Magnetic Properties of ZnFe2O4 Nanoparticles Synthesized by Starch-Assisted Sol-Gel Auto-combustion Method

In this paper, ZnFe2O4 spinel ferrite nanoparticles with different grain sizes at different annealing temperatures have been synthesized using the starch-assisted sol-gel auto-combustion method. The synthesized nanoparticles were characterized by conventional powder X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and vibrating sample magnetometer. The X-ray diffraction (XRD) patterns demonstrated that the ZnFe2O4 nanoparticles consist of single-phase spinel structure with crystallite sizes 4.81, 8.72, 12.06, 29.32, and 72.60 nm annealed at 400, 600, 800, 1000, and 1200 A degrees C, respectively. Field emission scanning electron microscopy reveals that particles are of spherical morphology at lower annealing temperature and hexagonal-like morphology at higher temperature. An infrared spectroscopy study shows the presence of two principal absorption bands in the frequency range around 525 cm(-1) (nu (1)) and around 350 cm(-1) (nu (2)), which indicate the presence of tetrahedral and octahedral group complexes, respectively, within the spinel ferrite nanoparticles. Raman spectroscopy study also indicated the change in octahedral and tetrahedral site-related Raman modes in zinc ferrite nanoparticles with change of particle size. The nanocrystalline ZnFe2O4 samples (4.81, 8.72, 12.06, 29.32 nm) show ferrimagnetic behavior, and bulk sample (72.60 nm) shows paramagnetic behavior. This change in magnetic behavior is due to change of cation distribution in ZnFe2O4 nanoparticles with decrease of particle size.Project Excellent Teams at Materials Research Centre, Brno University of Technology [CZ.1.07/2.3.00/30.0005, CZ.1.07/2.3.00/30.0039]; project Centre of Polymer Systems at Tomas Bata University in Zlin, Czech Republic [CZ.1.05/2.1.00/03.0111

Magnetic Properties of Dysprosium-Doped Cobalt Ferrite Nanoparticles Synthesized by Starch-Assisted Sol-Gel Auto-combustion Method

Dysprosium-substituted cobalt ferrite nanoparticles with composition of CoFe2−xDyxO4 (x = 0 − 0.1 in a step of 0.025) were synthesized by starch-assisted sol–gel auto-combustion method. The effect of Dy3+ cation substitution on structural and magnetic properties of cobalt ferrite nanoparticles was investigated. Powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, infrared spectroscopy (IR), X-ray photoelectron spectroscopy and vibrating sample magnetometer (VSM) were employed to characterize the physical properties of these ferrite nanoparticles. XRD pattern reveals the formation of cubic spinel ferrite with the signature of DyFeO3 phases for x ≥ 0.05. An infrared spectroscopy study shows the presence of two absorption bands in the frequency range around 560 cm−1 (ν1) and around 380 cm−1 (ν2), which indicate the presence of tetrahedral and octahedral group complexes, respectively, within the spinel ferrite nanoparticles. FE-SEM analysis indicated the formation of nanosized particles (5 −15 nm) with spherical morphology. Vibrating sample magnetometer was employed to probe the magnetic properties of the samples at room temperature. It was observed that rare earth ion dopant, crystallite size and foreign phase DyFeO3 affect the magnetic properties of cobalt ferrite nanoparticles. © 2015, Springer Science+Business Media New York.Materials Research Centre, Brno University of Technology [CZ.1.07/2.3.00/30.0005, CZ.1.07/2.3.00/30.0039]; Centre of Polymer Systems at Tomas Bata University in Zlin, Czech Republic [CZ.1.05/2.1.00/03.0111

Structural and magnetic properties of CoFe2O4 nanoparticles synthesized by starch-assisted sol-gel auto-combustion method in air, argon, nitrogen and vacuum atmospheres

In the present work, structural and magnetic properties of CoFe2O4 nanoparticles synthesized by starch-assisted sol-gel auto-combustion method in air, argon, nitrogen and vacuum atmospheres were investigated. The particle size, shape, crystal structure and magnetic properties of synthesized ferrite nanoparticles were investigated by powder X-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectrometer, Fourier transform infrared spectroscopy (FTIR) and a vibrating sample magnetometer (VSM). The FE-SEM micrographs indicate the octahedron-like cobalt ferrite nanoparticles formation in air atmosphere; however, spherical nanoparticles were formed in argon, nitrogen and vacuum atmospheres. An infrared spectroscopy study showed the presence of two absorption bands in the frequency range around 560 cm(-1) (nu(1)) and around 340 cm(-1) (nu(2)) which indicated the presence of tetrahedral and octahedral group complexes, respectively, within the spinel lattice. Room temperature magnetization measurements showed that the saturation magnetization (M-s) and coercivity (H-c) were influenced by cobalt ferrite formation atmosphere, i.e., air, argon, nitrogen and vacuum.Materials Research Centre, Brno University of Technology [CZ.1.07/2.3.00/30.0005, CZ.1.07/2.3.00/30.0039]; Centre of Polymer Systems at Tomas Bata University in Zlin, Czech Republic [CZ.1.05/2.1.00/03.0111