Nickel Cobalt Ferrite Research Articles

Effect of Ho3+ Ion Doping on Thermal, Structural, and Morphological Properties of Co–Ni Ferrite Synthesized by Sol-Gel Method

Rare earth Ho3+-substituted Co–Ni ferrites having a chemical formula Co0.6Ni0.4Fe2−xHoxO4 (0.0, 0.025, 0.05, 0.075, and 0.1) were prepared via sol-gel route. The phase formation of these samples was confirmed by the thermogravimetric analysis with differential thermal analysis and X-ray powder diffraction techniques. Rietveld refinement confirms the cubic spinel structure of the prepared samples having space group Fd3− m with presence of secondary phase of α-Fe2O3. The lattice parameter is increased from 8.412 to 8.582 A with Ho3+ ion concentration in cobalt–nickel ferrite from x = 0 to x = 0.1. The distribution of cations has been studied with the help of X-ray diffraction data and it is found that Ho3+ ions preferred to occupy the octahedral [B] site. The other structural parameters like X-ray density, bulk density, hopping length, and allied parameter are increased with the composition of Ho3+ ions in the Co–Ni ferrite. The morphology of the samples was observed by transmission electron microscopy and scanning electron microscopy showed the nanostructured formation.

Fabrication and characterizations of structurally engineered lanthanum substituted nickel-cobalt ferrites for the analysis of electric and dielectric properties

Concerning to the exuberant applications in the field of electrical and dielectric materials, group IV elements lie at the heart of many electronic devices and received significant attention owing to its chemical stability and high oxygen affinity. Among that Ni-Co ferrite especially delivers multi-applications. Present work reports the facile synthesis of Ni-Co ferrite with the substitution of rare earth lanthanum metal for the investigation of electric and dielectric behaviour through a structural, morphological point of view. Several analytical techniques subsequently evaluated the effect of lanthanum on the structural, physical-chemical, morphological, thermal and overall properties of Ni-Co ferrites. The results indicated that the crystalline size of Ni-Co ferrite synthesized by sol–gel auto combustion method gradually decreased with the Lanthanum composition increased in composites. Additionally, the lattice constant, bulk density and porosity of the composite materials investigated. Substitution of lanthanum has a strong influence on electric and dielectric behaviour of the Ni-Co ferrite composites results into increment in the electrical conductivity of Ni-Co-La ferrite composites. On the other hand, the dielectric constant and dielectric loss decreased with the increase in frequency. Overall incorporation of lanthanum ensured the improvement in the electric and dielectric behaviors of Ni-Co ferrites.

Fabrication of Cerium Doped Nickel-Cobalt Ferrite by Co-Precipitation Method

In the modern world researchers caught the attraction towards spinal ferrites. The current work is based on spinel ferrites having formula Ni0.5Co0.5CexFe2-xO4 where (x = 0.0, 0.05, 0.1, 0.15, 0.2) Prepared by co-precipitation method. The confirmation of spinal ferrite structure was done through XRD analysis. The crystallite size was found to be in the range of 8 to 11 nm. Lattice perimeter is observe to obey the increasing trend due to replacement of larger ionic radii of cerium with smaller ionic radii of iron. Koop's phenomenological theory, Maxwell–Wagner interfacial polarization and Vegard’s law is used to explain the behavior of lattice constant. The electrical properties of prepared ferrites were revealed by impedance analyzer. Various parameters like real and imaginary parts of dialectic constant, impedance and modulus was determined. In the frequency range of 1 to 3 GHz the detailed electrical inspection was done. During the electrode polarization the effect of grains on the increasing substitution of cerium was analyzed through real and imaginary parts of electrical modulus M' and M". In the frequency range of 3 GHz the value of M' is 2.1934 × 10-1 to 2.6581 × 10-1 and the value of M" is from 4.67 × 10-3 to 3.538 × 10-3. AC conductivity spectra shows a non-Debye relaxation behavior and it dependents of conductivity on frequency. The observed dielectric constant, dialectic loss and tangent loss are found to be decreasing with the increase in frequency. The investigation shows that real and imaginary impedance Z' and Z" was found to be decreasing on lower frequencies and on higher frequencies all the curves merge with each other. The value of Z' and Z" at 3GHz frequency is in the range of 8.02 × 10-3 to 0.6073 and 3.7641 × 101 to 4.5617 ×101 respectively. Increase in frequency increases the AC conductivity. The applications of prepared nanoparticles are suggested in high frequency devices because of the splendid dielectric properties of these particles.

