Doped Mn Zn Research Articles

Impact of high energy photons on physical, structural and magnetic properties of Mn0.65Zn0.35Fe2-xNdxO4 nanoparticles

Ultrafine powders of Nd+3 doped Mn–Zn ferrite powders with composition Mn0.65Zn0.35Fe2-xNdxO4 (x = 0.04, 0.06, 0.08) were prepared using the combustion method of preparation. Monophasic nanoparticle formation was confirmed by X-ray diffraction. The particle size was determined using a Transmission electron microscope (TEM). The nanopowders were investigated for their physical, structural, and magnetic properties and then radiated with gamma photons obtained from Co60 source with a dose of 500Gy, 750Gy and 1000Gy. The characterization of radiated powders showed preservation of spinel structure with breaking down of crystallites into finer crystals with increment in amorphous content. Structural and physical parameters were drastically altered due to high-energy photon exposure. The breaking down of larger particles was observed as a result of photon energy impact on the samples. The Saturation magnetization of ferrite nanoparticles was observed to increase with increasing gamma radiation dose. Mössbaure spectra showed the dominance of Fe+3 in the high spin state.

Structural and magnetic properties of gadolinium substituted Mn0.6Zn0.4GdxFe2−xO4 (x = 0–0.1) spinel ferrite

Soft magnetic ferrites Mn0.6Zn0.4GdxFe2-xO4 (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) have been synthesized using a solvothermal method. X-ray diffraction analysis revealed the structure of Gd3+ doped Mn-Zn ferrite was spinel structure. In response to an increase in Gd3+ content, the lattice constant of the sample increased and then decreased, and the largest lattice constant was 8.452 Å with x = 0.04. The crystallite size varied between 14.7 and 18 nm. M−H data revealed that all samples are soft magnetic and characterized by the larger saturation magnetization, low remnant magnetization and coercively. We found that the Gd3+ ions substituted into Fe3+ ion sites and resulted an increase in Gd3+ content from x = 0 to x = 0.1, which lead to the saturation magnetization first increased then decreased. The maximum saturation magnetization value of Mn0.6Zn0.4GdxFe2-xO4 was 90.1 emu/g with x = 0.04, which suggested the Mn0.6Zn0.4Gd0.04Fe1.96O4 was magnetically responsive, and could be used in hyperthermia tumor applications.

Effect of Dy3+ substitution on microwave behaviour of nanocrystalline Mn-Zn Ferrite

Microwave-hydrothermal (M-H) method had been employed to synthesize a series of Dy3+doped Mn-Zn ferrite Mn0.6Zn0.4Fe2–xDyxO4 (x=0, 0.01, 0.03, 0.05, 0.07, 0.09) nanopowders at 160°C/30 min. The prepared samples have been characterized by Fourier Transform Infrared Spectrometer. The grain size of sintered ferrites are in the range of 60-70 nm. Decrease in saturation magnetization and increase in coercivity were observed with an increase of Dy3+ concentration in Mn-Zn ferrites. The complex permeability and complex permittivity of the prepared samples were measured in the frequency range of 2–18 GHz using a using a vector network analyzer. It is observed that small variation of Dy3+ substitution in spinel ferrite tailored microwave absorbing parameters dramatically. The reflection loss (RL) increased with the Dy3+ content upto x ≤ 0.03. The sample with x=0.03 of thickness 2.3 mm showed minimum reflection loss of -20.5 dB with a bandwidth of 3.8 GHz. Thus the present materials exhibit good microwave absorption properties and hence can act as EMI suppressors. Copyright © 2018 VBRI Press.

