Structural, electrical and magnetic properties of (Cu/Co)Fe2O4 spinel ferrite materials

Journal of Electronic Materials, 2018

Structural, electrical and magnetic properties of nickel manganite ceramics obtained by sintering fine powders prepared by a complex polymerization method are given in this work. The phase composition of the synthesized material was examined by x-ray powder diffraction (XRPD). Field-emission scanning electron microscopy (FE-SEM) was used to analyze the obtained powder morphology. Scanning electron microscopy (SEM) was used to analyze the microstructure of sintered ceramics. The activation energy of conduction E a and the coefficient of temperature sensitivity B 25/100 were calculated from direct current (DC) resistivity measurements. The magnetization dependence of temperature M(T) and alternating current (AC) susceptibility data obtained from SQUID measurements clearly demonstrate that quadruple magnetic phase transitions can be readily detected at T M1

Materials Research, 2012

This study evaluates the structural, microstructural, electric and magnetic properties of nickel ferrite samples prepared through the solid state reaction. It was observed that an increase in the sintering temperature produces a higher cation concentration in the A site when compared to the B site. The assessment of magnetic properties showed that an increase in grain size leads to a decrease in the coercive fields verging on superparamagnetic values, while the saturation magnetization increases up to 46.5 Am 2 .kg-1 for samples sintered at 1200 °C. The dc electric resistivity behavior of samples was attributed to the increase in the cross-sectional area of grains as well as the different oxidation states and distribution of cations amongst the lattice sites of the spinel structure.

Journal of Materials Science: Materials in Electronics, 2021

compounds have been prepared by standard solid-state reaction technique and sintered at 1000, 1100, 1150, 1200, and 1250°C for 5 h in air. The effect of sintering temperature on the structural, morphological, magnetic, dielectric, and electrical properties of these spinel ferrites has been studied thoroughly and comparatively. Formation of the single-phase cubic spinel structure of these compositions is confirmed by X-ray diffraction analysis. The lattice constant increases with sintering temperature as well as with 5% scandium (Sc 3?) doping in Ni-Cu-Zn ferrite. Surface morphology reveals that the grain size increases with sintering temperature. Among the prepared ferrites, Ni 0.3 Cu 0.2 Zn 0.5 Sc 0.05-Fe 1.95 O 4 has the maximum density (5.05 9 10 3 kg/m 3) at sintering temperature 1150°C, which gives the highest value of initial permeability. It is observed that initial permeability varies with sintering temperature, and it gives the maximum value at optimum sintering temperature. It is noted that Curie temperature decreases with 5% Sc 3? ions doping, whereas it slightly increases with increasing sintering temperature for both compositions. Ni 0.3 Cu 0.2 Zn 0.5 Fe 2 O 4 compound shows the highest Curie temperature 418°C. Dielectric constant, dielectric loss factor and AC electrical conductivity decrease with 5% Sc 3? ions doping in Ni-Cu-Zn ferrite. The initial permeability decreases sharply at Curie temperature, which indicates a high degree of compositional homogeneity. The 'Hopkinson' peak is observed just below the Curie temperature in the real part of initial permeability versus temperature graphs. The mechanism of dielectric polarization and electrical conductivity has been explained based on the electron hopping between Fe 3? and Fe 2? ions. The variation trend of complex

Journal of Materials Science: Materials in Electronics

In this study, Ni 0.25 Cu 0.13 Zn 0.62 Fe 2 O 4 polycrystalline ferrites were synthesized through a solid-state reaction route. The standard techniques such as XRD, FTIR, FESEM, EDX, and VSM were employed to analyze and understand the crystallized single-phase, crystallite size, functional groups, morphology and magnetic properties. FTIR and XRD analyses revealed the different band modes in structure, formation and the compositions of the cubic spinel structure. FESEM revealed that the grain size increases as the sintering temperature increases and the presence of the required elements as per the stoichiometric ratio were ascertained by EDX. The longitudinal wave velocity (V l), transverse wave velocity (V t), mean elastic wave velocity (V m), bulk modulus (B), rigidity modulus (n), Young's modulus (Y), Poisson ratio () and Debye temperature (Θ D) were evaluated. The elastic moduli were corrected to zero porosity through Hasselman and Fulrath model and Ledbetter and Datta model. The dielectric constant increases with sintering temperature which is accounted for the partial reduction of Fe 3+ to Fe 2+ and exhibited dispersive behavior as a result of Maxwell-Wagner-type interfacial polarization. The small polaron hopping phenomenon is responsible for the electrical conduction process. The initial permeability was found to increase with sintering temperature as a result of the increased densities and grain sizes. The Q-factor decreases and the cutoff frequency shifts toward the lower frequency side with sintering temperature. The magnetic parameters drastically deteriorate with sintering temperature which may be ascribed to the sample inhomogeneity and presence of intragranular porosity. Keywords Ni 0.25 Cu 0.13 Zn 0.62 Fe 2 O 4 • Sintering • Microstructure • Elastic property • Electromagnetic properties

