Effect of Zn Substitution on the Magnetic Properties of Cobalt Ferrite Nano Particles Prepared Via Sol-Gel Route

Zinc substituted cobalt ferrite nanoparticles (CoxZn1-xFe2O4, with x = 0.0, 0.2, 0.4, 0.8 and 1.0) were prepared via sol-gel route and the effect of zinc concentration on saturation magnetization and lattice parameter were investigated. The particle sizes of the as obtained samples were found to be ~10 nm which increases upto ~92 nm on annealing at 1000oC. The frequency bands near 564-588 cm-1 and 425-442 cm-1 are assigned to the tetrahedral and octahedral clusters which confirm the presence of M-O stretching band in ferrites. The unit cell parameter ‘a’ increases linearly with increasing concentration of zinc due to larger ionic radii of Zn2+ ion . It was found that this substitution allows tunable changes in the magnetic properties of cobalt ferrite. Interestingly, saturation magnetization first increases upto x = 0.4 and then decreases for higher Zn substitution, thus tunable changes in magnetic properties of cobalt ferrite are possible. Source of such behaviour could be the variation of exchange interaction between the tetrahedral and the octahedral sites.

Structural and Magnetic Properties of BaCo_xFe_12xO₁₉(x = 0.2, 0.4, 0.6, &1.0) Nanoferrites Synthesized via Citrate Sol-Gel Method

Cobalt substituted barium ferrites, BaCoxFe12-xO19 (x = 0.2, 0.4, 0.6 & 1.0) have been synthesized via citrate sol-gel method. All the samples have been annealed at 1000℃ and characterized using Fourier Transform Infra Red spectroscopy, X-Ray Diffractography and Vibrating Sample Magnetometry. The FT-IR spectra of the samples exhibit two frequency bands in the range of 580 cm-1 and 460 cm-1, corresponding to the formation of metal oxides. The XRD studies reveal a crystallite size of ~55 nm. The saturation magnetization decreases from 96.3 emu/g to 47.8 emu/g with increasing concentration of cobalt due to the lower magnetic moment of Co2+ (3 μB) as compared to Fe3+ (5 μB). The coercivity values also show a decreasing behaviour from 3800 Oe to 1750 Oe with increasing cobalt concentration due to reduced magnetocrystalline anisotropy.

Cation Distribution in Lithium Ferrite(LiFe_(5)O_(8))Prepared via Aerosol Route

Nano size lithium ferrite was prepared through aerosol route and characterized using TEM, XRD, magnetic measurements and M?ssbauer spectroscopy. The particle size of as obtained samples were found to be ~10 nm through TEM, that increases upto ~80 nm on annealing at 1200 oC. The unit cell parameter ‘a’ calculated using XRD, confirms the formation of ?-LiFe5O8. Room temperature M?ssbauer spectra of as obtained sample of all the ferrites exhibited broad doublet suggesting super paramagnetic nature. This doublet further resolved into two doublets and assigned to the surface region atoms and internal region atoms of the particles. The annealed samples (1200 oC) show broad sextets, which were fitted with two sextets indicating different local environment of both tetrahedrally and octahedrally coordinated Fe-cation. Cation distribution obtained from the X-ray, magnetic and M?ssbauer data confirms that the three fifth of the iron atom goes in to the octahedral site.

Effect of doping of different rare earth（europium,gadolinium,dysprosium and neodymium） metal ions on structural,optical and photocatalytic properties of LaFeO3 perovskites

Different rare earth substituted perovskites LaRExFe1-xO3(where RE=Eu3+,Gd3+,Dy3+,Nd3+and x=0.02,0.04,0.06,0.08,0.1)with orthorhombic structure and narrow band gaps were successfully fabricated via sol-gel autocombustion method.All the substituted perovskites are found to exhibit excellent photocatalytic activity towards the oxidative degradation of dye molecules.An excellent increase in the rate constant values of pure perovskite(LaFeO3)photocatalytic reactions is observed with the substitution of rare earth metal ions.Best results are obtained for LaNd0.1Fe0.9O3 which exhibits around 7 times increase in the rate constant values for degradation reaction of SO(1.76×10-1 min-1)and RBY(1.69×10-1 min-1)dyes.

Traversing the advantageous role of samarium doped spinel nanoferrites for photocatalytic removal of organic pollutants

The present work reportes the pertinence of samarium(Sm) doped spinel nanoferrites as magnetically recoverable photocatalyst for the removal of organic pollutants from wastewater.Thus,a series of Sm substituted spinel nano ferrites,MSm_(x)Fe_(2-x)O_(4)(M=Ni,Co;x=0,0.02,0.06,0.1) we re synthesized via sol-gel methodology.The effect of Sm doping on the structural,morphological,optical and magnetic properties of pristine nanoferrites was investigated systematically.Further,the fabricated samples were explored as photocatalysts for the oxidative degradation of antibiotics(ofloxacin and norfloxacin) and dyes(methyl orange and safranin O).The Sm doped nanoferrites exhibit astonishing catalytic efficacy that can be attributed to higher surface area,octahedral site preference of Sm ions and reduced band gap.The synthesized nanoferrites display excellent recyclability which enables them to be utilized as potential photocatalysts for wastewater treatment.