Papers by Keyword: Spinel Ferrite

Abstract: Spinel ferrite nanoparticles are potential candidates for multiple biomedical applications. Spinel ferrite nanoparticles have been studied extensively for understanding physical, chemical, electro-optical as well as magnetic properties which are fascinating due to cationic distributions corresponding to tetrahedral sites and octahedral sites in a cubic phase. Biocompatibility and large magnetic moment are basic requirements in spinel ferrite nanoparticles for efficient functioning in specific application purpose. Fe₃O₄ (magnetite) is an important member of spinel ferrite group with high chemical stability and ferrimagetic material property at nanodimension. Superparamagnetic state and biocompatibility of magnetite (Fe₃O₄) spinel ferrite nanoparticle has already been proven. Spinel ferrite magnetite nanoparticles have been developed based on precipitation of iron oxide using ferric and ferrous ions at the ratio 2:1 in alkaline media at and above 100°C. The experimental parameters have been set to synthesize pure and uniformly sized magnetite nanoparticles. No other phases of iron oxides were detected other than magnetite spinel phase in the XRD result. The average crystal size has been determined from XRD peak broadening. Absorption spectra were investigated using UV-Vis Spectrometer and FTIR. Thermal and magnetic measurements were carried out Digital Scanning Calorimeter and SQUID Magnetometer. One sample of the prepared nanoparticles with polymer coating of polyvinyl alcohol has been studied for superparamagnetic nature. Superparamagnetic particles show saturation value of magnetization 51.26 emu/g at 100 K. ZFC-FC curves for two samples with polymer coating of polyvinyl alcohol and hydroxy-propyl methyl cellulose have also been studied. Keywords: Spinel Ferrite, Magnetite, Ferrimagnetism, Transition metal oxide, Superparamagnetism. Statements and declarations Competing Interests: The authors declare that there is no competing financial interest that are related directly or indirectly to the reported work in this paper. Conflict of interest: There is no conflict of interest. Acknowledgements The Authors are grateful to IISER Bhopal, CRF facility for providing instrumentation facility to characterize magnetic properties. We acknowledge thanks to Lovely Professional University for providing us necessary characterization technique for the XRD analysis and thermal analysis.

Abstract: Cobalt ferrite (Cofe₂o₄) particles were synthesized with and without presence of surfactants using a co-precipitation method. Three surfactants Cetyl Tri methyl Ammonium Bromide (CTAB-cationic), Sodium dodecylbenzenesulphonate (anionic), Triton X-100 (nonionic), were used and investigate their effects on the structural and dielectric properties of CoFe₂O₄ particles. The ferrite precursors were first pre calcined in a muffle furnace at 500°C and then calcined at 950^°C. Structural, dielectric and magnetic properties of prepared particles were investigated using X-ray powder diffraction, Dielectric and Low field ac magnetic susceptibility measurement. Phase purity of prepared samples was confirmed by X-ray diffraction. The sample with surfactant Triton X-100 shows the highest values of dielectric constant at low frequency.

Abstract: Six compositions: x = 0.0 to 0.5 of the spinel system Mn1.5(1-x)Ti0.5(1-x)Fe(1+ 1.5x) Li(0.5)x O4 are synthesized by ceramic method. The structural and magnetic properties are studied by means of X-ray diffraction, AC susceptibility, Magnetization and Mossbauer spectroscopy. The study reveals the significance of FeA-O-FeB magnetic linkages in evolution of long range magnetic ordering through rise in Curie temperature and growth of magnetic hyperfine field with increase in x.

Abstract: Manganese doped cobalt nano ferrites were synthesized by co-precipitation method having general formula Co1-xMnxFe2O4 (x =0.0-1.0). These materials are studied to analyze the structural effects on the associated materials properties. The prepared samples were heat treated at 7500 C for two hours. Sintering effect on the structural properties was investigated. The lattice constants of samples were measured from X-rays diffraction data. The (311) peak was used to find crystallites size by the Scherrer formula. Structural morphology was observed by scanning electron microscopy. Variation with temperature in electrical resistivity (DC) and drift mobility were also investigated. The variations with frequency and composition in AC electrical properties of prepared samples were determined. The structural and electrical properties demonstrated firm association. Saturation magnetization, coercivity and remanence of the samples were discussed with the help of sharing of cations within crystals.

Abstract: The nanocrystalline zinc ferrite (ZnFe2O4) powder was synthesized by high energy reactive ball milling (RM) in a planetary mill. As starting materials a mixture of commercial zinc oxide (ZnO) powder and iron oxide (Fe2O3) powder was used. The starting mixture was milled for different periods of time, up to 30 h. The milled powders were annealed for 4 h at 350 oC in order to eliminate the internal stress and to finish the solid state reaction of ferrite formation. Zinc ferrite formation was investigated by X-ray diffraction. The obtained powder has a mean crystallite size of 12 nm after 20 h of milling. Using scanning electron microscopy (SEM) the particle morphology was studied. Particles size range of the powders was also determined using a laser particle size analyser.

Abstract: The electronic structure and magnetic properties of the (Co1-xFex)Tet(CoxFe2-x)OctO4 spinels (x is defined as the degree of inversion) scenario are investigated theoretically from first-principles, using generalized gradient approximation (GGA) method for the systems with strong coulomb correlations, which gives a correct description of the electronic structure. The GGA+U method gives an improved qualitative result compared with the GGA not only for the excited-state properties such as energy gaps but also for the ground-state properties such as magnetic moments and crystal parameters. The nominal valence of the transition metal elements and the ground state structure have been established based on the study of variation of the cation distribution (x=0.0, 0.25, 0.5, 0.75 and 1.0) over the tetrahedral and octahedral sites. The site-preference calculation on bulk systems indicates that Co2+ ions strongly prefer the octahedral B sites, and the electronic structure and magnetic properties of cobalt ferrites highly depend on the cation distributions even though the chemical composition of the compound does not change. The results are in good agreement with the available experimental data and most of the other theoretical results.

Abstract: Ni-Zn spinel ferrite and Cu-doped spinel ferrite were prepared by a conventional ceramic processing method. Microwave absorption, complex permittivity and permeability of the (Ni0.5Zn0.5)Fe2O4 and (Ni0.4Cu0.2Zn0.4)Fe2O4 spinel ferrites within the frequency range of 0.5-18 GHz were investigated. The reflection loss calculation results show that the Ni-Zn spinel ferrite and Cu-doped Ni-Zn spinel ferrite are good electromagnetic wave absorbers in the microwave range. The single layer (Ni0.4Cu0.2Zn0.4)Fe2O4 spinel ferrite absorber with a thickness of 9.2 mm achieved a reflection loss below -10 dB (90% absorption) at 0.5-2.3 GHz, and the minimum value is -35.63 dB at 1.1 GHz. When the first layer and second layer are (Ni0.5Zn0.5)Fe2O4 and (Ni0.4Cu0.2Zn0.4)Fe2O4 spinel ferrites respectively, the laminated absorbers with double spinel ferrite layers with a thickness of 3 mm achieved a reflection loss below -10 dB at 9.9-12.3 GHz, and the minimum value is -35.3 dB at 11.7 GHz.