Magnetic, elastic, dielectric, microwave absorption and optical characterization of cobalt-substituted nickel spinel ferrites

Magnetic, elastic, dielectric, microwave absorption and optical properties of nickel cobalt ferrites Ni1-xCoxFe2O4(x=0.0,0.15,0.30,0.45,0.60,0.75,0.90,1.0) synthesized using Pechini’s sol–gel method are investigated. Saturation magnetization, coercivity and Curie temperature increased with doping of cobalt. An optimized combination of high MS (86.12 emu g−1) and lower coercivity (694.7 Oe) was obtained for composition NC 0.90. Curie temperature increased from 602 °C to 705 °C as amount of Co increased from 0.0 to 1.0. In FT-IR spectrum, characteristic absorption bands were observed in 400–600 cm−1 range. Impedance analyzer was used to determine dielectric and impedance properties in 20 Hz–120 MHz frequency range. The prepared ferrites were evaluated for their applications in 12.4–18 GHz frequency band using vector network analyzer (VNA). Minimum reflection loss of −44.48 dB at 15.74 GHz frequency was obtained for composition NC 0.90. Optical spectra at excitation wavelength of 350 nm show sharp peaks around 330 nm in all the compositions.

Magnetoelectric interactions in bismuth sodium-potassium titanate-nickel cobalt ferrite lead-free composite ceramics

Bismuth sodium-potassium titanate (BNKT) and nickel-cobalt ferrite (NCF) ceramic composite materials (xBNKT-(100-x)NCF), with different ferrite proportions, were studied. Piezoelectric and ferrite powders were separately synthesized by the solid-state method. Structural analyses were carried out by X-ray diffraction and Raman spectra studies of the composites whereas microstructural studies were performed by Scanning Electron Microscopy and the element distribution was studied by Energy Dispersive X-Ray Spectroscopy. Dielectric permittivity and loss values were sensitive to temperature and composition variations. Magnetic and magnetoelectric properties of the xBNKT-(100-x)NCF composites have been investigated. Ions diffusion and chemical reaction between BNKT and ferrite phases cause microstructural and structural variations that are responsible for moving away from the saturation magnetization from those calculated. Moreover, microstructural evolution controls the magnetoelectric properties of these lead-free composites.

Automating a Reverse Osmosis Process to Improve Its Output Yield

Magnetic nanoparticles of Cobalt Nickel Ferrite (Co 1-x Ni x Fe 2 O 4 ) have been synthesized by the co-precipitation method with various concentrations of moles of Ni 2+ as a constituent in Co 1-x Ni x Fe 2 O 4 (x = 0.25, 0.50 and 0.75). The Co 1-x Ni x Fe 2 O 4 structured shows the single phase of crystal was formed with a cubic spinel structure. The crystallite size estimated using the Scherer formula was found that the crystallite size decreased with increasing concentration of Ni 2+ . The samples with various concentration of Ni 2+ showed coercivity and saturation magnetization was decreased by the increasing of concentration of Ni 2+ .

