| 1. |
- Kurtan, U., et al.
(författare)
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Influence of calcination rate on morphologies and magnetic properties of MnFe2O4 nanofibers
- 2016
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 42:16, s. 18189-18195
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, we succesfully synthesized electrospun MnFe2O4 nanofibers (NFs) from poly(N-vinylpyrrolidone)/manganese(II) nitrate composite by electrospinning and then as-spun NFs were calcined 450 degrees C for 2 h in air atmosphere to remove the polymer matrix and fabricate inorganic MnFe2O4 nanofibers. In order to investigate the sintering behavior of MnFe2O4 nanofibers in air atmosphere, the synthesized as-spun nanofibers were calcined with different calcination rates. Thus the effect of calcination rate on structure and morphology of nanofibers were discussed clearly. The structural, magnetic, morphological, spectroscopic and thermal characterizations were also done by XRD, VSM, TEM, SEM, FTIR and TG analysis. In the presence of slow calcination rate, only peaks of MnFe2O4 could be observed on other hand in the presence of rapid calcination rate, formation of an impurity was observed. Scanning electron microscope images revealed that MnFe2O4 nanorods possess a broader range size distribution with higher particle size. Also, magnetic properties were both size and shape dependent.
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| 2. |
- Kurtan, U., et al.
(författare)
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Magnetically Recyclable Fe3O4@His@Cu Nanocatalyst for Degradation of Azo Dyes
- 2016
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Ingår i: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 16:3, s. 2548-2556
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Tidskriftsartikel (refereegranskat)abstract
- Fe3O4@His@Cu magnetic recyclable nanocatalyst (MRCs) was synthesized by reflux method using L-histidine as linker. The composition, structure and magnetic property of the product were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Fourier Transform infrared spectroscopy (FT-IR) and vibrating sample magnetometry (VSM). Powder XRD, FTIR and EDAX results confirmed that the as-synthesized products has Fe3O4 with spinel structure and Cu nanoparticles with moderate crystallinity without any other impurities. The surface of the Fe3O4@His nanocomposite was covered by tiny Cu nanoparticles. We examine the catalytic activity of Fe3O4@His@Cu MRCs for the degradation of two azo dyes, methyl orange (MO) and methylene blue (MB) as well as their mixture. The reusability of the nanocatalyst was good and sustained even after 3 cycles. Therefore this innovated Fe3O4@His@Cu MRCs has a potential to be used for purification of waste water.
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| 3. |
- Kurtan, U., et al.
(författare)
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Temperature dependent magnetic properties of CoFe2O4/CTAB nanocomposite synthesized by sol gel auto-combustion technique
- 2013
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 39:6, s. 6551-6558
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Tidskriftsartikel (refereegranskat)abstract
- A CoFe2O4/cetyl trimethylammonium bromide (CTAB) nanocomposite has been fabricated by a sol gel auto-combustion method. Characterization of the material revealed the composition of the crystalline phase as CoFe2O4 while FT-IR confirmed the presence of CTAB on the nanoparticles. From X-ray line profile fitting, average crystallite size was estimated to be 22 +/- 6 nm. SEM analysis showed a porous sheet-like morphology with internal nanosize grains of about 30 nm. The room temperature coercive field (He) of the CoFe2O4/CTAB nanocomposite was found to be 1045 Oe which is close to the previously reported room temperature values for bulk CoFe2O4. The H-c, was observed to decrease almost linearly with the square root of the temperature (root T) according to Kneller's law. From the linear fit of H-c versus root T, the zero-temperature coercivity (H-c0) and superparamagnetic blocking temperature (T-B) of the CoFe2O4/CTAB nanocomposite were found to be similar to 9.1 kOe and similar to 425 K, respectively. The remanence magnetization (M-r), the reduced remanent magnetization (M-r/M-s), and the effective magnetic anisotropy (K-eff) decrease with increasing temperature. The M-r/M-s value of 0.6 at 10 K higher than the theoretical value of 0.5 for non-interacting single domain particles with the easy axis randomly oriented suggests the CoFe2O4/CTAB nanocomposite to have cubic magnetocrystalline anisotropy according to the Stoner Wohlfarth model.
