Papers by Keyword: Nickel Ferrite

Abstract: The aim of the present research work was to prepare NiFe₂O₄ nanoparticles using standard wet chemical method namely sol-gel auto-combustion with a view to study them in heat transfer application. The prepared nanoparticles of NiFe₂O₄ were then applied to prepare nanofluid with deionised water as a base fluid. The characterization of the prepared NiFe₂O₄ nanopowder is done by X-ray diffractometer (XRD) technique. The XRD pattern was recorded at room temperature. The analysis of XRD pattern was carried by standard software suggests that prepared nickel ferrite nanopowder possess single phase cubic spinel structure. The lattice constant was obtained by using XRD data reasonably agree with the reported values. The mean size of the particle was estimated through XRD pattern, in which the most intense peak (311) was considered to obtain full width at half maxima (FWHM). The Scherrer formula was used to obtain average crystallite size which was found to be 33 nm. The surface morphology of the prepared NiFe₂O₄nanopowder was studied by means of scanning electron microscopy (SEM) technique. The average grain size determined by linear intercept method was found to be of the order of 40 nm. The SEM image shows formation of spherical grains with some agglomeration. The prepared nanofluid of nickel ferrite was used to estimate thermal conductivity. It was found that, the thermal conductivity of NiFe₂O₄nanofluid was increased compared to deionised water.

Abstract: Wet chemical methods in particular sol-gel auto combustion method play a vital role in governing the size and the shape of the particles. In the present communication, nickel ferrite nanoparticles were prepared by sol-gel auto combustion technique using citric acid as a fuel. The metal nitrate to fuel ratio was chosen as 1:3 using propellant chemistry approach. The nanopowder of the nickel ferrite was prepared at various pH viz. 2, 5, 7 and 9. The obtained nanopowder was annealed at 600°C for 4 h and used for further characterizations. All the samples were structurally characterized by X-ray diffraction and infrared spectroscopy technique. The room temperature XRD pattern reveals the formation of single-phase cubic spinel structure. The lattice constant calculated from XRD data shows dependence of pH values. The Fourier transform infrared spectra show two absorption bands in all the four samples near 400 cm^-1 and 600 cm^-1. However, a slight variation in the absorption band is observed for different pH.

Abstract: Here, we report the synthesis, characterizations and magnetic properties of Ce-Al co-doped nickel ferrite. The samples of pure nickel ferrite ( NiFe₂O₄ ) and Ce-Al doped nickel ferrite (NiFe_1.96Ce_0.02Al_0.02O₄ ) were prepared in nanocrystalline form using sol-gel auto combustion method. X-ray diffraction technique was employed to know the phase purity and for the determination of structural properties. Examination of XRD pattern shows the presence of those reflections which belongs to cubic spinel structure indicating the formation of single phase cubic spinel structure. The lattice constant, X-ray density and other structural parameters were determined from the XRD data and the influence of Al-Ce doping is studied. It is observed from structural studies that the lattice constant and other structural parameters increased. as compared to pure nickel ferrite. The magnetic properties were studied at room temperature using pulsed field hysteresis loop technique. The M-H plot show typical ferrimagnetic behaviour from which the values of saturation magnetization, coercivity and remanence magnetization were obtained. The magnetic data suggests that, Al-Ce co-doping strongly influences the magnetic properties also. The doping of Ce-Al in nickel ferrite leads to canted spin structure. The observed magnetic bahaviour of Ce-Al doped nickel ferrite is explained on the basis of Neel’s and Yafet-Kittel model.

Abstract: Nanostructured materials have attracted considerable attention in recent years because of their unique and amazing properties. With a high surface activity due to their small particle size, enormous surface area and specific mechanical properties, it has been used for various engineering purposes including chemical, mechanical and civil engineering applications. The rapid development of nanostructured materials and nanotechnology will change the traditional processes of fabrication and applications of construction materials. nanosized materials can be used in construction industry to produce lighter and stronger structural composites such as modified steel. The present work introduces a novel idea for the production of metallic alloys from nanosized nickel ferrites using powder technique routes. nanosized nickel ferrite (50 nm) is being used as starting material for the production of metallic alloy containing iron and nickel. The prepared alloys were characterized physically and chemically through X-ray diffraction and optical microscope. The composition of these alloys is often a key factor to control the mechanical, chemical and physical properties of the synthesized alloys. The reduction processes take place in a stepwise manner via the formation of a series of intermediate oxides. The microstructures of the produced alloy together with the kinetics data obtained from reduction process were used to elucidate the reduction mechanism under isothermal conditions.

