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We report sol–gel auto-combustion synthesis of Ni1-xCdxFe2O4 (0.0–0.72) nano-ferrites (grain-diameter:13.8–28.6 nm) with no thermal-treatment and, its study by x-ray diffraction (XRD), scanning-electron-microscopy-energy-dispersive-x-ray-spectroscopy (SEM-EDS), vibration sample magnetometery, ultraviolet–visible (Uv–Vis) spectroscopic techniques. XRD, EDS confirm formation of spinel phase, with minor-presence of α-Fe2O3 phase. Results show linear increase of lattice parameter; strong compositional dependence of: cationic-distribution (Fe3+ Ni2+ ions more-populated on B-site, Cd2+ distributed on A, B site); inversion-degree; oxygen-parameter; very-similar mean-particle-agglomerate-size; variation of B-O-B A-O-B A-O-A super-exchange-interaction affect magnetic properties. Magnetism is governed by Yafet-Kittel three-sub-lattice model; studied samples remain in the overlap region between single/ multi-domain structures.

Co1−xFe2+xO4 (x = 0.0–0.8) spinel nano ferrite dry gel powders were synthesized by sol gel auto-combustion method. Synthesized samples were investigated by using X-ray diffraction (XRD), magnetic measurements, Ultraviolet–visible (Uv–Vis); Fourier transform infrared (FTIR) spectroscopy. XRD validates the formation of spinel phase, and incorporation of Co, Fe in spinel lattice. Results reveal that compositional variation leads to: i) cationic re-distribution; ii) allowing fine-tuning of bandgap with strong correlation among Bandgap – Fe3+ ions on B-site; iii) changes in degree of inversion; iv) variation of disorder; v) shows better soft magnetic behavior; vi) surface spin disorder leads to reduction of saturation magnetization; vii) observed changes in Debye temperature suggest modification of lattice vibrations.

We report synthesis, characterization of Zn1-xNixFe2O4 (x = 0.0–1.0) nano ferrites, by using x-ray diffraction 'XRD', vibration sample magnetometery, UV–Vis spectroscopy. XRD validates the formation of fcc spinel structure. Ni-addition leads to: grain diameter modification; linear decrease of lattice parameter; un-equal distribution of both Ni2+, Zn2+, Fe3+ ions on A, B sites; changes in the degree of inversion, and oxygen parameter showing changes in disorder; linear variation of bandgap; significant reduction of coercivity with simultaneous increase of saturation magnetization. Results clearly demonstrate that Ni-addition in Ni-Zn ferrite can be effectively used to tune magnetic properties, bandgap.

Structural, magnetic properties, bandgap of sol gel auto-combustion synthesized single phase CoCrxFe2-xO4 (x = 0.0–1.0) nano ferrites, were studied by x-ray diffraction, vibration sample magnetometer, ultra violet visible spectroscopy. Linear decrease of lattice parameter with increasing Cr-content is ascribed to difference between ionic radii of Cr3+ (0.064 nm), Fe3+ (0.067 nm). Linear decrease of grain diameter with increasing Cr-content, shows presence of Cr in spinel lattice which hinders grain growth. Results show bandgap tenability; reveal that Cr-addition is effective in determining coercivity, saturation magnetization of studied samples. Results illustrate effectiveness of compositional variation for structural modification, leads to tuning of magnetic properties, bandgap.

Ni0.8Zn0.2Fe2O4 nano-powders were prepared by solution combustion method by using metal nitrates, citric acid, green fuel (plant extracts). The structural, magnetic characteristics of as prepared, annealed Ni0.8Zn0.2Fe2O4 samples were determined by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), vibrating sample magnetometer (VSM). XRD confirms the formation of single phase nano-crystalline (grain size: 12.7−32.7 nm) cubic spinel structure of annealed samples. Studied mixed ferrite shows relocation of Ni2+, Zn2+, Fe3+ ions between A, B site. Coercivity of annealed samples ranges between 29.7 to 124.9 Oe. Obtained saturation magnetization of annealed samples (34.56−54.96 Am2/kg) is a combined effect of weakening of A-B, A-A, and strengthening of B-B interaction, and surface dead layer (0.80−1.25 nm) on particles, arising due to spin disorder at surface.