Synthesis of La-doped Mn0·6Zn0.4LaxFe2-xO4 and the study of its structural, electrical and magnetic properties for high frequency applications

Lanthanum doped Mn–Zn Ferrite nanoparticles, Mn0·6Zn0.4LaxFe2-xO4 (x = 0.00–0.10 in steps of 0.02), employing oxides of raw materials has been prepared by the conventional solid state reaction (SSR) route. The structural characteristics of resulting ferrite products are investigated by powder X-ray diffraction (XRD) confirming the formation of spinal cubic crystal structure of Mn–Zn Ferrite with privileged orientation along (311). The crystallite size, lattice constant, dislocation density, strain and other microstructural parameters have been traced as a function of the La content (x). FTIR results demonstrate the existence of functional groups associated with Mn–Zn ferrite observing the corresponding peaks at 423 cm−1 and 529 cm−1. The Eg values are lying between 1.23 eV and 1.30 eV studied by exploiting UV–Vis absorption. The ferromagnetic behavior of Mn–Zn ferrite products has been found with the help of PPMS. The saturation magnetization (MS) of bare sample is much larger than that of doped ferrites and decreases with the increasing amount of La content. The coercivity (HC) increases with La introduction and the remnant magnetization reduces from 0.8447 emu/gm to 0.1436 for lower La content (x = 0.02), while it increases at higher La content (x = 0.04–0.10). Dielectric properties and AC resistivity have been extracted from the measurement of impedance analyzer at ambient temperature. The values of dielectric constant are found to be higher in bare Mn–Zn ferrite than La doped Mn–Zn ferrite products.

Rapid response in recovery time, humidity sensing behavior and magnetic properties of rare earth(Dy & Ho) doped Mn–Zn ceramics

In the present world, the development of room temperature humidity sensor materials has always been a very popular research field. Rare earth (RE) doped ferrites are considered as potential resistive humidity sensing material owing to its high remarkable surface morphology with high porosity. Recent studies have shown that ferrite ceramics have good response in recovery time and have excellent humidity sensing behavior. With this in mind, solution combustion synthesis was used to effectively prepare RE dysprosium (Dy3+) and holmium (Ho3+) doped Mn–Zn ferrite ceramics with the chemical formula Mn0·5Zn0.5DyxHoyFe2-xO4 (x = 0.005 to 0.03) (MZDHF) (where x, y = 0.0, 0.01, 0.015, 0.02, 0.025 and 0.03). The MZDHF XRD pattern revealed the purity of the samples without any secondary phase. The crystallite size MZDHF is in the nano range. Further, the calculated lattice parameter of MZDHF is found to be increasing with the RE content. The two prominent major absorption bands related to A-site and B-site were confirmed by FTIR spectra. The hysteresis loops of MZDHF are used to investigate the differences in magnetic properties with an Dy3+-Ho3+ concentration. The remanence magnetization, saturation magnetization, coercivity and anisotropy of the ferrites were determined. The saturation magnetization decreases with increase of Dy3+-Ho3+ concentration. The change in the surface resistance for all the samples was studied. Among all the samples, Mn0·5Zn0.5Dy0.03Ho0.03Fe1·96O4 composite has shown a drastic variation in resistance. And the corresponding sensing response for the same sample is found to be 99%. Along with this, the sample has shown a least hysteresis and good stability. Also, the Mn0·5Zn0.5Dy0.03Ho0.03Fe1·96O4 composite has shown a good timing behavior of 90 s and 18 s. The sensing mechanism for the prepared Mn0·5Zn0.5Dy0.03Ho0.03Fe1·96O4 composite was thoroughly discussed.

Effects of La3+ doping on the structure, properties and application of Mn–Zn ferrite

