Structural, Magnetic and Electrical Properties of Cu Substituted Mn–Zn Soft Nanoferrites

Soft nanoferrites of nominal composition Mn_0.5Cu _x Zn_0.5?x Fe₂O₄ with 0.0??x??0.35 were prepared by chemical co-precipitation method. The formation of single phase spinel structure with different compositions, sizes and macrostructure were confirmed by X-ray diffraction patterns and scanning electron microscopic (SEM) measurements. The lattice parameter decreased with increase in Cu²⁺ content. The crystallite size of the powder samples varied from?14 to 27?nm. The theoretical density increased with increase in Cu²⁺ content. Room temperature saturation magnetization was measured as a function of copper content. The saturation magnetization (Ms) and Bohr magneton (?? _B) increases up to x=0.25 due to increased A?CB interactions in the AB₂O₄ type spinel nanoferrites. Dielectric permittivity, dielectric loss tangent and complex impedance plots were studied in the frequency range 20?Hz?C5?MHz. Loss peak occurs for all the studied compositions and shifts towards low frequency with increased Cu²⁺ content. Complex impedance spectroscopic studies confirmed that conduction in the samples is due to grain boundaries. The high values of DC electrical resistivity support this result.     

Effect of Concentration of Zr4+ and Ni2+ Dopants on Electrical, Magnetic and Y–K Angle of Mg–Cu Complex Spinel Nanoferrites

The complex Mg?CCu nanoferrites with composition Mg_0.5Cu_0.5Fe_2?2x Ni _x Zr _x O₄ (0.00??x??0.80) were synthesized by incorporating dopants Zr⁴⁺ and Ni²⁺ with the help of chemical co-precipitation method. The synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), dc electrical and magnetic properties through laboratory-made two-probe resistivity apparatus and vibrating sample magnetometer (VSM). XRD confirmed the formation of single phase spinel nanoferrites having crystalline size in range 16?C29?nm. The particle size (t) and lattice parameter (a) increase with the increase in concentration of dopants. The XRD results are in good agreement with SEM results. FTIR give valuable information about the presence of tetrahedral (A) and octahedral (B) sites by considering higher and lower frequency bands, respectively. The electrical properties, e.g. dc electrical resistivity (?? _d ), drift mobility (?? _d ) and activation energy?(E), were calculated. Resistivity data confirm semiconducting behavior of material. And it is observed that an abrupt increase in resistivity occurs up to x=0.40. While further increase in dopants concentration leads to decrease in resistivity. Magnetic hysteresis loops confirmed soft nature of synthesized material. Interesting magnetic behavior is observed that up to x=0.40 the value of saturation magnetization (M _s ), remanence (M _r ) and Bohr magneton (n _B ) increase and after that decrease in trend occurs. For x=0.40, minimum coercive force (H _c ) is observed. Y?CK angle increases with increase in dopant concentration. So it is confirmed that the incorporation of dopant in small amount (x??0.40) enhances magnetic properties and further increase of Zr⁴⁺ can weaken magnetic properties.     

Synthesis, Structural, Electrical, Magnetic Curie Temperature and Y–K Angle Studies of Mn–Cu–Ni Mixed Spinel Nanoferrites

Nanoferrites of composition Mn_0.50Cu_0.5−x Ni _x Fe₂O₄ (0.00≤x≤0.50) are prepared by chemical coprecipitation method. The prepared nano-ferrites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), two probe resistivity apparatus, and vibrating sample magnetometer (VSM) to study the compositional, structural, morphological, electrical, and magnetic properties with varying concentration (x) in the composition of the prepared nanoferrites. XRD confirmed formation of single phase spinel ferrite with crystalline size in the range of 16–29 nm. The lattice parameter (a) decreases with a decrease of Cu concentration. Further information about the structure and morphology of the nanoferrites was obtained from SEM and results are in good agreement with XRD. FTIR gives information about distribution of cations and anions by confirming the presence of high and low frequency bands due to tetrahedral and octahedral sites, respectively. The electric properties were measured and analyzed by using homemade two probe resistivity apparatus showing semiconducting behavior of synthesized ferrites. The magnetic hysteresis curves clearly indicate the soft nature of the prepared samples. Various magnetic parameters such as saturation magnetization (M _s), and remanence (M _r) are calculated from the hysteresis loops and observed compositional dependent. Saturation magnetization and magnetic moment increase with Ni content. This is due to the existence of localized canted spin. Coercivity and M _s decreases while Y–K angles increase with Cu²⁺ content. The Ni²⁺ addition improves the magnetic properties. Curie temperature decreases with increase in Cu contents.     