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| 4. |
- Sozeri, H., et al.
(författare)
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Polyaniline (PANI)-Co0.5Mn0.5Fe2O4 nanocomposite : Synthesis, characterization and magnetic properties evaluation
- 2013
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 39:5, s. 5137-5143
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Tidskriftsartikel (refereegranskat)abstract
- Polyaniline (PANI)/Cobalt-manganese ferrite, (PANI)/Co0.5Mn0.5Fe2O4, nanocomposite was synthesized by oxidative chemical polymerization of aniline in the presence of ammonium peroxydisulfate (APS). Microwave assisted synthesis method was used for the fabrication of core CoFe2O4 nanoparticles. The structural, morphological, thermal and magnetic properties of the nanocomposite were investigated in detail by X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The average crystallite size of (PANI)/Co0.5Mn0.5Fe2O4 nanocomposite by the line profile method was 20 +/- 9 nm. The magnetization measurements revealed that (PANI)/Co0.5Mn0.5Fe2O4 nanocomposite has superparamagnetic behavior with blocking temperature higher than 300 K. The saturation magnetization of the composite is considerably low compared to that of CoFe2O4 nanoparticles due to the partial replacement of Co2+ ions and surface spin disorder. As temperature decreases, both coercivity and strength of antiferromagnetic interactions increase which results in unsaturated magnetization of the nanocomposite.
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| 5. |
- Topkaya, R., et al.
(författare)
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Polymer Assisted Co-precipitation Synthesis and Characterization of Polyethylene Glycol (PEG)/CoFe2O4 Nanocomposite
- 2013
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Ingår i: Journal of Inorganic and Organometallic Polymers and Materials. - : Springer Science and Business Media LLC. - 1574-1443 .- 1574-1451. ; 23:3, s. 592-598
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Tidskriftsartikel (refereegranskat)abstract
- Polyetylene glycol (PEG)/CoFe2O4 nanocomposite have been synthesized by PEG assisted co-precipitation method. The presence of PEG on the surface of CoFe2O4 nanoparticles was confirmed by Fourier transform infrared spectroscopy. Vibrating sample magnetometer measurements revealed a saturation magnetisation (M (s)) value of 90.95 emu/g, which is higher than bulk value, and coercive field (H (c)) of 862 Oe that is close to the bulk value at room temperature. The temperature dependent magnetization increases initially and then decreases with increasing temperature. This anomality is attributed to the decrease of B sublattice magnetization more rapidly than A sublattice magnetization. The M (r)/M (s) values lower than theoretical value of 0.5 suggests that the PEG/CoFe2O4 nanocomposite has effective uniaxial anisotropy according to the Stoner-Wohlfarth model. Enhanced magnetic properties (higher M (s) and bulk-like H (c) value) make the PEG/CoFe2O4 nanocomposite a promising candidate for high density magnetic recording media.
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| 6. |
- Topkaya, R., et al.
(författare)
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Polyvinylpyrrolidone (PVP)/MnFe2O4 nanocomposite : Sol-Gel autocombustion synthesis and its magnetic characterization
- 2013
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 39:5, s. 5651-5658
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Tidskriftsartikel (refereegranskat)abstract
- A polyvinylpyrrolidone (PVP)/MnFe2O4 nanocomposite was prepared by the sol-gel autocombustion method and its structural, thermal, spectroscoppic, morphological and magnetic characterizations were done by XRD, FT-IR, TGA, SEM and VSM techniques. The presence of MnFe2O4 was confirmed by XRD and the size of crystallites was estimated to be 11 +/- 3 nm. Morphology analysis by SEM revealed spherical agglomerates of 15 nm. The magnetization curves confirm a superparamagnetic behavior with a blocking temperature of 287 K. The M-r/M-s value suggests the presence of uniaxial anisotropy in MnFe2O4 nanoparticles, instead of the expected cubic anisotropy according to the Stoner-Wohlfarth model. The effective magnetic anisotropy constant K-eff has been determined to be about 1.42 x 10(6) erg/cm(3) which is significantly higher than that of the bulk MnFe2O4. This suggests a strong magnetic coupling between magnetically ordered core spins and disordered surface spins of the nanoparticles in the nanocomposite.
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