In this study, the La doped Mn–Zn nanoferrites were synthesized through hydrothermal method, and then were used to activate persulfate for degrading azo dye the Direct Blue 15 (DB15). The structure and morphology of the as-prepared sample were characterized by X-ray Diffraction (XRD), Fourier Transformed Infrared Spectrometer (FTIR), Transmission Electron Microscopy (TEM) and Energy Dispersive Spectrometer (EDS). The results indicated that the La doped Mn–Zn ferrite was successfully synthesized in this study. Four absorption bands were observed in FTIR spectra and assigned to the corresponding site bonds. Mn0.6Zn0.4LaxFe2-xO4 was chosen as catalysts to activate persulfate (PS/Mn0.6Zn0.4LaxFe2-xO4) to decolorize the DB15. It was found that the DB15 was degraded effectively by PS/Mn0.6Zn0.4LaxFe2-xO4 systems. Furthermore, the influences of synthesized conditions (such as the temperature, holding time and doping content of La) of Mn0.6Zn0.4LaxFe2-xO4 on the DB15 decolorization were analyzed. The results indicated that the doping of La can significantly improve the DB15 degradation, 100% degradation of DB15 can be obtained by PS/Mn0.6Zn0.4La0.09Fe1.91O4 within 15 min. The enhancement of synthesized holding time of Mn0.6Zn0.4LaxFe2-xO4 at 160 °C can also increase the DB15 decolorization, and the degradation rate of the DB15 reached almost 100% within 25 min when using Mn0.6Zn0.4La0.05Fe1.95O4 synthesized at 160 °C for 13 h as catalyst.

Dielectric properties of superparamagnetic titanium doped nanophased Mn–Zn ferrites for high frequency applications

Effect of Ti4+ ions on Structural, Dielectric and Magnetic properties of nanophasedMn0.5Zn0.5TixFe2–4x/3(x = 0.0, 0.01, 0.02,0.03, 0.04 and 0.05) ferrites synthesized by hydrothermal method is studied. XRD peaks reveal pure spinel phase without extra peaks. Lattice parameter (a) is found to vary non-linearly with dopant concentration (x). An overall decrease in Crystallite Size (D) (varying from 78 nm–41 nm) with x is witnessed. Values of dielectric constant () and loss factor (tan δ) of Ti4+ doped Mn–Zn ferrites are lower than that of the undoped sample. Increase of AC resistivity (ρ) by an order of 10 in Ti4+ doped Mn–Zn ferrites is ensued due to locking of Ti4+–Fe2+ pairs. Lowered values of Ms is attributed to spin canting due to growth of nanosized grains, weakening of exchange interactions by non-magnetic Ti4+ doping and lower values of x-ray density. Transition from single to multi- domain region of Mn–Zn–Ti ferrites is clearly evinced from the plot of Coercivity (Hc) with D. Reduced value of coercivity to zero upto a critical size of ∼49 nm indicates the existence of superparamagnetism in these ferrites. Superparamagnetismis first ever reported in the present caseof Ti4+ doped Mn–Zn ferritessynthesized by hydrothermal method. Relatively lowered values of (29–18), tan δ (of the order of 10–2–10–3), higher values of ρ (106 Ω—cm) and lowered values of Hc obtained with Ti4+ doping improve the eddy current losses and direct these materials for high frequency applications.

Influence of Ce3+ substitution on the structural, electrical and magnetic properties of Zn0.5Mn0.43Cd0.07Fe2O4 spinel ferrites

In this paper, the effect of Ce3+ ions addition on the microstructure, electrical and magnetic behaviour of Cadmium doped Mn–Zn ferrites was investigated. A series having composition Zn0·5Mn0·43Cd0·07Fe2-yCeyO4 (y = 0.0–0.7) was synthesized by wet chemical route. X-Ray Diffraction (XRD) analysis showed that prepared particles having size in nano-regime having cubic spinel structure with preferred (311) plane. Weakening of (311) plane intensity and emergence of secondary phase with Ce3+ ion concentration verified the substitution of Ce3+ ions in the spinel lattice of ferrite. The crystallite size varied between 46.4 and 67 nm as the concentration of Ce3+ ions increased from x = 0.0–0.7. Temperature and composition dependent electrical resistivity and activation energy values were calculated by current-voltage (I–V) characteristics in the temperature range 423–823 K by two probe method. It was observed that DC Resistivity and activation energy of synthesized nanoparticle ranges between109 to ~1010 Ohm cm and 11.78–2.56 eV respectively with increasing the concentration of Ce3+ ions. MH curves of prepared samples showed the paramagnetic nature of spinel feerites. The reported data suggested that these particles promising candidates for high-frequency applications.

