Increasing Cobalt Content Research Articles

Effect of Composition on Thermoelectric Properties of As-Cast Materials: The Cu12−xCoxSb4S13−ySey Case

Samples with Cu12−xCoxSb4S13−ySey (0 ≤ x ≤ 2, 0 ≤ y ≤ 1) nominal compositions were prepared by melting the elements under vacuum, followed by slow cooling. The phases formed in this process were identified and characterized by powder x-ray diffraction and scanning electron microscopy observations, complemented with energy-dispersive spectroscopy. All samples have tetrahedrite as the major phase (> 78 vol.%). However, minority phases like skinnerite and chalcostibite are usually also observed, the number and volume of them increasing with the increase of cobalt content. Measurements of electrical resistivity and Seebeck coefficient showed that these materials can present large power factors, with the Cu11.5Co0.5Sb4S12Se sample having a room temperature value higher than 200 μW K−2 m−1.

Spin-orbit coupling in magnetoelectric Ba3(Zn1-xCox)2Fe24O41 hexaferrites.

The Z-type hexaferrites Ba3(Zn1-xCox)2Fe24O41 (x = 0.2, 0.4, 0.6, 0.8, defined as Z1-Z4) were synthesized by a sol-gel method. With increasing cobalt concentration, the origin of magnetoelectric (ME) coupling and the effects of crystal parameters, occupation of ions, and magnetocrystalline anisotropy (MCA) on ME current were studied systematically. The mechanism of magnetic phase transition, revealing the evolution of the magnetic order in the temperature range of 10-400 K, was discussed in detail. Our results suggest that the ferroelectricity of Z1-Z4 originates from both inverse Dzyaloshinskii Moriya (DM) interaction and p-d hybridization mechanism. In particular the ME coupling property is only dominated by p-d hybridization with spin-orbit coupling. This study provides an effective way to improve the ME coupling property of hexaferrites, which have potential applications in the design of new electronic devices.

Влияние относительного содержания металлической компоненты в диэлектрической матрице на образование и размеры нанокристаллов кобальта в пленочных композитах Co-=SUB=-x-=/SUB=-(MgF-=SUB=-2-=/SUB=-)-=SUB=-100-x-=/SUB=-

AbstractThe influence of relative content of a metal component on the phase composition and substructure of Co_ x (MgF_2)_100 – _ x in a wide range of x = 16–63 at % is studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared (IR) spectroscopy. The layers of nanocomposite with a micron thickness have been obtained by the ion-beam sputtering of the target in the argon environment. The results reveal that the relative metal cobalt content in the MgF_2 dielectric matrix strongly affects the phase composition and substructure of nanocomposites. With a lower content of cobalt, it is in the amorphous state in the form of clusters in the MgF_2 nanocrystalline matrix. An increase of cobalt content to x = 29 at % on a sitall substrate and to x = 42 at % on a glass substrate in the X-ray amorphous MgF_2 dielectric matrix leads to the formation of cobalt nanocrystals with a hexagonal crystallographic system, whose sizes are on the order of 10 nm. These are predominately oriented in the basis plane of the (001) hexagonal lattice of α-Со. A further increase of cobalt content to c = 59 at % enlarges the α-Со nanocrystals to ~20 nm with retaining the same orientation. In accordance with a fine structure analysis of XPS spectra of Со 2 p and О 1 s , cobalt is strongly oxidized on the surface of all the composites; only on the surface of samples with a low content of Co is X‑ray amorphous cobalt found in a metallic state along with cobalt oxide. The IR spectra of these samples with the lowest metal phase content exhibit the pronounced modes from the nanocrystalline MgF_2 dielectric phase.

