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The aluminium doped barium hexaferrite BaFe12-xAlxO19 with x =0.0, 1.0, 2.0, 4.0 and 6.0 have been synthesized by the sol-gel method to modify the magnetic properties for technological applications. The crystal structure and phase purity of all the samples have been explored by employing the X-ray diffraction (XRD) technique. It confirms that the sample is nanocrystalline, hexagonal symmetry and all the intense peaks could be indexed to the P63/mmc space group. The obtained lattice parameters from the XRD analysis decrease with the increase in Al3+ content in the samples. The microstructural morphology and particle sizes of all samples were studied by using the Field Emission Scanning Electron Microscopy (FESEM-Hitachi-S4800) technique. The magnetic hysteresis (M-H) loops measurement has been carried out at room temperature by employing the vibrating sample magnetometer (VSM) over a field range of +20 kOe to -20 kOe. The magnetic hysteresis (M-H) loops revealed the ferromagnetic (hard magnetic materials) nature of the samples and, analyzed by using the Law of Approach to Saturation. [ABSTRACT FROM AUTHOR]

The article presents the temperature dependent dielectric behavior of chromium substituted cobalt ferrite (CoFe2-xCrxO4, x = 0.0, 0.1, 0.2, 0.3, 0.4). It is observed that the temperature variation of dielectric constant is similar to that of conventional ferroelectricalmaterials. Two transition temperatures called TD and TM has been observed in the dielectric versus temperature plots. The behavior of the spin flipping frequency with respect to temperature has been analyzedby employing the power law. The present study can help to understand the temperature and frequency variation of dielectric behavior in not only cobalt ferrite, but also it can be extended to other ferrites. [ABSTRACT FROM AUTHOR]

0.5BiFe0.80Ti0.20O3-0.5Co0.5Ni0.5Fe2O4(BFTO-CNFO) multiferroic composite was prepared by planetary ball mill method. X-ray diffraction analysis confirms the formation of the compound with the simultaneous presence of spinel Co0.5Ni0.5Fe2O4 (CNFO) and perovskite BiFe0.80Ti0.20O3 (BFTO) phase. Temperature dependent dielectric permittivity and loss tangent were studied with a frequency range of 100Hz to 1MHz. AC conductivity study was performed to analyze the electrical conduction behaviour in the composite. Johnscher’s power law was employed to the AC conductivity data to understand the hopping of localized charge carrier in the compound. The binding energy, minimum hopping distance and density of states of the charge carriers in the composite were evaluated from the AC conductivity data. Minimum hopping distance is found to be in order of Angstrom (Å). [ABSTRACT FROM AUTHOR]

Bi1-xLaxFe1-xMnxO3 ceramics with x = 0.00, 0.05, 0.10 and 0.20 were synthesized by the tartaric acid modified sol-gel technique with required optimization. The co-substitution suppresses the impurities phases in bismuth ferrite which is usually observed. It was observed that the composition-driven structural transition from rhombohedral (R3c space group) to orthorhombic symmetry (Pbnm space group) plays an important role in modifying the dielectric properties of bismuth ferrite. The dielectric constant was found to be increased in La and Mn co-substituted BiFeO3 due to significant large off-center movement of Fe3+ ions in the oxygen octahedra. The dispersion of dielectric constant in the frequency range of 100 Hz to 1 MHz has been analyzed by employing the modified Debye's function which suggests the contribution of multiple charge carriers in the dielectric relaxation. [ABSTRACT FROM AUTHOR]

(1-x)Cobalt ferrite-(x)reduced graphene oxidenanocomposites with x=0, 0.1, 0.2 and 0.3 were prepared by the ultrasonic method. The crystal symmetry modification due to reduced graphene oxide and cobalt ferrite interaction has been studied by employing the X-ray diffraction technique. Morphology of the samples was studied by the Field emission scanning electron microscopy (FE-SEM). Study on electrical properties of the cobalt ferrite-reduced graphene oxide nanocomposites explores the possible application of these composites as anode material. Impedance decreases with an increase in frequency as well as temperature, which supports an increase in ac electrical conductivity. The modified Debye relaxation model can explain the behavior of impedance in cobalt ferrite-reduced graphene oxide nanocomposites. [ABSTRACT FROM AUTHOR]