Structural, morphological, magnetic and optical study of co-precipitated Nd3+ doped Mn-Zn ferrite nanoparticles

Abstract Superparamagnetic nanoparticles have astounding applications in the field of biomedical. Co-precipitated Nd3+ doped Mn0.5Zn0.5NdxFe2−xO4, where x = 0, 0.025, 0.050, 0.075, 0.1 ferrite nanoparticles are examined utilizing various characterization methods at room temperature. XRD, FE-SEM and FTIR analysis reveal the origination of cubical spinel ferrite structure. A transition from paramagnetic to superparamagnetic nature has been observed with Nd3+ addition (x > 0.025). To comprehend the relationship of structural and magnetic properties a cation distribution has been proposed and found to be in agreement with experimental observations. Absorption spectra show a red shift with Nd3+ doping. PL spectra show a blue shift in band edge emission upto x = 0.050. The results obtained from UV–visible spectroscopy and PL spectroscopy show an anti-Stokes shift with Nd3+ doping owing to the photon upconversion process. The obtained magnetic results in fusion with optical results for ferrite nanoparticles are prospective in imaging and biomedical applications.

Reduced A–B super exchange interaction in Sm3+–Gd3+-doped Mn–Zn ferrites due to high energy gamma irradiation

We report the effect of gamma irradiation on structural and magnetic properties of $${\text{Mn}}^{2 + }_{0.4} {\text{Zn}}^{2 + }_{0.6} {\text{Sm}}^{3 + }_{x} {\text{Gd}}^{3 + }_{y} {\text{Fe}}^{3 + }_{2 - (x + y)} {\text{O}}_{4}$$ (where x = y = 0.01, 0.02, 0.03, 0.04 and 0.05) ceramics prepared by self-propagating high-temperature synthesis method using glucose and urea as fuels. The synthesized samples are characterized through X-ray diffractometer (XRD) and vibration sample magnetometer at room temperature before and after gamma irradiation. The XRD patterns of before irradiation samples reveal the formation of polycrystalline, mixed spinel cubic structure. The mixed (impurity) phases are identified as Fe2O3, SmFeO3 and GdFeO3, and the amount of these residual phases is comparatively less after gamma irradiation. Lattice parameter is found to be increasing with increasing Sm3+ and Gd3+ concentration is observed after gamma irradiation. This is due to the irradiation of ionizing gamma radiation with the material which gives rise to the production of lattice defect and then the displacing of atoms from their equilibrium position. The magnetic properties reveal that saturation magnetization (Ms), remnant (Mr), remnant ration (Mr/Ms), coercivity (Hc), magneton number (ηB), anisotropy constant (K) have been decreasing with increasing Sm3+ and Gd3+ concentration before and after gamma irradiation. This is due to breaking of ferrimagnetic ordering, surface state pinning and cation inversion of the materials. Hence, our results propose the good radiation stability of the samples when compared to reported material stability in the literature.

Laser induced adjustment of the conductivity of rare earth doped Mn-Zn nanoferrite

AbstractTwo series of Mn-Zn nanoferrites (namely Mn1-xZnxFe2O4and Mn1-xZnxFe2-yRyO4) were synthesized using standard ceramic technique. X-ray diffraction and FT-IR were employed in the chacterization of the nanopowder. The X-ray density for each sample increased after laser irradiation which was correlated with the decrease in the unit cell volume. The study involved the thermal and frequency variation of the dielectric constant and AC conductivity of the investigated samples before and after laser irradiation. The later altered the conductivity by decreasing its value for the rare earth doped samples except for the Sm3+doped one. The results suggested the exploitation of Mn-Zn doped rare earth nanoferrites in many technological applications demanding high resistivity.