Effect of synthesis parameters on cobalt ferrite saturation magnetization

Cobalt substituted magnetite, CoxFe1−xFe2O4 was synthesized via co-precipitation method for 0.0≤x≤1.0 and annealed in argon from 600 to 800°C to investigate the effect of synthesis parameters e.g. cation substitution and thermal treatment on its saturation magnetization. Particle size variation, crystallinity and cationic distribution between sublattices which resulted from the varying synthesis parameters are expected to alter the saturation magnetization of cobalt ferrite. Both thermal treatment and cation substitution are affecting the value of saturation magnetization. Correlation of microstructural properties with magnetization were analysed using TG-DTA, XRD, FTIR and VSM. Crystallinity, average crystallite size and lattice constant of the as-annealed samples is increasing with annealing temperature. The presence of maghemite and cobalt oxide as secondary phases have caused reduction in the saturation magnetization. Interestingly, increasing cobalt concentration in the samples has dramatically shifted the temperature at which magnetite transformed to maghemite. We have found that x = 0.4 is the optimum cobalt ratio at which all reactants are converted into reaction product with no incomplete reactions that contribute to the formation of impurities. Preferential occupancy of Co2+ ions on the octahedral sites is evident in the FTIR spectra with intensified octahedral band splitting in the non-stoichiometric CoxFe1−xFe2O4 (0.2≤x≤0.8), whereby the structures formed are in metastable state. It is also evident in the FTIR spectra that distinct absorption bands appeared only when the cations in both sites are well ordered. By substituting Co2+ ions, saturation magnetization keeps on increasing until x=0.4, and gradually reduced beyond that. Highest saturation magnetization (78.86 emu/g) was obtained in Co0.4Fe0.6Fe2O4 after annealing at 800°C. In conclusion, heat treatment and substitution of ferrous/ferric ions with cobalt of lower magnetic moment has amplified the super-exchange interaction between octahedral and tetrahedral sites in magnetite spinel structure for greater saturation magnetization....

Characterization of CBD–CdS nanocrystals doped with Co2+

Co-doped CdS nanofilms are synthesised by chemical bath deposition growth technique at the temperature of 60 ± 2 °C. The cobalt molar fraction was ranged from 0 ≤ x ≤ 5.47, which was determined by energy-dispersive X-ray spectroscopy. The X-ray diffraction shows that the nanofilms are of CoS–CdS nanocomposites with individual CdS and CoS crystalline planes. The Co-doped CdS crystalline phase was zinc-blende that was determined by X-ray diffraction and confirmed by Raman spectroscopy. The average grain size of the CdS films was ranged from 2.56 to 1.67 nm that was determined by Debye–Scherrer equation from ZB (111) direction and it was confirmed by Wang equation and high resolution transmission electron microscopy (HRTEM). Raman scattering shows that the CdS lattice dynamics is characteristic of a bimodal behaviour, in which the first optical longitudinal mode denotes the characteristic peak at 305 cm−1 of the CdS nanocrystals that is associated with the cobalt incorporation. Nanofilms present two main bandgaps at ~ 2.56 and 3.80 eV, which are attributed to single CdS and quantum-confinement due to nanocrystals size. The increase in band gap with increase in cobalt concentration suggests intermetallic compound of CoS (Eg = 1.60 eV) with CdS (Eg = 2.44 eV). The CdS nanocrystals size was ranged from 2.46 to 1.81 nm that was determined from ZB (111) direction by Debye–Scherrer equation and confirmed by the Wang equation. The room-temperature photoluminescence of the Co-doped CdS presents well-resolved radiative bands associated to structural defects and with the quantum-confinement. For the Co-doped CdS the photoluminescence intensity increases indicate a high-passivation of the nanocrystals.

Influence of cobalt substitution on the properties of Ni0.95-xCoxCu0.05Fe2O4 ferrite nanoparticles

Cobalt substituted nickel copper ferrite samples with general formula Ni0.95-xCoxCu0.05Fe2O4, where (x= 0.00, 0.01, 0.02, 0.03, 0.04 and 0.05) were prepared by solid-state reactions method at 1373 K for 4h. The samples prepared were examined by X-ray diffraction (XRD(, atomic force microscope (AFM), Fourier transform infra-red spectroscopy (FTIR) and Vickers hardness. X-ray diffraction patterns confirm the formation of a single phase of cubic spinel structure in all the prepared samples . XRD analysis showed that the increase in the cobalt concentration causes an increase in the lattice constant, bulk density (ρm) and the x-ray density (ρx), whereas porosity (p) and crystallite size (D) decrease. The Topography of the surface observed was found to be more uniform and homogeneous when the cobalt concentration increases, leading to a decrease in the roughness of the surface while average grains size increases. The FTIR spectra show two absorption bands, namely the high frequency band (υ1) in the range (1078-1081) cm-1 and the low frequency band (υ2) in the range (418–459) cm-1, which due to the vibrations of the tetrahedral and octahedral sites of Fe+3–O−2, respectively, these bands confirm the spinel structure of the prepared ferrite nanoparticles. Vickers hardness was found to increase with cobalt concentration increases.