Abstract: Different ways to prepare nanosized nickel ferrite particles have been developed. Typical solid state reaction routes including high temperature sintering, mechanical alloying, self-propagating high temperature synthesis and wet chemistry methods including co-precipitation, sol-gel, hydrothermal synthesis are briefly reviewed and compared by focusing on the particle size control.

Abstract: The influence of particle size of the load in the structure and morphology of the composite is an important factor in their final properties. This study will evaluate the behavior of the load of nickel ferrite calcined at different temperatures (700, 900 and 1200 ° C) with the polyamide matrix 6. In the preparation the polymer matrix was previously been dried in a vacuum oven at 80 ° C/48hs for eliminating humidity, and then the load was incorporated in the form of powders calcined at three temperatures in the mass concentration of 50%. Thereafter, the mixture was compressed to obtain composites, which were characterized by XRD and SEM. The results show XRD characteristic peaks of nickel ferrite and polyamide 6, showing that the calcination caused an increase in crystallinity of the load. SEM results show that the calcination caused an increase in the size of the agglomerates of the load, favoring significant changes in the morphology of the composite.

Abstract: Abstract: The magnetic nano-particles of nickel ferrite were synthesized successfully by sol-gel auto-combustion method using high purity metal nitrates and citric acid as chelating agent. The as prepared powder of nickel ferrite was sintered at 5500C for 5 hr to obtain good crystalline phase and was used for further study. The X-ray diffraction technique was employed to confirm the single phase formation of nickel ferrite nano-particles. The X-ray diffraction pattern shows the Bragg’s peak which belongs to cubic spinel structure. The values of lattice constant, X-ray density, oxygen parameter and radii of tetrahedral and octahedral sites were calculated from XRD data. The average crystallite size was estimated using Scherrer’s formula and found to be 6 nm. The temperature dependence of the electrical conductivity plot shows the kink, which can be attributed to ferromagnetic-paramagnetic transition. The activation energy obtained from resistivity plots in paramagnetic region is found to be more than that in ferrimagnetic region. The conduction mechanism in these nickel ferrite nano-particles has been discussed on the basis of hopping of electrons.

Abstract: Nanocrystalline Ga doped nickel ferrite [(NiFe_2-xGa_xO₄ (x=0.0, 0.1, 0.3, 0.5 and 0.7)] powders have been synthesized by sol-gel auto-ignition method and the effect of non-magnetic gadillum content on the nanosize particles and magnetic properties has been studied. The X-ray diffraction (XRD) revealed that the powders obtained are single phase with spinel structure. The calculated grain size from XRD data have been verified using transmission electron microscopy (TEM). TEM photograph shows that the powders consist of nanometer sized grain. The size of nanoparticles decreases as the non magnetic Ga content increases. Magnetic hysteresis loops were measured at room temperature with maximum applied magnetic field of 20 KOe. As Ga content increases, the measured magnetic hysteresis curves became border and saturation magnetization (M_S) increased up to x= 0.3 and further increase of x leads the magnetization to decrease. The results are explained according to the assumed cation distribution.

Abstract: Metallic oxide materials with AB₂O₄ structure are very interesting for technological applications. Nickel ferrite (NiFe₂O₄), for example, attracts considerable attention due to its chemical stability and mechanical hardness. These characteristics make it a suitable material for magnetic and magneto-optical applications. The properties of NiFe₂O₄ have a strong dependence on the crystallite size and microstructure. Due to this dependence, it is necessary to develop effective methods that allow controlling these variables. The aim of this work is to investigate the effect of time, temperature of isothermal treatment and choice of organic precursor during the production of NiFe₂O₄ samples employing the proteic sol-gel method have on crystallite size and microstructure. Two kinds of organic precursors were used: coconut water and pectin extracted from aple peel. Temperatures of 873 and 1173 K; 2, 4, 6, 8, 24 and 30 hours of isothermal treatment were also used. The samples produced were analyzed employing X-ray Diffraction.

Abstract: This paper aims to synthesize and characterize nanosized nickel and zinc ferrites (NiFe₂O₄ and ZnFe₂O₄) samples by a combustion reaction method, using glycine as fuel. The performance in HT-WGRS reaction the samples was investigated. The results showed that the combustion reaction was effective in the production of major phases of the spinel ferrite (crystallite sizes of 44 and 27 nm) and presence of the secondary phases, such as Ni and ZnO, with surface area 3 and 115 m²/g for NiFe₂O₄ and ZnFe₂O₄, respectively. HT-WGSR activity was achieved (80%) to NiFe₂O₄ ferrite in the temperature range of 300 - 500°C.