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    Effect of bimetallic (Ni and Co) substitution on magnetic properties of MnFe2O4 nanoparticles
    (Elsevier Ltd, 2016) Topkaya, Ramazan; Güngüneş, Hakan; Eryiğit, Ş. Ş.; Shirsath, Sagar E.; Yıldız, Aylin; Baykal, Abdulhadi
    Nickel and cobalt substituted manganese ferrite nanoparticles (NPs) with the chemical composition NixCoxMn1–2xFe2O4 (0.0?x?0.5) NPs were synthesized by one-pot microwave combustion route. The effect of co-substitution (Ni, Co) on structural, morphological and magnetic properties of MnFe2O4 NPs was investigated using XRD, FT-IR, SEM, VSM and Mössbauer spectroscopic techniques. The cation distribution of all products were also calculated. Both XRD and FT-IR analyses confirmed the synthesis of single phase spinel cubic product for all the substitutions. Lattice constant decreases with the increase in concentration of both Co and Ni in the products. From 57Fe Mössbauer spectroscopy data, the variations in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values with Mn2+, Ni2+ and Co2+ substitution have been determined. While the Mössbauer spectra collected at room temperature for the all samples are composed of magnetic sextets, the superparamagnetic doublet is also formed for MnFe2O4 and Ni0.2Co0.2Mn0.6Fe2O4 NPs. The magnetization and Mössbauer measurements verify that MnFe2O4 and Ni0.2Co0.2Mn0.6Fe2O4 NPs have superparamagnetic character. The saturation and remanence magnetizations, magnetic moment and coercive field were determined for all the samples. Room temperature VSM measurements reveals saturation magnetization value close to the bulk one. It has been observed that the saturation magnetization and coercive field increase with respect to the Ni and Co concentrations. © 2016 Elsevier Ltd and Techna Group S.r.l.
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    Magnetic properties and hyperfine interactions of Co1-2xNixMnxFe2O4 nanoparticles
    (Elsevier Ltd, 2017) Baykal, Abdulhadi; Eryiğit, Ş. Ş.; Topkaya, Ramazan; Güngüneş, Hakan; Amir, Md.; Yıldız, Aylin; Kurtan, Ümran; Shirsath, Sagar E.
    Co1-2xNixMnxFe2O4 (0.0?x?0.5) nanoparticles (NPs) were prepared via citrate assisted microwave combus-tion route. XRD analysis confirmed the cubic structure (spinel) of all samples. Average crystallite size ofproducts (obtained from (311) diffraction line) was in the range of 32.9–43.4 nm. The intense peak appearing ataround 531 cm?1in FT-IR was attributed to the formation of a spinel ferrite. Magnetic properties of theproducts were investigated by room temperature vibrating sample magnetometer and Mössbauer spectroscopy.The magnetic parameters have been found to strongly depend on the Ni and Mn concentrations. The saturationmagnetization continuously decreases with the increasing of the concentration (x). We found thatNi0.5Mn0.5Fe2O4NP has superparamagnetic character at room temperature. This result was also verified byMössbauer analysis. Scanning electron microscopic analysis revealed the cubic morphology of all products, EDXand elemental mapping analyses confirmed the expected composition of each product.