Influence of Cobalt Ions on Collagen Gel Formation and Their Interaction with Osteoblasts

Metals on metal implants have long been used in arthroplasties because of their robustness and low dislocation rate. Several relatively low-corrosion metals have been used in arthroplasty, including 316L stainless steel, titanium, and cobalt–chromium–molybdenum alloy. Debris from these implants, however, has been found to cause inflammatory responses leading to unexpected failure rates approaching 10% 7 years surgery. Safety assessment of these materials traditionally relies on the use of simple two-dimensional assays, where cells are grown on the surface of the material over a relatively short time frame. It is now well-known that the composition and stiffness of the extracellular matrix (ECM) have a critical effect on cell function. In this work, we have evaluated how cobalt ions influence the assembly of type I collagen, the principle component of the ECM in bone. We found that cobalt had a significant effect on collagen matrix formation, and its presence results in local variations in collagen density. This increase in heterogeneity causes an increase in localized mechanical properties but a decrease in the bulk stiffness of the material. Moreover, when collagen matrices contained cobalt ions, there was a significant change in how the cells interacted with the collagen matrix. Fluorescence images and biological assays showed a decrease in cell proliferation and viability with an increase in cobalt concentration. We present evidence that the cobalt ion complex interacts with the hydroxyl group present in the carboxylic terminal of the collagen fibril, preventing crucial stabilizing bonds within collagen formation. This demonstrates that the currently accepted toxicity assays are poor predictors of the longer-term biological performance of a material.

Barrier ability and durability of Ni[sbnd]Co[sbnd]P coatings in accordance to the content of H3PO3 and NaH2PO2 as phosphorus sources

The effect of P-providing components (phosphorous acid, H3PO3 and sodium hypophosphite, NaH2PO2) in modified Watts electrolyte (pH = 2; 80 °C) on the barrier ability and durability of the deposited NiCoP and NiCo (as a reference) coatings during extended exposure in 3.5% NaCl until 672 h was studied. The data acquired for the charge transfer and polarization resistances (Rct and Rp) by electrochemical impedance spectroscopy, EIS and linear voltammetry, LVA, undoubtedly reveal that the best corrosion protective properties belong to the NiCoP coating deposited at simultaneous occurrence of H3PO3 and NaH2PO2. It was followed subsequently by those obtained from electrolyte with only NaH2PO2, then, deposited from electrolyte with only H3PO3 and finally by the reference NiCo coating. The occurrence of an amorphous phase in the structure of NiCoP coatings, combined with the increase of cobalt content and reducing that of nickel, predetermines the best protective properties of the investigated alloys. The established anomalous Rct and Rp increment during the exposure of NiCoP coatings could be related to corrosion products accumulation, most probably of metal phosphates, and it forms a barrier layer between the coating and the corrosive medium.

Liquid phase oxidation of cyclohexane over mesoporous cobalt silicates molecular sieves synthesized in strong acidic media by assembly of preformed CoS-1 precursors with triblock copolymer

Cobalt–incorporated mesoporous silica materials [MCoS(n), n = Si/Co = 20; 60] have been successfully prepared in strong acidic media by assembly of preformed CoS-1 precursors with triblock copolymer of the Pluronic type (P123) by a two steps procedure. They were characterized by various techniques including XRD, BET, FT-IR spectroscopy and diffuse reflectance UV–Vis (DRUV–Vis). The results show that the calcined MCoS materials contain Co(II) ions in tetrahedral environments under low and high Co content and the mesoporous walls contain the MFI structure building units. Liquid phase oxidation of cyclohexane using TBHP as oxidant was investigated on MCoS(n). The major products detected are cyclohexanone and cyclohexanol in all cases. The MCoS(n) catalysts are more active when water free TBHP was used and the conversion of cyclohexane increases when cyclohexane to TBHP molar ratio increases from 1:1 to 1:2, while the cyclohexanol selectivity decreases, which is ascribed to a further oxidation of cyclohexanol to cyclohexanone. The catalytic activity of MCoS(n) materials is enhanced as the cobalt content increases. It is worth noting that MCoS(20)is more active than Co-SBA15(20). The most active catalyst MCoS(20) acts as truly heterogeneous catalyst and was very stable after four runs.