Dysprosium substituted nickel cobalt ferrite nanomaterials and their composites with reduced graphene oxide for photocatalysis

High-quality nanostructure of dysprosium substituted nickel–cobalt ferrite and their composite with reduced graphene oxide (rGO) were synthesized. The structuraland photocatalytic properties of prepared samples were studied. The XRD and FTIR analysis confirmed the FCC spinel structure. The calculated average crystallite size of nanoparticles was around 7.8 nm. The bandgap energy of synthesized composition was found to be 2.27 eV. The uniform dispersion of nanoparticles on the graphene nanosheets were confirmed by the FESEM analysis. The photocatalytic efficiency of nanoparticles and their composites with rGO was studied for degradation of methylene blue (MB) under visible light irradiation. It was found that nanocomposite exhibited high photocatalytic activity (72.7%) as compared to Dy+3 substituted Ni-Co ferrite nanoparticles (52.4%). This enhanced photocatalytic activity can be attributed to the presence of graphene, which enhances the stability of nanocomposite and reduces the recombination of charge carriers.

Magnetic transformation of Zn‑substituted Ni–Co ferrite nanoparticles

A series of ferrite samples with the compositional formula, Ni0.2ZnxCo0.8−xFe2O4 (x = 0.0, 0.2, 0.4, 0.6 and 0.8), was prepared using the citrate-based sol–gel method for the better understanding of zinc doping on the structural and magnetic properties. X-ray diffraction (XRD) studies of the samples showed single-phase ferrite cubic structure without any secondary phases, with the average crystallite size D = 103–130 nm for the samples heat-treated at 950 °C. TEM micrograph shows nearly sphere-shaped particles with particle size consistent with the XRD results. The lattice parameter increased linearly with increasing Zn2+ ion content. Fourier transform infrared (FT-IR) measurements also confirm the formation of the cubic spinel structure of ferrite. The ferrite samples were observed by scanning electron microscopy (SEM) to be spherical nanoparticles. The surface morphology and stoichiometric ratio of the compositional elements were analyzed by scanning electron microscopy equipped with energy-dispersive spectroscopy (EDS). EDS showed that the elemental ratios were stoichiometric. The static magnetism of the magnetometer was studied by using a vibrating sample magnetometer (VSM). An examination of the magnetic properties revealed an increase in saturation magnetization with increasing Zn concentration up to x = 0.2 and a decrease thereafter. These results could be explained using Neel’s collinear two-sub-lattice model and three-sub-lattice non-collinear model suggested by Yafet and Kittel. The magnetic cubic anisotropy constant determined by the law of approach to saturation decreased with increasing Zn content. For Zn-substituted Ni–Co ferrites, the magnetic properties decrease obviously with the increase in Zn2+ ion content. This rapid decrease in magnetic properties reveals that the magnetic properties of Zn-substituted nickel–cobalt ferrite have realized the transition from hard magnetism to soft magnetism. The smaller coercivity value confirms that soft ferrite has been obtained. Meanwhile, this transition from hard magnetism to soft magnetism can be used as a potential high-frequency soft magnetic material.

Structural, morphological and magnetic properties of Ni–Co ferrites by the Mn2+ ions substitution

Manganese substituted nickel–cobalt ferrite nanoparticles having the basic composition Ni0.2MnxCo0.8−xFe2O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4) were synthesized using sol–gel auto combustion method. The effect of Mn substitution on structural and magnetic properties of nickel–cobalt ferrite has been studied. All the prepared samples show that the single-phase cubic spinel structure by X-ray diffraction. The average microcrystalline size of the prepared samples is about 50 nm calculated by Scherrer equation. With the increase of Mn content, the lattice constant decreases first and then increases for the prepared samples. Fourier transform infrared measurements also confirm the formation of the cubic spinel structure of ferrite. The absorption peak of the Fe–O bond at tetrahedral position shifted to the low frequency with the increase of manganese ion content. By transmission electron microscope observation of the preparation of samples with spherical cube crystallite particles. Energy dispersive X-ray confirmed that the synthesis with pure phase and structure of ferrite, and successfully realized the Mn2+ doping. Vibration sample magnetometer measurement confirm that the Ni0.2MnxCo0.8−xFe2O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4) nanoparticles have ferromagnetic behavior. It is observed that the saturation magnetization (Ms), remanent magnetization (Mr), rectangular ratio (Mr/Ms) and magnetic moment are decreasing with the increase of manganese ion content. The prepared ferrites have high coercivity, and the decrease of coercivity of samples is due to excessive Mn substitution. At the same time, the magnetization is expected to decrease because of the conversion of equivalent amounts of Fe3+ (5 µB) to Fe2+ (4 µB).