Gd3+ doped Mn-Zn soft ferrite nanoparticles: Superparamagnetism and its correlation with other physical properties

Superparamagnetic nanoparticles are very important in biomedicine due to their various applications like drug delivery, gene delivery in the body and also used for hyperthermia. In the present work, superparamagnetic nanoparticles of Mn0.5Zn0.5GdxFe2-xO4 (x=0, 0.025, 0.050, 0.075, 0.1) ferrites have been prepared by co-precipitation method. Thorough characterizations (XRD, FTIR, FE-SEM, EDS, VSM and fluorescence spectroscopy) have proved the formation of cubical spinel superparamagnetic nanoparticles of soft ferrites. A cation distribution has been proposed for the determination of various important theoretical parameters for these samples. With the addition of Gd3+ nanoparticles have shown the superparamagnetism at room temperature confirmed by VSM analysis. Photoluminescence (PL) spectra shows a blue shift (for x=0.025, 0.075) which may be due to quantum confinement.

Synthesis, investigation on structural and electrical properties of cobalt doped Mn–Zn ferrite nanocrystalline powders

Abstract Synthesis of CoxMnyZnyFe2O4 (x = 0.1, 0.5, 0.9 and y = 0.45, 0.25, 0.05) nanocrystalline powders was done by chemical co-precipitation method. The crystal structure was determined by using X-ray diffraction (XRD) studies. The crystallite size and lattice parameters were calculated from the XRD data. The XRD results revealed that the crystallite size of the nanocrystalline powder was found to decrease from 37 nm to 28 nm with the substitution of cobalt. The effect of cobalt ions on the crystallization process, the lattice parameters and electrical properties of Mn–Zn ferrites has been also investigated. The AC conductivity increased with an increase in frequency but it decreased with an increase in cobalt content. The complex impedance analysis of the data showed that the resistive and capacitive properties of the Co–Mn–Zn ferrite are predominant due to the fact that the processes are associated with the grains and grain boundaries. The dielectric constant and dielectric loss dependence on doping level and frequency at room temperature were also studied.

Structural, morphological, magnetic and dielectric characterization of nano-phased antimony doped manganese zinc ferrites

Nano-phased doped Mn–Zn ferrites, viz., Mn0.5−x/2Zn0.5−x/2SbXFe2O4 for x=0 to 0.3 (in steps of 0.05) prepared by hydrothermal method are characterized by X-ray diffraction, Infrared and scanning electron microscopy. XRD and SEM infer the growth of nano-crystalline cubic and hematite (α-Fe2O3) phase structures. IR reveals the ferrite phase abundance and metal ion replacement with dopant. Decreasing trend of lattice constant with dopant reflects the preferential replacement of Fe3+ions by Sb5+ion. Doping is found to cause for the decrease (i.e., 46–14nm) of grain size. An overall trend of decreasing saturation magnetization is observed with doping. Low magnetization is attributed to the diamagnetic nature of dopant, abundance of hematite (α-Fe2O3) phase, non-stoichiometry and low temperature (800°C) sintering conditions. Increasing Yafet–Kittel angle reflects surface spin canting to pronounce lower Ms. Lower coercivity is observed for x≤0.1, while a large Hc results for higher concentrations. High ac resistivity (~106ohm-cm) and low dielectric loss factor (tanδ~10−2–10−3) are witnessed. Resistivity is explained on the base of a transformation in the Metal Cation-to-Oxide anion bond configuration and blockade of conductivity path. Retarded hopping (between adjacent B-sites) of carriers across the grain boundaries is addressed. Relatively higher resistivity and low dielectric loss in Sbdoped Mn–Zn ferrite systems pronounce their utility in high frequency applications.