Bi1-xLaxFe1-xMnxO3 ceramics with x = 0.00, 0.05, 0.10 and 0.20 were synthesized by the tartaric acid modified sol-gel technique with required optimization. The co-substitution suppresses the impurities phases in bismuth ferrite which is usually observed. It was observed that the composition-driven structural transition from rhombohedral (R3c space group) to orthorhombic symmetry (Pbnm space group) plays an important role in modifying the dielectric properties of bismuth ferrite. The dielectric constant was found to be increased in La and Mn co-substituted BiFeO3 due to significant large off-center movement of Fe3+ ions in the oxygen octahedra. The dispersion of dielectric constant in the frequency range of 100 Hz to 1 MHz has been analyzed by employing the modified Debye's function which suggests the contribution of multiple charge carriers in the dielectric relaxation. [ABSTRACT FROM AUTHOR]

The PVDF-CoFe1.5Cr0.5O4 (PVDF-CFCO5) nanocomposite films are synthesized with different weight % of CoFe1.5Cr0.5O4 as filler in PVDF matrix. X-ray diffraction pattern detected the existence of α and β phases and, also validate the result by Fourier transform infrared microscopy. The inclusion of CFCO5 nanoparticles in the polymer medium initiates the alteration of phase between α and β and, offers the nanocomposites greater mobile charge carriers which contribute in the interfacial polarization. The dielectric properties of PVDF-CFCO5 films have superior dielectric constant and considerably a lesser dissipation factor (tan δ) as compared to pure PVDF as well as pure cobalt ferrite. The dielectric constant decreases at higher concentrations of CFCO5 due to agglomeration of the nanoparticles. Thus, their controlled inclusion in a polymer medium to get improved electrical properties will have a significant impact to the present day research. The enhanced dielectric constant of PVDF-CFCO5 film can be utilized for wide applications such as dielectric material for capacitor application. [ABSTRACT FROM AUTHOR]

Cobalt ferrite of different average crystallites (from nanocrystallite to micro crystallites) has been prepared by the Sol-Gel Method. The X-ray diffraction (XRD) analysis confirms the cubic spinel phase with no trace of impurity phases. The effect of annealing temperature on micro structure and electric transport properties as a function of frequency and temperature has been studied. It is observed that the electric impedance and conductivity are strongly dependent on grain size. The impedance spectroscopic study is employed to understand the electrical transport properties of cobalt ferrite. [ABSTRACT FROM AUTHOR]

The Cr3+ substituted BaFe12O19 has been synthesized by modified sol-gel method to tailor the magnetic anisotropy and coercivity for technological applications. Some basic studies have revealed that this substitution leads to unusual interactions among the magnetic sublattices of the M-type hexaferrite. In order to investigate these interactions, BaFe12-xCrxO19 (x = 0.0, 0.5, 1.0, 2.0, and 4.0) M-type hexaferrites were characterized by employing XRD (X-ray Diffractometer). It is confirmed that, all the samples are in nanocrystalline and single phase, no impurity has been detected within the XRD limit. The magnetic hysteresis (m-H) loops revealed the ferromagnetic nature of nanoparticles (NPs). The coercive field were increasing with the increasing Cr3+ content, but after the percolation limit it decreases. The magnetocrystalline anisotropy is increasing with the Cr3+ concentration in samples and high values of magnetocrystalline anisotropy revealed that all samples are hard magnetic materials. Magnetic hysteresis loops were analyzed using the Law of Approach to Saturation method. [ABSTRACT FROM AUTHOR]

Effect of lattice distortion on diffuse phase transition in BNBTO solid solutions near Morphotropic phase boundary (MPB) has been investigated. Solid solutions of (Bi0.5Na0.5)1−xBaxTiO3 (with mole % of x= 0.04, 0.05, 0.06, 0.07 and 0.08) were prepared by the planetary ball mill method in ethanol medium. Rietveld refinement technique with rhombohedral (R3c) and tetragonal (P4bm) crystal symmetry has been employed for structural as well as phase analysis of the solid solutions. Both rhombohedral and tetragonal lattice distortion (c/a) tends toward the pseudo-cubic crystal symmetry with the increase of mole fraction of Ba2+ near MPB (x= 6 mole %). Also, the average crystallite size and grain size decrease with increase of mole fraction of Ba2+ in BNT ceramic are due to larger ionic radius of Ba2+ and grain boundary pinning process in the solid solutions respectively. Additionally, depolarization temperature (Td) and maximum temperature (Tm) reduces due to the lattice distortion of both the phases in BNBTO solid solutions, which is explained extensively. Significant increase of dielectric constant has been observed near MPB composition (x=6%) in BNBTO solid solutions. [ABSTRACT FROM AUTHOR]