Structural and Magnetic Properties of Nanocrystalline Mg–Co Ferrites

Mg?CCo nano crystalline ferrites having the general formula Mg_1?x Co _x Fe₂O₄ (x=0, 0.05, 0.1, 0.15, 0.2, 0.25) were prepared by the sol?Cgel method. X-ray powder diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR) were carried out to investigate the structural properties of the samples. X-ray powder diffraction patterns indicated the formation of a spinel structure of the prepared compounds. Fourier Transform Infrared (FTIR) spectroscopy of the samples confirmed the XRD results. The crystallite size, lattice parameters and porosity of samples were calculated by XRD data analysis as a function of cobalt concentration. The dielectric constant (?? _r ), dielectric loss tangent (tan???) and ac electrical conductivity (?? _ac) of nanocrystalline Mg?CCo ferrites were investigated as a function of frequency and Co concentration. The frequency dependence of ?? _r , tan??? and ?? _ac is in accordance with the Maxwell?CWagner model. The effect of Co doping on dielectric and electric properties was explained on the basis of cations distribution in the crystal structure. The saturation magnetization M_S, remanent magnetization M_r and coercivity H_C of all samples were explained as a function of cobalt concentration on the basis of Néel??s two-lattice model.     

Structural,Electrical and Dielectric Properties of Co–Mn Spinel Nanoferrites Prepared by Co-precipitation Technique

Cobalt manganese nanoceramics with nominal composition Co_1−x Mn _x Fe₂O₄ (x=0.00, 0.15, 0.30, 0.45, 0.60, 0.75) were synthesized by a chemical coprecipitation technique. The X-ray diffraction patterns revealed the cubic spinel structure. The average crystallite size from the Sherrer formula was in the range of 28 nm–56 nm. The lattice parameter increased with a concentration of manganese. Scanning electron microscopy (SEM) was used for microstructural study. The electrical properties such as electrical resistivity (ρ), drift mobility (μ _d), and activation energy (ΔE) were measured using a two-probe apparatus in the temperature range 323–573 K. The electrical resistivity decreased with temperature and manganese concentration. The dielectric constant (ε′), loss factor or imaginary loss (ε″) and dielectric tangent loss (tan δ) were measured at room temperature using a LCR meter in the frequency range 100 Hz to 5 MHz. All the dielectric parameters decreased with increasing frequency. The AC electrical conductivity (σ _ac) was calculated from the dielectric measurements. It increases with increase of frequency and manganese concentration. The increase in electrical conductivity may be attributed to the formation of Co⁺³ and Mn⁺³ from Co⁺² and Mn⁺³, respectively, at both A and B sites.     

Structural and Magnetic Properties of Zn and Co Substituted Nickel Ferrites Prepared by the Citrate Sol–Gel Method

Three different ferrites with nominal compositions, NiFe₂O₄, Ni_0.50Zn_0.50Fe₂O₄, and Ni_0.50Zn_0.25Co_0.25 Fe₂O₄, were synthesized by wet chemical citrate sol–gel process, mainly to understand how doping with different cations affects the magnetic properties. X-ray diffraction (XRD) confirmed the existence of a single phase without detectable impurities. XRD analysis using the Rietveld refinement technique showed that the samples crystallize in a cubic spinel structure with the Fd-3m space group and the lattice constants were evaluated. Scanning electron microscopy of the calcined samples revealed particles that were approximately 100 nm size. The elemental analysis by energy dispersive spectroscopy showed that the element concentrations were at the stoichiometric ratio in all samples. The magnetic properties measured at room temperature using a vibrating sample magnetometer revealed enhancement in the magnetic properties of nickel ferrite when doped with zinc and cobalt. The high field regimes of the hysteresis loops were modeled using the Law of Approach to Saturation to determine the cubic anisotropy coefficient (K). The anisotropy coefficient increased with doping Zn and Co, which could be explained in terms of the site occupancy of the dopants in the cubic spinel lattice.     

Synthesis, Structural, Electrical and Magnetic Characterization of Mn0.5Mg0.5?x Ni x Fe2O4 Spinel Nanoferrites

Nanoferrites of composition Mn_0.50Mg_0.5?x Ni _x Fe₂O₄ with 0.00??x??0.50 were prepared by the chemical coprecipitation method. The prepared nanoferrites were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), atomic force microscopy(AFM), dc electric resistivity and magnetic properties using vibrating sample magnetometer (VSM) to study the structural, morphological, electrical, and magnetic changes taking place with varying Ni and Mg concentration in the composition of the prepared nanoferrites. The XRD results indicated the formation of single spinel ferrite with crystalline size in the range of 16?C24?nm. The lattice parameter (a) decreased with the decrease of the Mg concentration. IR reveals the presence of both high and low frequency bands due to tetrahedral and octahedral sites, respectively. Further information about the morphology of the nanoferrites was obtained from AFM and SEM measurements. Electrical properties indicate that synthesized samples have high resistivity. The magnetic hysteresis curves clearly indicate the soft nature of the prepared nanoferrites. Various magnetic parameters such as saturation magnetization (M _s ), and remanence (M _r ) are obtained from the hysteresis loops and observed to be dependent on the composition.     