Finite size effect on Sm3+ doped Mn0.5Zn0.5SmxFe2−xO4 (0≤x≤0.5) ferrite nanoparticles

Samarium doped Mn–Zn ferrite nanoparticles of composition Mn0.5Zn0.5SmxFe2−xO4 (0≤x≤0.5) have been synthesized by a chemical co-precipitation method for developing low Curie temperature stable ferrofluid. These samples were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Electron Paramagnetic Resonance (EPR) spectroscopy and search coil method analytical techniques for their structural, morphological and magnetic properties. X-ray diffraction patterns confirmed the formation of crystalline single spinel phase of as grown nanoparticles. Lattice parameter and lattice strain increases with the increase in Sm3+ content. SEM images revealed the presence of ultrafine particles and their agglomerated structures in higher Sm3+ ions concentration analogues. The stoichiometry of the final product agreed well with the initial substitution composition as evidenced by EDS data. Electron paramagnetic resonance (EPR) spectra proved the ferromagnetic nature of nanoparticles. The magnetic measurements by search coil method showed superparamagnetism for x=0, 0.1 the samples with saturation magnetization of 23.95emu/g for Mn0.5Zn0.5Fe2O4 sample which increases with rise in Sm3+ ions content. The results are explained and correlated with the structural, morphological and magnetic properties for developing stable kerosene based ferrofluid by using these nanoparticles.

Improved structural, electrical and magnetic properties of Mn–Zn–Cd nanoferrites

Cd doped Mn–Zn nanoferrites of the composition Mn0.4Zn0.6CdxFe2−xO4, with (0.0≤x≤0.5) have been synthesized by a co-precipitation method. The X-ray diffraction patterns of the samples confirmed the formation of a single-phase cubic spinel structure. Average crystallite size is found to be in the range of 35–40nm, which is in consistence with transmission electron microscopy results. The average grain size as calculated from scanning electron microscopy is found to be 100nm. DC resistivity is found to be about 10 times higher than the reported values. Specific saturation magnetization is observed to be increasing from 25.23emu/g to 48.93emu/g with cadmium concentration. Magnetic moment is increasing from 1.07BM to 2.35BM with increasing concentration of Cd2+ ions. Variation of anisotropy constant as a function of concentration of doping is also discussed. Comparatively higher DC resistivity, refined crystallite size and improved magnetization are the main achievements of the present investigation.

Effect of synthesis on structural and magnetic properties of cobalt doped Mn–Zn nano ferrites

A series of Co2+ doped Mn–Zn ferrite ceramics with the formula Mn0.5Zn0.5−xCoxFe2O4 (x=0, 0.25 and 0.50) have been successfully synthesized using polyethylene glycol-assisted co-precipitation and hydrothermal methods. The structural characterization of the samples has been done using room temperature X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD patterns revealed the formation of pure FCC spinel phase without any impurity peaks. SEM showed the uniform, homogenously spherical nanoparticles prepared from controlled reaction of hydrothermal method. Lattice constant found to be smaller for samples prepared from hydrothermal treatment. The average crystallite size of all nanoparticles were estimated using Scherrer’s formula and found to lie between 10–25±3nm with small size distribution of particles prepared by hydrothermal method. Bond length (A–O) and ionic radii (rA) at A-sites are smaller than the bond length (B–O) and ionic radii (rB) at B-sites for sample series prepared by two methods. Magnetic properties were studied using Physical Property Measurement System (PPMS), Quantum Design Vibrating Sample Magnetometer (VSM) option. Magnetic properties including saturation magnetization was higher (65emu/g for x=0.25) for hydrothermal treated samples. The method of preparation influenced the size of particle which in turn has strong affect on magnetic properties of prepared samples. The enhanced magnetic and structural properties of these nano ferrites made them a potential candidate to use in electromagnetic devices.

