Synthesis and Magnetic Properties of Ni‐Cu Nano‐Magnetic Ceramics

Abstract

Nano-cermics of Nij.x Cux Fe 2 0 4 (0 < X < 1) ferrites were synthesized by citrate -gel auto-combustion technique. The crystal structure was investigated by X-ray diffraction (XRD). The values of lattice parameter and X-ray density have been calculated from XRD data. The octahedral (de) and tetrahedral (d A ) sites were also calculated. Magnetic properties of nanoceramics are investigated by Vibrating Sample Magnetometer (VSM) in the range of 20KO e at room temperature. The Saturation Magnetization (M s ) and Magnetic Moment (ps) were calculated and shows a decrease with increase of Cu substitution in Ni nano-ferrites. INTRODUCTIONMagnetic materials such as Spinel ferrites with chemical formula MFe 2 04 (where M stands for divalent ions of the transition metal elements such as Ni, Cu, Co, Zn, Mg, Fe, Cd and Mn.) have tremendous commercial viability as they have very good magnetic and electrical properties. The chemical composition, preparation methods, sintering temperature, nature of the additives and the choice of cations along with Fe 2+ and Fe 3+ ions and their distribution between tetrahedral (A-site) and octahedral (B-site) sites of the spinel lattice decide the structural and magnetic properties of these Spinel ferrites 1 .There are plenty of applications for Magnetic ferrites such as Ni-ferrite (NiFe 2 0 4 ) in the areas of biomedical, magnetic ferrofluids, microwave absorption, repulsive suspension for levitated railway systems, gas sensing capabilities, etc. ' \ Synthesising ferrite nanocrystals with various metals, such as chromium, copper, manganese, and zinc results the increase of some of their electric or magnetic properties '. Substituting copper in nickel ferrite results in the alteration of properties of nickel ferrite which is used in many device applications and this is considered one important class of spinel ferrites 7 , The nickel-copper ferrite has possible applications in nanoscience and technology. That is reason researchers in the field of electronics are vigorously investigating the design of superstructures comprised of magnetically ordered arrays to enhance the sensitivity in magnetic sensors. Nickel-copper ferrites play considerably significant role among magnetic materials because of their high electrical resistivity, high saturation magnetization and high magnetic permeability

Magnetic properties and potential barrier between crystallites model of MgGa2-xFexO4 ceramics

“…The dielectric permittivity of these samples may be related to the space-charge polarization since higher conductivity grains are separated by insulating grain boundaries which produces localized accumulation of charge under the influence of an alternated electric field [15]. According to Maxwell and Wagner two-layer model, spacecharge polarization is due to the inhomogeneous dielectric structure of the material [15,16]. A similar variation of the dielectric constant with frequency was observed in the case of ZnFe 2 O, MnFe 2 O 4 [17], Zn x Cu 1-x Fe 2 O 4 and Mn x Cu 1-x Fe 2 O 4 [18] ferrite systems.…”

“…It is seen that the value of the dielectric constant is very high at low frequencies and decreases with increasing frequency, and then at higher frequency they become almost constant. The decrease in dielectric constant value with increasing frequency is attributed to the fact that the electron exchange between Fe 2+ and Fe 3+ ions cannot follow the change of the external applied field beyond certain frequency [16,20]. At low frequencies, grain boundaries are more effective than grain electrical conduction.…”

“…At low frequencies, grain boundaries are more effective than grain electrical conduction. The higher value of dielectric constant at low frequency is due to voids, dislocations and other defects [16,20]. In the high frequency range, which corresponds to low resistivity due to the grains, a small energy is needed for electron transfer between Fe 2+ and Fe 3+ ions in grains and accompanied by a small eddy current and hence a decrease in the energy loss in all samples [16,20].…”