Sol–Gel Auto-combustion Preparation of M2+ = Mg2+, Mn2+, Cd2+ Substituted M0.25Ni0.15Cu0.25Co0.35Fe2O4 Ferrites and Their Characterizations

Journal of Superconductivity and Novel Magnetism - Cost-effective and controllable synthesis of M0.25Ni0.15Cu0.25Co0.35Fe2O4 (M2+ ?=?Mg2+, Mn2+, and Cd2+) ferrites via the sol–gel...     

Annealing Influence on the Microstructure and Magnetic Properties of Ni–Mn–In Alloys Ribbons

We report on the structure, microstructure and inverse magnetocaloric effect associated with the first-order martensitic phase transition, in Heusler Ni_50.0Mn_35.5In_14.5 alloy ribbons. We have studied the short-time vacuum annealing influence at 1048?K, 1073?K, 1098?K, and 1123?K in these properties. At room temperature, an increase in the degree of structural order for ribbons annealed up to 1098 K was observed, corresponding to cubic L2₁ austenite phase. Meanwhile, for the sample annealed at 1123?K a monoclinic 10M martensitic phase was detected. A comparison of magnetic entropy change as a function of the applied field, after using zero-field-cooling thermomagnetic and isothermal magnetization measurements, has been made for the sample annealed at 1073?K.     

Electrical and magnetic properties of Al3+ substituted Mn–Ni–Zn nanoferrites

Nanostructured Mn–Ni–Zn ferrites with composition Mn_0.1Ni_0.6Zn_0.3Al_xFe_(2?x)O₄ (where x = 0.05, 0.1, 0.15, 0.2) have been prepared by sol–gel method. The structural data obtained by X-ray diffraction (XRD) of all Mn–Ni–Zn nanoferrites confirmed the spinel structure. The XRD data was used to calculate the lattice parameter and grain size. The morphology of nanoferrites was studied using scanning electron microscopy. The elemental composition (atomic percentage) was determined with the help of energy dispersive X-ray analyser. The dielectric permeability, AC and DC resistivity for all compositions were measured and discussed. The highest resistivity was measured for the sample with concentration x = 0.1. Vibrating sample magnetometry was used to study the magnetic properties of nanoferrites. High saturation magnetization of value 38.7 emu/g, coercivity 7 Oe and highest initial permeability 83.7 are measured for the sample consisting x = 0.05 Al concentration. These nanoferrites have various applications in core materials and in electronic device technology.     

Structural, Dielectric, and Magnetic Characterization of Nanocrystalline Ni–Co Ferrites

Spinel ferrites containing Nickel and Cobalt of composition with nominal formula Ni_(1?x)Co_(x)Fe₂O₄ (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) prepared by the coprecipitation method are reported. The single phase spinel formation of ferrites was confirmed by X-ray diffraction techniques. The lattice constants (a _th) were calculated based on the ionic radii of the constituents. The calculated lattice constants are smaller than the measured, because for calculations ideal ionic radii are used. The particle size calculated from the Scherrer formula varied within 15 to 33?nm. The dielectric constant and dielectric loss tangent measurement were carried out at room temperature as a function of frequency from 100 Hz to 3 MHz. Both the dielectric constant and dielectric loss tangent increased with increase in cobalt concentration. Ferrimagnetic transition temperature as a function of Co?concentration was measured with the low field ac susceptibility apparatus. The ferrimagnetic transition (T _c ) was observed in the temperature range 573 to 720?K. The T _c decreased with the addition of Co?concentration. The effect of Co?concentration on the magnetic properties was investigated using a vibrating sample magnetometer (VSM). It was found that both magnetic saturation (M _s ) and coercivity (H _c ) increase with Co?concentration.     