Effect of Gd3+ ion distribution on structural and magnetic properties in nano-sized Mn–Zn ferrite particles

Nanoparticles of Gd3+ ions doped Mn0.5Zn0.5GdxFe2−xO4 (x=0.1, 0.2, 0.3, 0.4) mixed ferrite were prepared using chemical co-precipitation method. The X-ray diffraction measurements confirmed the formation of a cubic spinel structure. The structural parameters like crystallite size, lattice parameter and strain induced have been calculated. The lattice parameter increases with the increase in Gd3+ ion concentration and shows non linear behaviour. HRTEM investigation confirms the nano size formation of the Gd doped Mn–Zn ferrite nanoparticles. EPR was used to evaluate resonance peak intensity, Lande’s splitting factor (g value), peak to peak line width (ΔHp–p), spin concentration (Ns) and relaxation time (τs). Line width, line intensity, relaxation time and spin concentration increase with Gd3+ ions doping (for x=0.1 to x=0.3) and then decrease for x=0.4, whereas the g value shows the reverse trend for the same composition. IR spectra shows two strong absorption bands at 570cm−1 and 416cm−1 of tetrahedral and octahedral bond stretching respectively in all the samples. IR spectrum also shows that Gd3+ occupies the octahedral B-sites. Magnetic parameters such as saturation magnetization (Ms), remanence (Mr) and coercivity (Hc) were measured by search coil method. The value of saturation magnetization increases from 29.94emu/gm for x=0.1 to 46.01emu/gm for x=0.4.

Frequency dependent dielectric measurements of Cd2+ doped Mn-Zn nano ferrites prepared by sol gel and coprecipitation methods

Ferrite powders of Mn-Zn doped with Cd2+ (Mn0.5CdxZn0.5-xFe2O4) were prepared by the sol gel auto- combustion and coprecipitation methods. The effect of Cd2+ doping on the crystalline phase formation was investigated by X-ray diffraction which confirms the spinel structure of prepared samples. Crystallite size found to be lower for samples prepared by coprecipitation method. The samples prepared using coprecipitation, found to be denser as compared to sol gel method. SEM analysis confirmed the nano structure of the prepared samples. Dielectric properties were studied using impedance analyzer (20 Hz – 5 MHz) and RF material analyzer (1 MHz – 3 GHz) respectively. DC electrical measurements showed highly resistive nature of the prepared samples and values are high for samples prepared from sol gel method. Impedance spectroscopic analysis was carried out in the frequency range from 20 Hz to 5 MHz for the prepared samples, showing resistance of grain boundary is higher than grains. Impedance plane plots gave information about the resistive and reactive parts of impedance. The presence of semicircular arcs at lower frequency side, confirms that the high resistance of samples is due to increase in the number of grain boundaries in the nano synthesised samples.

Enhancement of electrical and magnetic properties of Cd2+ doped Mn–Zn soft nanoferrites prepared by the sol–gel autocombustion method

Nanocrystalline Mn–Zn soft ferrites with chemical formula Mn0.5Zn0.5−xCdxFe2O4 (x=0.0–0.35) were synthesized using the sol–gel autocombustion method. The formation of single phase cubic spinel structure was confirmed from X-ray diffraction (XRD) pattern for all samples. The average crystallite size was calculated using Scherrer's formula and it remains within the range 24–50±2nm. The structural parameters, lattice constant, XRD density, polaron length, polaron radius, lattice strain and porosity, have been calculated using XRD data. The variation in dielectric constant, dielectric loss tangent, AC conductivity and complex impedance analysis were studied in the frequency range from 20Hz to 5MHz at room temperature. The values of dielectric constant and loss tangent were found to be lowest for the concentration x=0.25. The high values of DC electrical resistivity (2.2×1011Ωcm at 373K) and activation energies suggests the conduction in Cd2+ doped Mn–Zn ferrite system is due to hopping of polarons. Complex impedance plane plots were used to separate the grain and grain boundary effects in Mn0.5Zn0.5−xCdxFe2O4. Vibrating sample magnetometer measurements carried out at room temperature shows that saturation magnetization and magnetic moment increased with increase in cadmium content up to x=0.25. The addition of Cd improves the magnetic and electrical properties of Mn–Zn ferrites.