Gagan Kumar; Virender Pratap Singh; Arun Kumar; Jyoti Shah; Shalendra Kumar; B.S. Chauhan; R.K. Kotnala; M. Singh
Abstract
We investigated the effects of In 3+ and Co 2+ substitutions on the structural and magnetic properties of Mg-Mn ferrites. The cation distribution technique was taken into account to estimate the magnetic interactions. Cation distribution was also used to investigate the ionic radii of tetrahedral and ...
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We investigated the effects of In 3+ and Co 2+ substitutions on the structural and magnetic properties of Mg-Mn ferrites. The cation distribution technique was taken into account to estimate the magnetic interactions. Cation distribution was also used to investigate the ionic radii of tetrahedral and octahedral sites, oxygen positional parameter, site bond as well as edge lengths, bond lengths and bond angles. The ionic radius of tetrahedral site and octahedral site was observed to increase with the incorporation of In 3+ and Co 2+ ions respectively. Theoretical lattice parameter was observed to increase with the substitution of In 3+ and Co 2+ ions. In 3+ substitution resulted in weakening of super-exchange interactions while in Co 2+ substituted Mg-Mn ferrites, anisotropy was observed to play a decisive role in addition to bond lengths and bond angles.
Virender P. Singh; Gagan Kumar; Pooja Dhiman; R. K. Kotnala; Jyoti Shah; Khalid M. Batoo; M. Singh
Abstract
In the present work BaFe12O19 nano-hexaferrite had been synthesized by sol-gel method and then characterized for its structural, electric, dielectric and magnetic properties. X-ray diffraction studies confirmed the hexagonal structure of the prepared nanohexaferrite with no secondary phase and the particle ...
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In the present work BaFe12O19 nano-hexaferrite had been synthesized by sol-gel method and then characterized for its structural, electric, dielectric and magnetic properties. X-ray diffraction studies confirmed the hexagonal structure of the prepared nanohexaferrite with no secondary phase and the particle size was found to be of the order of 49 nm. Further, the morphology of the sample has been studied by using transmission electron microscopy (TEM). A high value of the DC resistivity (5.5 × 106 Ω cm), has been obtained at room temperature. The dielectric properties such as dielectric constant (ε′), dielectric loss tangent (tan δ) and ac electrical conductivity (σac) are investigated as a function of frequency. The dielectric constant and loss tangent are found to be decreasing with the increase in frequency while ac electrical conductivity is observed to be increasing with the increase in frequency. The dielectric properties have been explained on the basis of Maxwell-Wagner’s two-layer model and hopping of the charge. The magnetic properties such as initial permeability (µi) and relative loss factor (RLF) have been investigated as a function of frequency in the range 75 kHz to 30 MHz .Fairly constant value of initial permeability and low values of RLF of the order of 10-4 over a wide frequency range are the cardinal achievements of the present work. The room temperature M-H study shows that present nanohexaferrite has high value of coercivity (2151.3 Oe) and high saturation magnetization (32.5 emu/gm), which make present nanohexaferrite very suitable for magnetic applications. The M-T study shows that prepared nano-hexaferrite has high Tc (746 K).
Jaspreet Kaur; Jasneet Kaur; Jyoti Shah; R.K. Kotnala; Vinay Gupta; Kuldeep Chand Verma
Abstract
In the present work, structural, microstructural and magnetoelectric (ME) coupling of multiferroic Ba(Fe0.01Ti0.99)O3 (BFT1) nanowires have been studied. BFT1 nanowires were prepared by a hydrothermal method with reaction temperature 180 o C for 48 hours. The X-ray diffraction shows that BFT1 is polycrystalline ...
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In the present work, structural, microstructural and magnetoelectric (ME) coupling of multiferroic Ba(Fe0.01Ti0.99)O3 (BFT1) nanowires have been studied. BFT1 nanowires were prepared by a hydrothermal method with reaction temperature 180 o C for 48 hours. The X-ray diffraction shows that BFT1 is polycrystalline with cubic phase. The calculated value of distortion ratio (c/a) is ~ 1. No impurity or extra phase is observed. The micrographs by transmission electron microscopy reveal nanowires like structure of BFT1with diameter lie in the range of ~ 40 - 50 nm and length greater than 1.5 μm. The ME coefficient measurement shows that the ME coupling under the effect of both ac and dc bias. It shows strong dependence on ac and dc bias applied field. The value of linear coefficient (α) called ME coefficient is calculated as ~ 16 mV/Oecm at a fixed frequency of 850 Hz. This ME coefficient α corresponds to induction of polarization by a magnetic field or of magnetization by an electric field. The observed optimum dc bias field at which the maximum magneto-electric coupling occurs is ~ 750 Oe. The magnetization hysteresis shows strong ferromagnetism.
