Cu1−xZnxFe2O4/SiO2 (CZF/SiO2) (x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) nanocomposites were synthesized by a citric acid assisted sol–gel process and a modified Stöber method. Particle formation and evolution ...of the structural, morphological, optical and magnetic properties were investigated by Thermal analysis (TGA), X-ray powder diffractometry (XRD), high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HR-TEM)), Fourier transform infrared spectroscopy (FT-IR), UV–visible diffuse reflectance spectra (DRS), and magnetic susceptibility measurements (VSM). Optical properties of Cu–Zn ferrite nanoparticles (NPs) were improved by using silica (SiO2) shell. CZF/SiO2 nanocomposites were evaluated for their magnetic and optical characteristics. The direct optical band gap (Eg) value was calculated as 1.70eV. The Eg of CZF/SiO2 nanocomposites is found to increase as the Zn content rises. Moreover, silica coating enhances the band gap of the nanocomposites. These properties of CZF/SiO2 nanocomposites make them promising candidates for magneto-optical nano-device applications.
A magnetic nanocomposite was generated by the sol–gel auto-combustion method in the presence of 1-methyl-2-pyrrolidone, a functional solvent. The temperature-dependent magnetic properties of the ...CoFe2O4 nanoparticles have been extensively studied in the temperature range of 10–400K and magnetic fields up to 80kOe. Zero field cooled (ZFC) and field cooled (FC) curves indicate that the blocking temperature (TB) of the CoFe2O4 nanoparticles is above 400K. It was found from M–H curves that the low temperature saturation magnetization values are higher than bulk value of CoFe2O4. The saturation magnetization (Ms), remanence magnetization (Mr), reduced remanent magnetization (Mr/Ms) and coercive field (Hc) values decrease with increasing temperature. The Mr/Ms value of 0.75 at 10K indicates that the CoFe2O4 nanoparticles used in this work have, as expected, cubic magnetocrystalline anisotropy according to the Stoner–Wohlfarth model. T1/2 dependence of the coercive field was observed in the temperature range of 10–400K according to Kneller's law. The extrapolated TB and the zero-temperature coercive field values calculated according to Kneller's law are almost 427K and 13.2kOe, respectively. The room temperature Hc value is higher than that of the previously reported room temperature bulk values. The effective magnetic anisotropy constant (Keff) was calculated as about 0.23×106erg/cm3 which is lower than that of the bulk value obtained due to disordered surface spins.
Annealed cobalt inverse spinel-type ferrite nanoparticles were synthesized using polyethylene glycol assisted co-precipitation. The structure, magnetic properties and effect of annealing temperature ...was investigated in detail. Saturation magnetization, coercivity and remanence magnetization were observed to decrease with increasing temperature. The magnetic hysteresis curves supported the proposition that the CoFe
2
O
4
nanoparticles showed ferromagnetic character from 10 to 400 K. Magnetization measurements showed the blocking temperature to be higher than 400 K. Unsaturated magnetization behavior suggested the existence of disordered spins in the surface layer of the CoFe
2
O
4
nanoparticles.
For the synthesis of Fe sub(3)O sub(4)ween20 nanocomposite, two surfactants (Tween20 and oleic acid) were used to overcome the aggregation. The nanoparticles were used to prepare a water-based Fe ...sub(3)O sub(4)ween20 nanocomposite using oleic acid and Tween20 as surfactants ( Fe sub(3)O sub(4) colloidal superparticles were developed by introducing Tween20 as a surface modification agent to maintain the colloidal stability of the F e sub(3)O sub(4) superparamagnetic nanoparticles (SPION)). Vaseline and the synthesized iron oleate were used for the polyol synthesis of Fe sub(3)O sub(4)ween20 nanocomposite. The product has superparamagnetic property. Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA) proved the presence of both surfactants on the surface of the Fe sub(3)O sub(4) nanoparticles. The product may have potential use in magnetic resonance imaging and hyperthermia.
Nanoparticles (NPs) of CoFe sub(2)O sub(4), which is a well-known spinel ferrite and hard magnetic material with very high cubic magnetocrystalline anisotropy, were synthesized by co-precipitation ...method. The effect of different molecular weights of polyethyleneglycol (PEG) on the magnetic properties and crystallite size of CoFe sub(2)O sub(4) NPs was investigated by using PEG-400, PEG-10.000 and, PEG-20.000. Crystalline structure and size of CoFe sub(2)O sub(4) NPs were studied using X-ray diffraction (XRD). The VSM studies showed that the saturation magnetization (M sub(s )) and coercivity (H sub(c )) of the CoFe sub(2)O sub(4) NPs depend on molecular weight of PEG.
For the synthesis of Fe
3
O
4
@Tween20 nanocomposite, two surfactants (Tween20 and oleic acid) were used to overcome the aggregation. The nanoparticles were used to prepare a water-based Fe
3
O
4
...@Tween20 nanocomposite using oleic acid and Tween20 as surfactants ( Fe
3
O
4
colloidal superparticles were developed by introducing Tween20 as a surface modification agent to maintain the colloidal stability of the
F
e
3
O
4
superparamagnetic nanoparticles (SPION)). Vaseline and the synthesized iron oleate were used for the polyol synthesis of Fe
3
O
4
@Tween20 nanocomposite. The product has superparamagnetic property. Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA) proved the presence of both surfactants on the surface of the Fe
3
O
4
nanoparticles. The product may have potential use in magnetic resonance imaging and hyperthermia.
Polyaniline–MnFe
2
O
4
nanocomposite was successfully synthesized by using 1-butyl-3-methyl-imidazolium bromide (BMIMBr) as ionic liquid and cetyl trimethylammonium bromide (CTAB) as surfactant via ...in situ polymerization. Structural, morphological, spectroscopic and magnetic properties were investigated by transmission electron microscopy, X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM) respectively. The presence of polyaniline, BMIMBr and CTAB on the surface of the MnFe
2
O
4
nanoparticles was confirmed with FT-IR and chemical purity of the product was proved by XRD. The nonmagnetic coating was significantly observed to change the magnetic properties of the product. The magnetic properties such as saturation magnetization, coercivity and remanence magnetization are seen to increase as the temperature decreases. The magnetization curves verify that the sample has ferromagnetic behavior in the temperature range of 10–400 K. Magnetic measurements revealed that product has uniaxial anisotropy instead of expected cubic anisotropy according to the Stoner–Wohlfarth model.
Nanoparticles (NPs) of CoFe
2
O
4
, which is a well-known spinel ferrite and hard magnetic material with very high cubic magnetocrystalline anisotropy, were synthesized by co-precipitation method. ...The effect of different molecular weights of polyethyleneglycol (PEG) on the magnetic properties and crystallite size of CoFe
2
O
4
NPs was investigated by using PEG-400, PEG-10.000 and, PEG-20.000. Crystalline structure and size of CoFe
2
O
4
NPs were studied using X-ray diffraction (XRD). The VSM studies showed that the saturation magnetization (
M
s
) and coercivity (
H
c
) of the CoFe
2
O
4
NPs depend on molecular weight of PEG.