Co4N/nitrogen-doped graphene: A non-noble metal oxygen reduction electrocatalyst for alkaline fuel cells

Cobalt-nitride (Co4N) nanoparticle-decorated nitrogen-doped graphene sheets were obtained via the nitrogen doping of a graphene-oxide precursor and simultaneous nitride formation. The non-precious metal catalyst formed in this one-step synthesis exhibits high electrocatalytic oxygen reduction activity and hence provides a promising alternative to conventional Pt/C alkaline fuel cell cathode catalysts. The reported composites were formed from the mixture of lyophilized graphene-oxide nanosheets and cobalt(II) acetate in ammonia atmosphere at 600 °C. The average Co4N particle size increased from 14 to 201 nm with the increase in cobalt content. The oxygen reduction activity of the new catalysts was comparable to that of non-noble metal systems described in the literature, and also to the widely-used carbon black supported platinum catalysts. The highest reduction current density under alkaline conditions was found to be as high as 4.1 mA cm−2 with the corresponding electron transfer number of 3.6. Moreover, the new system outperformed platinum-based composites in terms of methanol tolerance, thus eliminating one of the major drawbacks (besides high price and limited availability), of noble metal catalysts.

Increase of surface hardness and substrate toughness due to migration of grain growth inhibitors in the ultrafine-grained layer during sintering of functionally graded cemented carbides

Annotation This work is devoted to increasing the hardness of the surface and toughness of the substrate of the functionally graded hard alloy obtained from sintering the medium-grained (WC-15Co) and ultrafine-grained (WC-8Co-0.4VC-0.4Cr3C2) layers. The migration of the liquid phase from the medium-grained layer to the ultrafine-grained layer during sintering leads to the displacement of grain growth inhibitors (VC + Cr3C2) dissolved in cobalt to the surface of the ultrafine-grained layer. Local slowing of grain growth increases the hardness of the surface of the ultrafine-grained layer up to 1680 HV. An increase in the local concentration of cobalt near the interface in the medium-grained layer increases the toughness to 18.9 MPa√m. Studies on cobalt and grain growth inhibitors concentrations, average grain diameters, contiguity, hardness and toughness over the depth of samples sintered at 1350 °C, 1370 °C, 1390 °C, and 1410 °C were carried out. The obtained results were compared with theoretical estimates based on the Gurland equations.

Enhancement in power conversion efficiency of silicon solar cells with cobalt doped ZnO nanoparticle thin film layers

In this study, we report results on coating silicon solar cells with undoped and cobalt-doped zinc oxide (5%, 10%, 15%, and 20%) nanoparticles ranging in diameter from 46 nm to 87 nm, synthesized by a simple low-temperature precipitation method. The morphology and structure of nanoparticles have been characterized by transmission electron microscopy and X-ray diffraction spectroscopy. The average size of nanoparticles was found to increases with the increase in cobalt concentration. Doped and undoped zinc oxide thin films were deposited by a simple spin coating technique on silicon solar cells. Optical properties of the cobalt-doped zinc oxide layer have been investigated. We estimated the thin film stress by adding nanoparticles layers and found that the stress is lowest for the 139 nm cobalt-doped zinc oxide layer. Bandgap was found to increase with an increase in zinc oxide nanoparticle thin film thickness. Photoluminescence spectra show a blue shift in the near band edge emission peak with increase in thickness. Current-Voltage measurement confirms that there is an enhancement in power conversion efficiency as the thickness of zinc oxide nanoparticles varied from 58 nm to 139 nm. In general, the conversion efficiency shows an increasing trend up to 139 nm of thickness in silicon solar cells coated with doped and undoped zinc oxide nanoparticles. In addition, there is an enhancement of external quantum efficiency with an increase in thickness of zinc oxide layer. The optimal thickness of nanostructured zinc oxide film layer to enhance the efficiency of the silicon photovoltaic cell was experimentally determined to be 139 nm.

