ZnFe2O4 Sample Research Articles

Structural, Optical and Magnetic Properties of Ni-Zn Ferrite Nanoparticles Prepared by a Microwave Assisted Combustion Method.

Ni-doped ZnFe₂O₄(Ni(x)Zn₁₋xFe₂O₄; x = 0.0 to 0.5) nanoparticles were synthesized by a simple microwave combustion method. The X-ray diffraction confirms the presence of cubic spinel ZnFe₂O₄for all compositions. The lattice parameter decreases with an increase in Ni content resulting in the reduction of lattice strain. High resolution scanning electron microscope images revealed that the as-prepared samples are crystalline with particle size distribution in 40-50 nm range. Optical properties were determined by UV-Visible diffuse reflectance and photoluminescence spectroscopy respectively. The saturation magnetization (Ms) shows the super paramagnetic nature of the sample for x = 0.0-0.2, whereas for x = 0.3-0.5, it shows ferromagnetic nature. The Ms value is 1.638 emu/g for pure ZnFe₂O₄ sample and it increases with increase in Ni content.

A Simple Combustion Synthesis and Optical Studies of Magnetic Zn1-xNi(x)Fe2O4 Nanostructures for Photoelectrochemical Applications.

Ni-doped ZnFe2O4 (Ni(X)Zn1-x,Fe2O4; x = 0.0 to 0.5) nanoparticles were synthesized by simple microwave combustion method. The X-ray diffraction (XRD) confirms that all compositions crystallize with cubic spinel ZnFe2O4. The lattice parameter decreases with increase in Ni content resulting in the reduction of lattice strain. High resolution scanning electron microscope (HR-SEM) and transmission electron microscope (HR-TEM) images revealed that the as-prepared samples are crystalline with particle size distribution in 42-50 nm range. Optical properties were determined by UV-Visible diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy respectively. The saturation magnetization (Ms) shows the superparamagnetic nature of the sample for x = 0.0-0.2, whereas for x = 0.3-0.5, it shows ferromagnetic nature. The Ms value is 1.638 emu/g for pure ZnFe2O4 sample and it increases with increase in Ni content. Photoelectrochemical (PEC) measurements showed a significant increase of photocurrent density with increase in the Ni-dopant, and 0.5% Ni-doped ZnFe2O4 sample was found to show the better photoresponse than the other doping concentrations.

Synthesis of Mn1-xZnxFe2O4 ferrite powder by co-precipitation method

Ferrimagnetic substances referred to as ferrites are ionic crystals whose chemical composition is of the form XFe2 O4 where X signifies a divalent metal. Magnetic Nano sized ferrites have found a significant potential in many applications, such as magnetic recording media, Ferro fluids and radar absorbing coating. Ferrites are widely used in many industrial applications due to their spontaneous magnetization. Soft ferrites of Mn-Zn, Ni-Zn and Mg-Mn are well known for their high magnetic permeability. In the present research work we have prepared fine Mn1-xZnxFe2O4 ferrite powder with varying x concentrations (0.25-0.75) by metal chloride precursors through a co-precipitation technique by pipette drop method using aqueous NaOH solution for comparing their spontaneous magnetization and particle size. The co-precipitation technique is a high way to produce chemically homogeneous powder with fine particle size in nanometers (22.5nm-74.5nm).The effect of x-concentration on the particle size of the Mn(1-x) Zn(x) ferrite has been discussed on the basis of XRD. The crystalline phases have been identified by X-ray diffraction with Cu-Kα radiations. The XRD patterns have verified that the specimen has spinal type structure. The observable peaks are broad since the size of the particles is small. We have concluded that at constants temperature particle size increases with increasing x-concentrations. Effect of different concentrations of x (Zn+2) on the spontaneous magnetization of different Mn(1-x) Zn(x) Fe2O4 sample is determined. We have reached the conclusion that all the samples of Mn(1-x) Zn(x) Fe2 O4 ferrites were magnetic either of low or high magnetization. The maximum spontaneous magnetization and minimum particle size is obtained at x=0.25 (at digestion temperature=65°C).

Effect of Annealing Temperature on the Physical Properties of Zn-ferrite Nanoparticles

Thermally switched cationic exchange in magnetically ordered ZnFe2O4 (ZFO) nanoparticles synthesized via the coprecipitation route has been studied. The ZFO sample synthesized at 343 K and further annealed at 573 K is devoid of any X-ray diffraction (XRD) peak. However, the samples annealed at temperatures 673–973 K show clear XRD peaks indexed to a cubic spinel ferrite. The average crystallite sizes of the ZFO were calculated using Scherrer’s formula and found in the range of 10–16 nm. The lattice parameter of ZFO nanoparticles increased from 8.212 to 8.524 nm as the annealing temperature was raised from 673 to 973 K. Despite the fact that ZFO is antiferromagnetic in bulk, the ZFO nanoparticles annealed at temperatures ≥673 K show a magnetic hysteresis loop. The value of spontaneous magnetization has been decreased from 22 to 16 emu/gm with an increase in the annealing temperature. The electron spin resonance spectra show a single resonance peak with linewidth ranging from 147 to 243 Oe.