Journal of Superconductivity and Novel Magnetism, 2018

Ni 0.6 Cd 0.2 Cu 0.2 Fe 2 O 4 ferrites were synthesized using sol-gel method under different sintering temperatures. XRD patterns with the Rietveld refinement indicate that samples crystallize in the cubic spinel structure. The increase of sintering temperature leads successively to the increase of lattice constant, average crystallite size, intensities of absorption bands, magnetization, and electrical conductivity of the prepared ferrites. Dielectric constants decrease with frequency and their behaviors have been investigated using the interfacial polarization theory predicted by Maxwell. The modulus analysis shows the presence of electrical relaxation phenomenon and non-Debye nature for the samples. An appropriate electrical equivalent circuit was used to analyze the Nyquist plots, and the results show that the conduction mechanism of the synthesized ferrites is mainly due to the grain boundary contribution.

IEEE Transactions on Magnetics, 2000

The Fe 3 O 4 powder was mixed with Cu-ferrite powder then sintered in an argon atmosphere at temperatures between 1000 C and 1250 C for 4 h. The Cu-ferrite content in the mixture powder was between 0 mol% and 30 mol%. The effects of Cu-ferrite content and sintering temperature on the magnetoresistance (MR) and microstructure of the sintered ferrite were investigated. It was found that the Cu ions were dispersed uniformly in all sintered samples by the analysis of Cu element mapping of the scanning electron microscopy. The maximum MR ratio of the sintered ferrite at room temperature is about 7.3% when Cu-ferrite content was 7.28 mol% and sintering temperature was 1200 C. From the plot of log versus T 1 2 curves and the measurement of the current versus voltage curves of the sintered samples, it can be known that the magnetoresistance mechanisms in these sintered samples are the contribution of spin-polarized tunneling effect.

Materials Today: Proceedings, 2020

This paper communicates a comparative study on structural and magnetic properties obtained by two different routes. It is seen that X-ray density increases by 2%; Coercivity and Residual magnetization is almost doubled for MS sintered compositions in comparison to corresponding CS sintered compositions. However, for each composition, grain size and saturation magnetization remained almost same. Interestingly, Magnetostriction varies linearly with magnetic field only for MS Sintered samples. Results are explained in the light of microstructural studies.

Journal of Alloys and Compounds, 2009

Magnetic particles of nanocrystalline cobalt ferrite has been synthesized successfully by polymeric precursor method and the influence of the calcination temperature on the particle sizes and magnetic properties of the synthesized samples have been also investigated. The particles have been calcined at different temperatures varying from 400 to 800 • C. The studies carried out using XRD, FT-IR, SEM, TEM, STA (TG-DTG-DTA) and VSM techniques. The results indicated that the ferrite samples obtained by this method had the nanocrystalline pure single-phase spinel structure and good magnetic properties. TEM images showed almost spherical nanoparticles which are uniform in both morphology and particle size distribution with sizes varied in the range of 13-145 nm with the calcination temperature. The gradual increase in the crystallite size with the calcination temperature indicates the formation of bigger particles on the calcination. Magnetic properties of the products were found greatly affected by the average crystalline size of the nanoparticles. The saturation magnetization and remanent magnetization values of the samples increased as a function of the calcination temperature. Our results showed this method facilitates the magnetic tunability of the Co-ferrite nanoparticles by using the proper temperature of the thermal treatment and greatly expanding the range of applications.

Ni 0.8 Co 0.2 À 2x Cu x Mn x Fe 2 O 4 ferrites (with x ¼ 0.01, 0.03, 0.05, 0.07 and 0.09) were prepared using solution combustion route. X-ray diffraction analysis indicates the presence of the characteristic most intense (311) peak along with other reflections confirming the formation of spinel ferrite in each composition. SEM images show formation of porous structured agglomerates with submicron sized grains. The microstrain measurement of ferrite series is non-linear with variation in dopant concentration for a given magnetic field. The magnetic hysteresis at room temperature indicates the ferrimagnetic behavior of synthesized ferrite system. The magnetic and mechanical properties were seen to be comparatively higher for x ¼0.07 composition. The presence of sexset in Mössbauer spectra confirms the ferrimagnetic nature of all the ferrites.

