-plane lattice parameter are almost independent from Pt interlayer thickness, while the in-plane LuFeO3 lattice parameter decreases. We reveal that, despite the different morphologies of the Pt interlayers with different thickness, LuFeO3 was growing as a continuous mosaic layer and the misorientation of the mosaic blocks decreases with increasing Pt thickness. The X-ray diffraction results combined with ex situ scanning electron microscopy and high-resolution transmission electron microscopy demonstrate that the Pt interlayer significantly improves the structure of LuFeO3 by reducing the misfit of the LuFeO3 lattice with respect to the material underneath.
关键词： in situ X-ray diffraction,multiferroics,electron microscopy,pulsed-laser deposition
更新于2025-09-19 17:13:59