Kamlesh V. Chandekar; K. Mohan Kant
Abstract
Cobalt ferrite (CoFe2O4) nanoparticles were synthesized by co-precipitation route at 80 °C. X-ray diffraction pattern (XRD) confirmed cubic inverse spinel structure of CoFe2O4 nanoparticles. The average crystallite size of CoFe2O4 nanoparticles estimated by X-ray line profile fitting was 12±2 ...
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Cobalt ferrite (CoFe2O4) nanoparticles were synthesized by co-precipitation route at 80 °C. X-ray diffraction pattern (XRD) confirmed cubic inverse spinel structure of CoFe2O4 nanoparticles. The average crystallite size of CoFe2O4 nanoparticles estimated by X-ray line profile fitting was 12±2 nm for high-intensity peak (311). The particle size, distribution and surface morphology was estimated using Transmission electron microscopy (TEM) with average particle size of 16±2 nm. Raman spectra of CoFe2O4 nanoparticles exhibits phonon modes corresponding to tetrahedral sites (679 cm -1 ) and octahedral sites (465 cm -1 ) respectively. The saturation magnetization Ms for CoFe2O4 sample is found to be 63 and 82 emu/g at 300 K and 10 K respectively. The cubic magnetic anisotropy constant K1 and saturation magnetization Ms are obtained by fitting M versus H isotherm to the saturation approach law. By fitting, K1 and Ms is 2.16 x10 5 J/m 3 and 66 emu/g respectively at 300 K. The cubic magnetic anisotropy constant K1 = 5.49 x10 5 J/m 3 is evaluated at blocking temperature of 144 K. The particle size and L-S coupling is responsible for superparamagnetic behaviour of CoFe2O4 nanoparticles. Fitting of FC curve provides Curie temperature at Tc = 823K using modified Bloch’s law for CoFe2O4 nanoparticles. Tunable particle sizes by controlling the magnetic anisotropy and L-S coupling will tailor magnetic properties and usage in bio-medical applications
Soumya Mukherjee; Manoj Kumar Mitra
Abstract
Multiferroic materials are new class of multi-functional materials which possess both ferro-electric and magnetic properties. This type of material has wide range of applications like semi-conducting to sensors applications. Nanocomposite of equimolar perovskite-spinel is synthesized by chemical ...
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Multiferroic materials are new class of multi-functional materials which possess both ferro-electric and magnetic properties. This type of material has wide range of applications like semi-conducting to sensors applications. Nanocomposite of equimolar perovskite-spinel is synthesized by chemical route by blending of Nickel ferrite as second phase on Bismuth ferrite after heat treatment at 500 °C for 2, 3 and 4 hours soaking period. From the diffractogram data of XRD, the phase, and planes of orientation are analyzed of the synthesized materials. The crystallite size is calculated by Scherrer’s formula. FESEM studies reveal the morphological features having interconnected agglomerates with spherical, irregular polygonal or some elongated shape of the synthesized nanocomposite. FTIR result shows the molecular signature of the nanocrystalline material to verify the M-O coordination. Interplanar spacings and SAED pattern are revealed from HRTEM images which are very close to the experimental findings from XRD phase analysis. UV-VIS analysis is performed in the transmission mode of spectra within the scan range of 200-1100 nm. From the spectra, using Tauc relation band gap is calculated. Band gap are found of the order of 2.847 eV, 2.78 eV, 2.69 eV respectively for 2, 3 and 4 hours soaking period close to semiconducting material. With the increase of soaking time band gap is found to decrease following Arrhenius activation of electronic mobility overwhelming the energy barrier at respective lattice sites. M-H analysis of Nanocomposite at 500 °C for 2 hrs is closer towards ferromagnetic with incomplete loop but for sample at 500 °C for 4hrs it is closer towards superparamagnetic one. The property of this material reflects it has many interesting characteristics suitable for opto-electronic, photo-magnetic devices and other electronic applications.
S. Ravi; A. Kartikeyan
Abstract
Magnetically tunable colloidal nano clusters (CNC’s) have been fabricated using superparamagnetic cobalt doped iron oxide CNCs for the first time. This has the regular interparticle spacing and strongly diffracts light, which is being controlled by an external field. The size of the nanoclusters ...
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Magnetically tunable colloidal nano clusters (CNC’s) have been fabricated using superparamagnetic cobalt doped iron oxide CNCs for the first time. This has the regular interparticle spacing and strongly diffracts light, which is being controlled by an external field. The size of the nanoclusters varies from 10nm–200nm. It reveals that it can be used for wide magnetic tunability. The response to the magnetic field was studied using reflection spectra by varying field sample distance. This shows good response in the UV and visible region. We obtained eight prominent peaks in the UV region which enhances the prosperity of our CNC’s sensing the UV predominately. Hysteresis behavior shows the presence of superparamagnetic nature, which is promising candidate for drug delivery, bioseperation and magnetic resonance imaging.
Ajay Shankar; Sandeep Kumar; Sanjeeve Thakur; Rajni Porwal; R. P. Pant
Abstract
Nanocrystalline NixCo1-xFe2O4 were synthesized and studied for their structural and magnetic properties. The effect of doping ion concentration on lattice parameter, crystallite size and the lattice strain pertaining to the ionic radii has been investigated. Electron microscopy supports the parameters ...
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Nanocrystalline NixCo1-xFe2O4 were synthesized and studied for their structural and magnetic properties. The effect of doping ion concentration on lattice parameter, crystallite size and the lattice strain pertaining to the ionic radii has been investigated. Electron microscopy supports the parameters and gives morphological view of the system. The magnetic measurement reveals the information on the effect of stoichiometry variation in existing superparamagnetism. Further, the spin dynamics and their role on dipolar interactions, extent of superexchange and spin-spin relaxation among nanoparticles have been investigated. Also, an attempt has been made to understand the UV irradiation effect on photosensitive Co 2+ ion on Ni ferrite by in-situ electron spin resonance measurements.
Mandeep Singh; Manish Kumar; Frantisek Stipanek; Pavel Ulbrich; Pavel Svoboda; Eva Santava; M.L. Singla
Abstract
We have synthesized nickel nanoparticles using nickel chloride as a precursor in ethanol using PVP (Poly Vinyl Pyrrolidone) as a surfactant and hydrazine hydrate as reducing agent at 60 °C in a facile manner. The structural analysis showed that particles are face-centered cubic and monodisperse within ...
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We have synthesized nickel nanoparticles using nickel chloride as a precursor in ethanol using PVP (Poly Vinyl Pyrrolidone) as a surfactant and hydrazine hydrate as reducing agent at 60 °C in a facile manner. The structural analysis showed that particles are face-centered cubic and monodisperse within the PVP matrix with average size about 3 nm. The magnetic analysis shows the superparamagnetism of the single-domain nickel nanoparticles with the blocking temperature (Tb) exists around 14 K with clear hysteretic effect observation below this blocking temperature.