Effect of Co doping on CIS2 thin films

In recent years, substantial scientific attention has been focused on renewable energy resources, which utilize natural resources for the production of electrical energy. Chalcopyrite semiconductors are used as one of the alternatives, Cu(In,Ga)Se2 (CIGS) and CuInS2 (CIS) are used for the fabrication of solar cells. These materials possess various properties Viz. ideal band gap (1.5 eV), high optical absorption, low light degradation, high radiation resistance, etc., hence they are suitable in the fabrication of solar cells. In contrast to other chalcopyrates, CuInS2 is nontoxic, low-cost and easy to prepare by simple deposition techniques. Several impurities were doped to CuInS2 bulks, to control conduction and also to obtain low resistivity. In this context, the structural, morphological and optical properties are reported for cobalt-doped CuInS2 (CIS2) thin films prepared by electro-deposition technique at room temperature. In the present study, we have used different cobalt concentration in the range of 0–5 wt.%. Doping of cobalt does not lead to the formation of any secondary phase, either in the form of metallic clusters or impurity complexes. However, with increase in cobalt concentration a decrease in the optical band gap, from 2.10 to 1.53 eV, is observed. In addition, implantation of cobalt in the CIS2 gave changes in structural and surface properties of the thin films obtained. These thin films are also subjected to elemental analysis using EDAX.

Effects of Co Substitution on the Microstructural, Infrared, and Electrical Properties of Mg0.6 − xCoxZn0.4Fe2O4 Ferrites

Spinel ferrites having Mg0.6 − xCoxZn0.4Fe2O4 (0 ≤ x ≤ 0.6) compositions were prepared using the sol–gel method. XRD patterns show that samples have the cubic phase of the spinel ferrite with the $Fd\bar {3}m$ space group. The obtained values of the lattice constant and porosity increase with increasing cobalt concentration. FTIR spectra show only the tetrahedral stretching peaks that are shifting towards higher frequencies with increasing Co content. The substitution of Mg by Co leads to the decrease of conductivity of the samples. The behaviors of the real part of permittivity and loss tangent have been investigated using Maxwell theory. Electrical modulus and impedance results show the presence of the electrical relaxation phenomenon for the samples with non-Debye type. The Nyquist representations have been analyzed using a proposed electrical circuit, and the results show that the resistances of the prepared samples resulted mostly from the grain boundary effect.

The influence of Co content on the luminescence properties of Co-doped ZnO nanoparticles

Co-doped ZnO nanoparticles have been synthesized by co-precipitation technique. Photoluminescence spectra change in the range from 350 nm to 600 nm and remain unchanged at about 690 nm with the Co content increase. The UV emission is assigned to exciton emission. The density of band-edge states increases with Co content. The blue emission could be ascribed to the recombination of electrons in Co[Formula: see text] ions and holes in the valence band, whose relative intensity and full-width at half-maximum (FWHM) increase with the increase of cobalt concentration. The red emission results from the intra-d-shell emission at Co, which is independent of Co content. The relative density and energy-level position of green emission centers are also influenced by Co content.

Enhanced Magnetic Permeability in Ni0.55−yCoyZn0.35Mg0.10Fe2O4 Synthesized by Sol-Gel Method

Growth in permeability with increasing cobalt content in Ni-Zn ferrite is a rare phenomenon. The rise in magnetic anisotropy associated with the cobalt, in general, suppresses the relative permeability of the material. However, cobalt substituted nickel-zinc ferrite of composition, Ni0.55−yCoyZn0.35Mg0.10Fe2O4 (y= 0.00, 0.04, 0.08, 0.12, 0.16, 0.20), synthesized by sol-gel method, showed an enhanced relative initial permeability from 100 to 220 in the frequency range 60 Hz to 50 MHz with increasing cobalt content. The factors causing the permeability increase have been discussed in terms of the observed variations in particle size, saturation magnetization, and Curie temperature. The magnetization process under the influence of cobalt has been illustrated in detail with the help of dM/dH versus magnetization curves.

Influence of Oxygen Vacancies on the Magnetic Properties of Zn1 – xCo x O y Films

Thin films of Zn1 – xCo x O y (х = 0–0.3) with a temperature of the ferromagnetic transition of ТС > 300 K are obtained from ZnO–Co3O4 ceramic targets. The electron concentration in the films is found to decrease exponentially with increasing cobalt content. It is revealed that the magnetization of the films obtained under oxygen deficiency conditions varies in a nonmonotonous way as the cobalt concentration increases. This is caused by the oxidation of metallic nanoclusters of cobalt due to an increase in the oxygen content in the targets. Investigation of the transmission spectra of Zn1 – xCo x O y films revealed extrema in the visible region of the spectrum and near the edge of the fundamental absorption band, associated with electron states introduced by cobalt.