Synthesis, Structural, and Magnetic Characterization of Mn1?x Ni x Fe2O4 Spinel Nanoferrites

Nanoferrites of composition Mn_1−x Ni _x Fe₂O₄ with x=0.00, 0.25, 0.50, 0.75, 1.00 were prepared by the chemical coprecipitation method. The prepared nanoferrites were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) and vibrating sample magnetometer (VSM) to study the compositional, structural, morphological and magnetic changes taking place with varying Ni concentration in the composition of the prepared nanoferrites. IR reveals the presence of both high-frequency and low-frequency bands due to tetrahedral and octahedral sites, respectively. The XRD results indicated the formation of single spinel ferrite with crystalline size in the range of 14–26 nm. The lattice parameters (a) decrease with the increase of the Ni concentration x in the lattice. Further information about the morphology of the nanoferrites was obtained from the AFM and SEM results. The magnetic hysteresis curves clearly indicate the soft nature of the prepared nanoferrites. Various magnetic properties such as saturation magnetization (M _s ) and remanence (M _r ) are calculated from the hysteresis loops and observed to be dependent on the composition.     

Structure and Nonlinear Electrical Properties of Ni–Fe–Mg–O Epilayers

NiFe₂O₄-based epilayers grown on MgO substrates and exhibitingS-type negative-resistance behavior were characterized by x-ray diffraction, Mössbauer spectroscopy, and electron probe x-ray microanalysis. The current–voltage characteristics of the epilayers were measured at different temperatures in air, water, and liquid nitrogen, and the activation energy for conduction was evaluated. The near-surface and interfacial regions of the films were shown to differ in the nature of disordering as a result of the through-thickness variation in composition.     

Electrical and Magnetic Properties of the Pr2/3 + xTiO3 ± yPerovskite Phase

The thermoelectric power, electrical resistivity, and magnetic susceptibility of the praseodymium titanium bronze phase Pr_{2/3 + x} TiO_{3 ± y} were measured for compositions in the range 0 x 1/3. The conductivity of the bronze was found to exhibit metallic behavior between 77 and 450 K. The transport data were used to evaluate the electron mobility and Fermi energy. In the range 77–300 K, the magnetic susceptibility of Pr_{2/3 + x} TiO_{3 ± y} consists two contributions—those from Pr³⁺(a strong function of temperature) and Ti³⁺(a weak function of temperature).     

The Effect of Annealing Temperature on the Magnetic Properties of Mn x Co1?x Fe2O4 Ferrites Nanoparticles

Mn _x Co_1?x Fe₂O₄ ferrites compounds (0??x??0.6) have been synthesized by a glycol-thermal method from high-purity metals chlorides. Single phase spinel structure of the nanoparticles has been confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. The diameters of the as-prepared powders were estimated from XRD and TEM and were found to be in the range: 7 to 13?nm. Room temperature magnetizations were obtained using a vibrating sample magnetometer (VSM) on the as-prepared samples and on samples annealed at 500 and 700?°C. The variation of coercive fields, saturation and remnant magnetizations as a function of composition (x) and grain size have been investigated. ⁵⁷Co M?ssbauer spectra for as-prepared samples were also measured at different temperatures (27, 100, and 200?°C). Significant changes in magnetization properties and M?ssbauer parameters are observed across the composition range studied. The variation of coercive fields and saturation magnetizations appear to critically depend on the particle sizes as the compounds evolve from single domain to multidomain structure.     

Characterization and Magnetic Properties of Nanoparticle Ni1?x Zn x Fe2O4 Ferrites Prepared Using Microwave Assisted Combustion Method

Nanoparticle Ni_1?x Zn _x Fe₂O₄ (x=0.35,0.45) samples were prepared successfully via microwave assisted combustion method. Synthesis of nanosize materials at a low temperature using a domestic microwave oven is the unique feature of this method and is being tried for the first time to produce NiZn ferrites. Single-phase formation of the samples was confirmed from X-ray analysis and IR spectrum. XRD data reveals that lattice parameter increases with Zn content ??x??. Particle sizes calculated from XRD analysis are in good agreement with TEM results. Extent of spin canting at octahedral B-site is deduced from Yafet?CKittel angles. Surface properties and reduced particle size affects the Curie temperature.     

Electrical and Magnetoresistance Properties of Mg x Mn1−x Fe2O4 Compounds

A systematic study of the electrical properties and magnetoresistivity of Mg _x Mn_1?x Fe₂O₄ (x ranging from 0 to 1.0 in steps of 0.1) compounds is presented. All samples were produced by glycolthermal reaction under a low reaction temperature of 200 ^°C. The X-ray diffraction data indicate formation of a pure cubic spinel phase in all the samples. The effects of Mg concentration and particle size on the properties have been investigated. A decreasing trend in the resistivity of all the compounds with increasing magnetic field has been observed.