Assessing the magnetic, cytotoxic and photocatalytic influence of incorporating Yb3+ or Pr3+ ions in cobalt–nickel ferrite

Yb3+- and Pr3+-substituted cobalt–nickel ferrite nanoparticles were prepared through a sol–gel auto-combustion procedure and the effects on the cytotoxic, photocatalytic and magnetic characteristics of the resulting compounds were evaluated. As an initial step, the structure, morphology and magnetic properties of the produced particles were assessed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), UV–visible diffuse reflectance spectroscopy (DRS), photoluminescence (PL), and vibrating sample magnetometery (VSM) techniques. The crystalline size and nanoparticles size of prepared nanostructures was in the range of 100–180 and 90–220 nm based on XRD and SEM results. Using the XRD results it was found that the product had a spinel cobalt–nickel ferrite phase structure, also containing some PrFeO3 and YbFeO3 phases as impurities. VSM results exhibited that Co0.5Ni0.5Pr0.1Fe1.9O4 has higher magnetic parameters than Co0.5Ni0.5Yb0.1Fe1.9O4, yet but the latter enjoys enhanced photocatalytic activity in degrading methyl orange (MO) under ultraviolet (UV) light irradiation.

First order reversal curve analysis of cobalt-nickel ferrite

Abstract In this paper Co1-xNixFe2O4 in which x ranging from 0.0 to 1.0 with 0.2 intervals was prepared with different particle size using a co-precipitation method. A single phase cubic spinel structure with an average crystallite size between 24 and 34 nm was obtained. X-ray diffraction, fourier transform infrared spectroscopy, field emission scanning electron microscopy and vibration sample magnetometer were used to characterize the samples. The energy dispersive X-ray analysis was in good agreement with the nominal composition. It was found that the functional groups of Co-Ni spinel ferrite were formed during the combustion process. It was found that by substitution of nickel cation in cobalt ferrite, the saturation magnetization and the coercivity decreased from 52.70 emu/g and 1673 Oe to 22.11 emu/g and 134 Oe, respectively. First order reversal curves were employed to map the magneto-static interactions and coercivity distributions as a function of nickel concentration. Adding nickel shifts the switching field distribution to the lower field thereby softening the samples. The ratio of reversibility increases with an increase in nickel content due to increase in the percentage of superparamagnetism.

The Influence of Mechanical Stresses on the Magnetic Properties of NiFe2O4 and CoFe2O4 Films

We have studied the influence of mechanical stresses on the magnetic properties of nickel ferrite (NiFev) and cobalt ferrite (CoFe2O4) films deposited on sapphire substrates with a- and c-oriented step terrace nanostructures. It is established that compressive stresses favor enhancement of the coercive field in thin ferrite films in the strain direction. Films of magnetically soft nickel ferrite with a room-temperature coercive field of 32.5 mT were obtained.

Cobalt-Based Ferrites Characterization Using Two Different Terahertz Time-Domain Spectrometers

We report an experimental study of the electrical properties of manganese cobalt (MnCo) and nickel cobalt (NiCo) ferrites in the terahertz (THz) frequency band. The study is motivated by the potential of MnCo, NiCo, and other magnetic ceramics for the fabrication of active and passive devices for THz wave communications. Using two different terahertz (THz) time-domain spectroscopy systems, we characterized the optical constants of cobalt ferrites doped with manganese and nickel in the technologically important 0.2–1 THz frequency band. The MnCo and NiCo ferrites investigated in our study exhibit a lower refractive index and absorption coefficient in the 0.2–1 THz frequency band than commercial strontium ferrite. We observed that using different valency ion oxide leads to a sudden change of the refractive index as a function of sample stoichiometries. Our experimental results provide evidence that microwave ferrite technology can be extended to the THz frequency band.