We report synthesis of Li0.5-0.5xMgxFe2.5-0.5xO4 (x=0.0, 0.1, 0.4, 0.6, 0.8, 1.0) ferrite, utilizing honey green synthesis via sol gel auto combustion method (without any post-preparation thermal treatment). X-ray diffraction (XRD), vibrating sample magnetometer (VSM) were used to monitor structural, magnetic properties. XRD validates the formation of nanocrystalline spinel phase with Scherrer’s grain diameter varies between 21.5 – 27.9 nm. Results reveal that Mg2+ addition: i) changes experimental lattice parameter (aexp), showing incorporation of Mg2+ ion in the spinel lattice, ii) changes the cation distribution showing presence of that both Li1+, Mg2+ ions on A, B site, iii) modifies inversion parameter (δ) shows transition from inverse to mixed spinel structure, leads to reduction of saturation magnetization (Ms (exp)), iv) alters Ms, understood in terms of cationic redistribution at A, B-sites, v) alters coercivity (Hc), range between 101.4 – 889.9 Oe, vi) shows similar trend of both experimental ‘Ms (exp)’, theoretical ‘Ms (t)’saturation magnetization, reveal that magnetization behavior of the studied samples is governed by Neel model.

Influence of stress transverse-induced anisotropy on the magneto-impedance effect (MI) in Fe 75 Si 15 Nb 3 B 6 Cu 1 ribbons has been studied. The linear part and the maximum value of MI ratio are directly linked to both permeability and frequency. Shape anisotropy also influences the transfer curve. The corresponding values of MI ratio and sensitivity to applied field for the highest linear field range (up to 53.8 Oe) are 8.3% and 0.15%/Oe, respectively. The maximum values of Δ Z / Z sat and sensitivity obtained in the field range of 42.5–55 Oe, are 120% and 9.65%/Oe.

An extensive analysis of high-precision electrical resistivity ( ρ ) data taken on Fe- and Co- based metallic glass wires over the temperature range 10 K⩽ T ⩽300 K and discussion of the results, so obtained, in terms of the existing theoretical models identifies enhanced electron–electron interaction (EEI), weak localization (WL) and electron–magnon (EM) scattering as the main mechanisms governing the temperature dependence of ρ in these systems and determines their relative magnitudes accurately. Out of the inelastic processes that destroy phase coherence, inelastic electron–phonon scattering turns out to be the most effective one and its dephasing action persists to temperatures as high as 300 K. While EEI and WL effects are basically responsible for the negative temperature coefficient of resistivity (TCR), EM scattering accounts for the positive TCR. The observed resistivity minima are thus an outcome of these competing contributions to ρ ( T ).

High-frequency (45 MHz-6 GHz) magnetoimpedance response in amorphous Co/sub 83.2/Mn/sub 7.6/Si/sub 5.9/B/sub 3.3/ glass-coated microwires has been studied using conventional furnace annealing and Joule heating. Conventional annealing deteriorates, while Joule heating enhances the magnetoimpedance response.

Summary form only given. The giant magnetoimpedance effect (GMI) in soft magnetic ribbons and wires consists in a large impedance change under an applied magnetic field. The discovery of this effect, having an electromagnetic origin, has gained a renewed interest in soft amorphous alloys due to promising application as magnetic sensors. An alternative method to evaluate the magnetotransport properties of soft magnetic materials at high frequencies is highlighted here and measurements performed on glass-coated Co-based microwires will be presented. The magnetoimpedance effect in amorphous Co/sub 83.2/Mn/sub 7.6/Si/sub 5.9/B/sub 3.3/ microwires (metallic diameter/spl sime/20 /spl mu/m, glass-coating thickness/spl ap/5 /spl mu/m), prepared by the Taylor-Ulitovsky method, was studied in a wide frequency interval (30 MHz/spl divide/6 GHz) by means of a network analyser.

It is shown in the present paper that gradually devitrified Co-based non-magnetostrictive metallic glass is an excellent model material to verify Louis Neel's theory of the Rayleigh rule. In the course of the calculations, Neel showed that the parameter p = bH c /a (where H, is the coercivity, a and b are the coefficients of a quadratic polynomial expressing the Rayleigh rule) is expected to range between 0.6 (hard magnets) and 1.6 (soft). However, the experimental values of this parameter, reported in the literature for a number of monoand poly-crystalline magnets, are much greater than those expected from the theory presented by Neel (in some cases even by two orders of magnitude). The measurements, performed for a series of Co-based metallic glass samples annealed at gradually increasing temperature to produce nanocrystalline structures with differentiated density and size of the crystallites, have shown that the calculated values of the parameter p fall within the range expected from Neel theory.