Nanocrystalline spinel ferrite (MFe2O4, M = Ni, Co, Mn, Mg, Zn) powders prepared by a simple aloe vera plant-extracted solution hydrothermal route

Nanocrystalline spinel ferrite MFe2O4 (M=Ni, Co, Mn, Mg, Zn) powders were synthesized by a novel hydrothermal method using Fe(acac)3, M(acac)3 (M=Ni, Co, Mn, Mg, Zn) and aloe vera plant extracted solution. The X-ray diffraction and selected-area electron diffraction results indicate that the synthesized nanocrystalline have only spinel structure without the presence of other phase impurities. The crystal structure and morphology of the spinel ferrite powders, as revealed by TEM, show that the NiFe2O4 and CoFe2O4 samples contain nanoparticles, whereas the MnFe2O4 and MgFe2O4 samples consist of many nanoplatelets and nanoparticles. Interestingly, the ZnFe2O4 sample contains plate-like structure of networked nanocrystalline particles. Room temperature magnetization results show a ferromagnetic behavior of the CoFe2O4, MnFe2O4 and MgFe2O4 samples, whereas the samples of NiFe2O4 and ZnFe2O4 exhibit a superparamagnetic behavior.

Preparation and Evaluation of a Photo-Fenton Heterogeneous Catalyst: Spinel-Typed ZnFe2O4

In this study, spinel-typed ZnFe2O4 was synthesized through Sol-Gel method, using fresh egg white as a complexing agent, and characterized by XRD and SEM. Then, the synthesized sample was used as the photo-Fenton heterogeneous catalyst for the discoloration of methyl orange (MO) in solution. The XRD results show that the synthesized sample was pure, only with the spinel structure, when the volume ratio of the fresh egg white/ferric nitrate/zinc nitrate was 2:2:1. And the lowest sintered temperature to obtain the single-phase ZnFe2O4 was 500°C. The SEM results reveal that the ZnFe2O4 crystalline grains presented irregular shapes and desultorily aggregated together, with a average diameter of 150-250nm. The experimental results show that MO could be efficiently discolored in photo-Fenton system of ZnFe2O4 and H2O2, under UV irradiation. MO discoloration ratio increased as H2O2 dosage increasing. The optimum dosage of ZnFe2O4 was 1g/L in this study. With the MO initial concentration increasing, MO discoloration ratio decreased. The ZnFe2O4 sample obtained at 500°C exhibited the optimum MO discoloration ratio. Finally, the mechanism for MO discoloration in the photo-Fenton system was discussed.

Structural and electrical properties of zinc-substituted cobalt ferrite

Polycrystalline samples of Co1−xZnxFe2O4 with stoichiometric proportion (x) varying from 0.0 to 1.0 were prepared through the thermal decomposition of their respective oxalates. The samples were calcined at 1000 °C for 3 h and characterized using X-ray diffraction (XRD) and Mossbauer spectroscopy techniques. The study of the cation distribution using Mossbauer spectroscopy showed that the ions at the tetrahedral site moved to the octahedral site by the addition of zinc and that the system varied from an inverse to a normal spinel structure. The values of the lattice parameter, X-ray density, oxygen parameter, inversion factor and radii of tetrahedral and octahedral sites were calculated using X-ray diffraction data. The temperature dependence of the conductivity showed a definite kink, except for the ZnFe2O4 sample, which can be attributed to the ferromagnetic–paramagnetic transitions. The calculated activation energy in the paramagnetic region was found to be smaller than that in the ferromagnetic region.

Physicochemical properties of fine-particle ZnFe2O4 prepared by spray pyrolysis of nitrate solutions

Fine zinc ferrite (ZnFe2O4) powders uniform in morphology have been prepared by spray pyrolysis of nitrate solutions. Examination by scanning electron microscopy showed that the powders consisted of micron- and submicron-sized polycrystalline spherical particles. The ZnFe2O4 sample prepared by pyrolysis at 1000°C had paramagnetic properties. Its crystal structure was refined by the Rietveld method and was shown to be a partially inverse spinel with a degree of inversion near 15%. According to nitrogen adsorption measurements, the specific surface of the powders was 5.2 m2/g. The electrical conductance of a film produced from fine-particle zinc ferrite was found to be very sensitive to the hydrogen sulfide concentration in air.