Synthesis and Characterization of Cobalt Ferrite Nanoparticles

Cobalt ferrite can be synthesized using several techniques. However, to have wide applications in electronic, medical fields etc., the synthesis technique should be simple and inexpensive. The synthesis technique used to prepare nanoparticles should not consume lot of time and energy. Also it should yield narrow particle size distribution and homogeneity in theprepared material. It was observed that surface modification such as with silica coating on the cobalt ferrite will have significant effect on the structural and magnetic properties. It is also observed that, silica coated nanoparticles could be used in biomedical applications (Hong et al., 2013). In this work we have chosen sol-gel method to synthesize pure cobalt ferrite (CoFe2O4) and silica coated (CoFe2O4 / SiO2) nanoparticles. To observe the effect of silicate coating on the structural and magnetic properties of CoFe2O4 we have carried out the present study. CoFe2O4 nanoparticles were synthesized with SiO2 coating and in pure form by sol-gel method. The obtained particle sizes were 24 and 26 nm in both the cases. The X-ray diffraction patterns showed the formation of CoFe2O4 spinel structure without any traces of SiO2 in the prepared samples. The Infrared spectra showed the bands corresponding to tetrahedral andoctahedral sites as feature of typical spinel ferrites and also band due to SiO2. The particle size and morphology of CoFe2O4 / SiO2 was found to be uniform but in the case of pure CoFe2O4 somewhat agglomerated which is accounted for magnetization of ferrites. The magnetization value for CoFe2O4 / SiO2 showed a drastic decrease when compared to pure CoFe2O4 due to presence of non-magnetic coating layer

Ferromagnetic Behavior in Zinc Ferrite Nanoparticles Synthesized using Coprecipitation Technique

Zinc ferrite have been produced and used by humans since long time, however understanding of ZnFe2O4 as a nano structured materials is very useful in order to be used for technological applications. ZnFe2O4 structural, magnetic and electrical properties are different when synthesized using different techniques. Therefore, it would be interesting to investigate the structural and magnetic properties of ZnFe2O4 when in nanosize. In the present work nanocrystalline ZnFe2O4 was synthesized using coprecipitation technique. The structural and magnetic properties of ZnFe2O4 nanopowders were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), dynamic light scattering (DLS), infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). The XRD of ZnFe2O4 nanoparticles showed the single phase spinel structure. The average particle size of ZnFe2O4 calculated from XRD was observed to be 45 nm. DLS measurements showed the average particle size to be 42 nm. Further, the phase formation of ZnFe2O4 was confirmed from the IR measurements. The IR spectra showed the bands corresponding to ZnFe2O4. We observed the room temperature ferromagnetic behavior in synthesized ZnFe2O4 nanoparticles which may be due to the random distribution of Zn2+ and Fe3+ at the tetrahedral (A) and octahedral [B] sites. In our future work, we want to investigate the defect induced magnetic properties of ZnFe2O4 nanoparticles which is likely to contribute for ferromagnetic behavior in this material

Structural and magnetic Properties of Mn, Co, Ni doped ZnO Nanocrystals

ZnO is one of the most important semiconductor material for research. It is abundant, cost effective, non-toxic and also it is used in many bio-medical applications. The transition metal(TM) such as manganese (Mn), cobalt (Co) and nickel (Ni) doped zinc oxide (ZnO) nanocrystals are promising candidates for variety of practical application due to their spin of electron that lead to new magnetic, optical and transport properties. TM doped ZnO nanocrystals were synthesized using co-precipitation technique. The structural and magnetic properties were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM) measurements. The XRD of Mn-doped ZnO nanocrystals shows hexagonal structure. The crystal size from the XRD was observed to be 10 nm. FTIR spectra shows strong absorption peaks between 200 - 600 cm-1 as a characteristic bands due to the metal ions. The TM doped ZnO nanocrystals shows weak ferromagnetic properties at room temperature. It is well known that, ZnO has large band gap energy about 3.3ev which only absorb light within UV region. TM doped ZnO nanocrystals have very good photo catalytic activities, therefore in our further research work, we plan to investigate different optical properties of these materials