Self-assembly of multiferroic core-shell composites using DNA functionalized nanoparticles

Ferrite-ferroelectric core-shell nanoparticles were prepared by deoxyribonucleic acid (DNA) assisted self-assembly and the strained mediated magneto-electric (ME) interactions between the ferroic phases were studied. The nanoparticle type and size were varied and the DNA linker sequence was also varied. Two kinds of particles, one with 600 nm barium titanate (BTO) core and 200 nm nickel ferrite (NFO) shell and another with 200 nm BTO core and 50 nm nickel cobalt ferrite (NCFO) shell were prepared. The particles were linked by three different oligomeric DNA containing 19, 18 or 30 base pairs. The core–shell structure was evident from electron microscopy and scanning microwave microscopy images. Films and disks of the core-shell particles were assembled in a magnetic field and used for measurements of low frequency ME voltage coefficient (MEVC) and magnet-dielectric effect. The MEVC data on films indicate that particles assembled with DNA with 30 base pairs exhibit the strongest ME coupling suggesting a more fully integrated heterogenous nanocomposite and the weakest interaction for DNA with 18 base pairs. These results indicate that the longer linker region in DNA is the key factor for forming better composites. This result may be due to the irregular shape of the nanoparticles. Longer DNA strands would be able to bridge better generating more linkages. Shorter strands would not able to bridge the irregularly shaped particles as well and therefore result in linkages and less heterogeneity in the composites.

Magnetic micro scavengers: highly porous Ni1−xCoxFe2O4 microcubes for efficient disintegration of nitrophenol

The fabrication of functional materials in patterned morphology is focused to obtain remarkable physiognomies of the materials for certain applications. Instead of randomly distributed agglomerated nanoparticles, it is highly desirable to arrange them in a motif, as this directed formation of nanomaterials can have a substantial influence on their performance and activity in various applications. With this perspective, MOF derived hollow cubes of nickel cobalt ferrites have been synthesized via a facile process using sacrificial templates at 600 °C. Microcubes, composed of tiny grains in a size range from 10 nm ± 2 nm were obtained in pure form as a polycrystalline material. The high specific surface area (1185 m2 g−1) and mesoporous nature of hollow cubic ferrites were found to be excellent adsorbents for nitrophenol at room temperature. The equilibrium quantity of adsorbed nitrophenol was calculated as 47 mg g−1 ferrite, accomplished in 7 min. Their large surface area, mesopores and hollow nature, in combination with controlled size distribution of grains, have enabled this remarkable utilization of nanoferrites for removal of nitrophenol from water.

Study of gamma ray energy absorption and exposure buildup factors for ferrites by geometric progression fitting method

ABSTRACTThe gamma ray energy absorption and exposure buildup factors (EABF and EBF) were calculated for ferrites such as cobalt ferrite (CoFe2O4), zinc ferrite (ZnFe2O4), nickel ferrite (NiFe2O4) and magnesium ferrite (MgFe2O4) using five parametric geometric progression (G-P fitting) formula in the energy range 0.015–15.00 MeV up to the penetration depth 40 mean free path (mfp). The obtained data of absorption and exposure buildup factors have been studied as a function of incident photon energy and penetration depth. The obtained EABF and EBF data are useful for radiation dosimetry and radiation therapy.

Modulation in magnetic exchange interaction, core shell structure and Hopkinson’s peak with chromium substitution into Ni0.75Co0.25Fe2O4 nano particles