Inter-layer free cobalt-doped silica membranes for pervaporation of ammonia solutions

This study demonstrated the application of a new type of interlayer-free cobalt-doped silica membrane in treating ammonia solutions by pervaporation applied towards wastewater treatment. For enhanced hydrothermal stability, cobalt-doped silica (CoSi) membranes with increasing cobalt concentrations from 1 to 35 mol% were prepared and evaluated, namely CoSi-1, 5, 20 and 35. These membranes exhibited high water fluxes of 66 L m−2 h−1 for CoSi-1 and 15.5 L m−2 h−1 for CoSi-35 at 45 °C. The fluxes of the membranes decreased with increasing cobalt concentration; while the rejection to total nitrogen (TN, ammonia nitrogen) increased and hence allowed selective passage of water molecules. Enhanced thermostability was observed for the membranes, particularly CoSi-35 that exhibited TN rejection up to 99% at high temperature of 65 °C and highly alkaline environment (pH > 10). Also, the CoSi-35 membrane showed stable performance in treating ammonia present in industry wastewater by achieving stable TN and mineral rejections of 97% and 99%, respectively. Fouling was observed and confirmed by SEM morphological analysis and EDX elemental inspection. The results indicated the deposition of low solubility salts such as CaSO4.

OXYGEN SOLUBILITY IN CARBON-CONTAINING Fe –Co MELTS

Thermodynamic analysis of oxygen solutions in carbon-containing Fe – Co melts has been carried out. The equilibrium constants of interaction of carbon and oxygen, the activity coefficients at infinite dilution, and the interaction parameters for melts of different composition at 1873 K were determined. The dependences of the oxygen solubility on the contents of cobalt and carbon in the studied melts were calculated. Carbon has a high affinity for oxygen in iron-cobalt melts. Deoxidation ability of carbon increases significantly with the increasing of cobalt content in the melt. Deoxidation ability of carbon in pure cobalt more than an order of magnitude higher than that in pure iron. Reaction products of carbon deoxidation are gaseous oxides – monoxide (CO) and carbon dioxide (CO 2 ). The interaction reaction of carbon and oxygen dissolved in the melt, and hence deoxidation ability of carbon depends on the total pressure of the gaseous phase above the melt. Deoxidation ability of carbon increases significantly with the gaseous phase pressure lowering. The minimum oxygen concentration achieved for alloys of the same composition decreased practically an order of magnitude at decrease 10 times the total pressure of the gaseous phase. The gaseous phase composition above Fe – Co melts and equilibrium carbon and oxygen concentrations in the melt at a total pressure of the gaseous phase P, of 1.0; 0.1 and 0.01 atm were calculated. Optimum oxygen concentration (1 – 10 ppm) in Fe – Co melts, depending on the total pressure of the gaseous phase (0.01 – 1 atm) is achieved at carbon contents from 0.01 to 1 %. The curves of the oxygen solubility in carbon-containing iron-cobalt melts pass through a minimum, which shifts toward lower carbon contents with increasing cobalt content in the melt. Further carbon additions leads to an increase in the oxygen concentration of the melt so that the higher cobalt content of the melt, the steeper the increase in the oxygen content after the minimum as carbon is added to the melt.

Antibacterial applications of \u03b1-Fe2O3/Co3O4 nanocomposites and study of their structural, optical, magnetic and cytotoxic characteristics

Owing to their multiple mechanisms of bactericidal activity, inorganic metal oxides and hybrid metal oxide nanocomposites may serve as a new class of effective disinfectants. Among metal oxide nanoparticles, iron oxide nanoparticles exhibit minimal or no cytotoxicity to human cells with very efficient bactericidal properties over a wide spectrum of bacteria. This paper presents the very first report on antibacterial properties of novel nanocomposites of iron oxide and cobalt oxide nanoparticles against pathogenic bacterial strains B. subtilis, S. aureus, E.coli and S. typhi. The enhanced bactericidal activity of the Fe/Co oxide nanocomposite was the result of synergistic effect of iron oxide and cobalt oxide nanoparticles. The nanocomposites were synthesized using co-precipitation route with increasing cobalt content in the sample and further characterized using XRD, TEM, Raman and VSM to investigate structural, optical and magnetic properties of the prepared nanocomposites, respectively. Also, the prepared nanocomposites were highly biocompatible and found non-toxic to human cell line MCF7.