RSC Advances, 2019

This work focuses on the microstructural analysis, magnetic properties, magnetocaloric effect, and critical exponents of Ni0.6Cd0.2Cu0.2Fe2O4 ferrites.

Journal of Materials Science: …, 2002

Powders of spinel type ferrite, Cox MnmCrnNik Fe3À xmnk O4, have been prepared by a coprecipitation method. The spinel type ferrite was obtained by pre-sintering at 200±1000 C for 30±120 min in air. In order to optimize the conditions to prepare ferrites of the highest crystallinity, ...

Journal of Advanced Dielectrics

Spinel ferrite Ni[Formula: see text]Mn[Formula: see text]Zn[Formula: see text]Fe2O4 was prepared by a conventional ceramic process followed by sintering at three different temperatures (1050[Formula: see text]C, 1100[Formula: see text]C and 1150[Formula: see text]C). X-ray diffraction (XRD) investigations stated the single-phase cubic spinel structure and the FTIR spectra revealed two prominent bands within the wavenumber region from 600 cm[Formula: see text] to 400 cm[Formula: see text]. Surface morphology showed highly crystalline grain development with sizes ranging from 0.27 [Formula: see text]m to 0.88 [Formula: see text]m. The magnetic hysteresis curve at ambient temperature revealed a significant effect of sintering temperature on both coercivity ([Formula: see text] and saturation magnetization ([Formula: see text]. Temperature caused a decrease in DC electrical resistivity, while the electron transport increased, suggesting the semiconducting nature of all samples and that ...

Journal of Alloys and Compounds, 2009

Soft Ni-Mg spinel ferrites having general chemical formula Ni 1−x Mg x Fe 2 O 4 (0 ≤ x ≤ 1) with increment 0.25 were prepared by the co-precipitation method. The samples were characterized by X-ray diffraction (XRD) technique at room temperature. The analysis of XRD data showed the crystallite size variation within the range 10-13 nm. The electrical and magnetic properties of the synthesized ferrites have been investigated as a function of temperature. The DC electrical resistivity ( ) decreases with increase in temperature exhibiting the semiconductor like behavior. The drift mobility ( d ) and activation energy ( E) are also reported. The dielectrical properties such as dielectric constant (ε ) and dielectric loss tangent (tan ı) are investigated as a function of frequency. The Curie temperature (T c ) of the present work was determined from AC magnetic susceptibility ( ) data and observed variation are explained on cations distribution among tetrahedral (A) and octahedral (B) sites.

Journal of Materials Science: Materials in Electronics, 2017

In this present work, we studied the effect of Nickel substitution on the structural, electrical and magnetic property of Ni x Mg 1−x Fe 2 O 4 (x = 0.00, 0.10, 0.20 and 0.30) synthesized by sol-gel auto combustion technique and characterized by various method such as the X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), vibrating sample magnetometer (VSM) and dielectric properties. The XRD pattern reveals the single phase cubic spinel structure and the lattice parameters values of range 8.368-8.394 Å were observed. Surface morphology and particle sizes were studied by using FE-SEM. The dielectric constants have been ascribed to Maxwell-Wagner and Interfacial theory in agreement with Koop's phenomenological theory. The resistance values decrease with increasing temperature which showed negative temperature coefficient. The decreasing tendency of saturation magnetization was owing to the enhancement in the substitution of Nickel cations in Magnesium ferrites. The coercivity value increases under the control of Nickel content in Mg ferrites. The behavior of Mg-Ni ferrite is ferromagnetic at room temperature which is applied in various technological and industrial areas like magnetic sensor, high frequency device and recording tape.

2008

The effects of sintering temperature and dwell time on the magnetostrictive properties of polycrystalline cobalt ferrite synthesized by the conventional ceramic method have been investigated. The present study showed that the magnitude of magnetostriction strongly depends on the microstructure of the final sintered product. The presence of small and uniform grains with less porous structure in the sintered material leads to enhancement of the magnetostrictive strain. Higher magnetostriction is obtained for samples sintered at a relatively lower temperature of 1100°C. These results are further corroborated by analyzing the effect of some additives during sintering on the microstructural and magnetostrictive properties.