The ever growing applications and ever evolving challenges of magnetic nano particles has been motivating the researchers from various disciplines towards this area of magnetic nano particles. Cation substitutional effect on the magnetic structure of the nanoparticles forms a crucial aspect in their applications. Here the environmentally benign auto combustion method was employed to synthesize chromium substituted nickel cobalt ferrite (Ni0.75Co0.25Fe2-xCrxO4; x = 0, 0.10, 0.15) nano particles, from aqueous metal nitrate solutions. Chromium substitution has shown its effect on the structural, magnetic and electrical properties of Ni0.75Co0.25Fe2O4. Structural and phase analysis of the prepared samples show increased phase purity of ferrite sample with increasing Cr substitution. The TEM (Transmission Electron Microscope) image confirms the nano size of the particles, EDS (Energy dispersive X-ray Spectroscopy) has supported the stoichiometry of the prepared samples and FTIR (Fourier-transform infrared spectroscopic) analysis confirms the spinel structure and also suggests cation redistributions with chromium substitution. VSM (Vibrational Sample Magnetometer) is used to study the magnetic properties through magnetic hysteresis (M−H) loop and magnetic Hopkinson effect. All samples show hysteresis and show reduction in magnetic properties with increase in chromium content. The thermo magnetic study shows Hopkinson peak(s) in the magnetization vs. temperature (M−T) graph and also shows variation in the nature of Hopkinson peak with chromium substitution. Possible reasons for the changes in the nature of the peak are discussed.

Paederia foetida Linn. promoted synthesis of CoFe 2 O 4 and NiFe 2 O 4 nanostructures and their photocatalytic efficiency

A facile method of synthesis of cobalt ferrite (CoFe2O4) and nickel ferrite (NiFe2O4) nanoparticles (NPs) was developed using urea as a hydroxylating agent and Paederia foetida Linn. (family: Rubiaceae) leaf extract as a bio-template. The synthesised ferrite NPs were characterised in a detailed manner by powder X-ray diffraction (XRD), transmission electron microscopy, Fourier transform-infrared spectroscopy and vibrating sample magnetometer analysis. The XRD patterns revealed the formation of cubic face-centred phase for both CoFe2O4 and NiFe2O4 NPs. These quasi-spherical particles of CoFe2O4 and NiFe2O4 were shown to have sizes in the range of 10–80 and 5–50 nm, respectively. The photocatalytic activity of metal ferrites was evaluated in H2O2 assisted oxidative degradation of methylene blue (MB) and rhodamine B (RhB) under irradiation of solar light. Both metal ferrite photocatalysts exhibited pronounced activity in degradation of MB and RhB, respectively, but relatively higher activity was observed for NiFe2O4. After completion, the catalysts were recovered using an external magnet. Recycling of these recovered catalysts up to five times showed no noticeable change in the efficiency.

Влияние напряжений на магнитные свойства пленок NiFe-=SUB=-2-=/SUB=-O-=SUB=-4-=/SUB=- и CoFe-=SUB=-2-=/SUB=-O-=SUB=-4-=/SUB=- на сапфире

AbstractWe have studied the influence of mechanical stresses on the magnetic properties of nickel ferrite (NiFev) and cobalt ferrite (CoFe_2O_4) films deposited on sapphire substrates with a - and c -oriented step terrace nanostructures. It is established that compressive stresses favor enhancement of the coercive field in thin ferrite films in the strain direction. Films of magnetically soft nickel ferrite with a room-temperature coercive field of 32.5 mT were obtained.

The interplay between single particle anisotropy and interparticle interactions in ensembles of magnetic nanoparticles.

This paper aims to analyze the competition of single particle anisotropy and interparticle interactions in nanoparticle ensembles using a random anisotropy model. The model is first applied to ideal systems of non-interacting and strongly dipolar interacting ensembles of maghemite nanoparticles. The investigation is then extended to more complex systems of pure cobalt ferrite CoFe2O4 (CFO) and mixed cobalt-nickel ferrite (Co,Ni)Fe2O4 (CNFO) nanoparticles. Both samples were synthetized by the polyol process and exhibit the same particle size (DTEM ≈ 5 nm), but with different interparticle interaction strengths and single particle anisotropy. The implementation of the random anisotropy model allows investigation of the influence of single particle anisotropy and interparticle interactions, and sheds light on their complex interplay as well as on their individual contribution. This analysis is of fundamental importance in order to understand the physics of these systems and to develop technological applications based on concentrated magnetic nanoparticles, where single and collective behaviors coexist.