| 11. |
- Altincekic, T. G., et al.
(författare)
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Synthesis and characterization of CuFe2O4 nanorods synthesized by polyol route
- 2010
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 493:1-2, s. 493-498
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Tidskriftsartikel (refereegranskat)abstract
- Uniform, high quality, CuFe2O4 nanorods with high aspect ratios were synthesized by a surfactant-free single step polyol process at 220 degrees C. The structure of the product was characterized by XRD and FT-IR, and the morphology of the product was analyzed by SEM. The results showed that the as-prepared nanorods have a uniform cross-section and with average diameter of similar to 100 nm and aspect ratio in the range of 13-52. X-ray line profile fitting resulted in crystallite size of 15 nm, which reveals the polycrystalline nature of these nanorods. Magnetic characterization of product was performed by EPR and VSM techniques and the results show that the CuFe2O4 nanorods are ferromagnetic. The line width of the resonance lines in FMR is about 1.8 kOe which may originate from different resonance fields of randomly distributed nanocrystals which have different orientation of magnetic easy axes.
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| 12. |
- Aydin, M., et al.
(författare)
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Synthesis and characterization of poly(3-thiophene acetic acid)/Fe3O4 nanocomposite
- 2011
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Ingår i: Polyhedron. - : Elsevier BV. - 0277-5387 .- 1873-3719. ; 30:6, s. 1120-1126
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Tidskriftsartikel (refereegranskat)abstract
- Poly(3-thiophene acetic acid)/Fe3O4 nanocomposite is synthesized by the precipitation of Fe3O4 in the presence of poly(3-thiophene acetic acid) (P3TAA). Structural, surface, morphological, thermal properties and conductivity characterization/evaluation of the nanocomposite were performed by XRD, FT-IR, TEM, TGA. and conductivity measurements, respectively. The capping of P3TAA around Fe3O4 nanoparticles was confirmed by FT-IR spectroscopy, the interaction being via bridging oxygens of the carboxylate and the nanoparticle surface through bidentate binding. The crystallite and particle size were obtained as 9 +/- 2 nm and 11 +/- 1 nm from XRD line profile fitting and TEM image analysis, respectively, which reveal nearly single crystalline nature of Fe3O4 nanoparticles. Magnetization measurements reveal that P3TAA coated magnetite particles do not saturate at higher fields. There is no coercivity and remanence revealing superparamagnetic character. Magnetic particle size calculated from the theoretical fitting as 9.1 nm which coincides the values determined from TEM micrographs and XRD line profile fitting. The comparison to the TEM particle size reveals slightly modified magnetically dead nanoparticle surface.
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| 13. |
- Aydin, M., et al.
(författare)
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Synthesis, magnetic and electrical characteristics of poly(2-thiophen-3-yl-malonic acid)/Fe(3)O(4) nanocomposite
- 2012
-
Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 514, s. 45-53
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Tidskriftsartikel (refereegranskat)abstract
- Poly(2-thiophen-3-yl-malonic acid)/Fe(3)O(4) nanocomposite was synthesized by the precipitation of Fe(3)O(4) in the presence of poly(2-thiophen-3-yl-malonic acid) (PT3MA). Characterizations of the nanocomposite were performed by XRD, FT-IR, TEM, TGA, AC/DC conductivity and dielectric measurements. The capping of PT3MA around Fe(3)O(4) nanoparticles was confirmed by FTIR spectroscopy, the interaction being between bridging oxygen of the carboxylate and the nanoparticle surface through bidentate binding. The crystallite particle sizes of 6 +/- 3 nm and 7 +/- 3 nm were obtained from XRD line profile fitting and from TEM image analysis respectively, and they are in good agreement with each other. Magnetization measurements revealed that PT3MA coated magnetite particles do not saturate at higher fields. The material showed superparamagnetic character as revealed by the absence of coercivity and remnant magnetization. Magnetic particle size was calculated as 7.3 +/- 1.0 nm from the mean magnetization term in the Langevin function which is also in conformity with the values determined from TEM micrographs and XRD line profile fitting. The TEM particle size analysis of the nanoparticles revealed the presence of a slightly modified magnetically dead nanoparticle surface. AC and DC conductivity measurements were performed to elucidate the electrical conduction characteristics of the product.
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| 14. |
- Baykal, A., et al.
(författare)
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Acid Functionalized Multiwall Carbon Nanotube/Magnetite (MWCNT)-COOH/Fe3O4 Hybrid : Synthesis, Characterization and Conductivity Evaluation
- 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. 726-735
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Tidskriftsartikel (refereegranskat)abstract
- A functionalized multiwall carbon nanotube (MWCNT)-COOH/Fe3O4 hybrid was fabricated by co-precipitation method. Fe3O4 nanoparticles were stably attached to the surface of carboxyl groups (COOH). The presence of Fe3O4 nanoparticles and their surface conjugation to MWCNT have been confirmed by XRD, TEM and FT-IR techniques. Magnetic evaluation revealed a superparamagnetic character of the hybrid and therefore the attached Fe3O4 nanoparticles. The crystallite size (9 +/- A 3 nm), particle size (9 +/- A 2 nm) and magnetic domain size estimated for Fe3O4 are consistent with each other, which reveal the single crystalline character of the nanoparticles. Electrical conductivity and dielectric behavior have also been characterized by utilizing impedance spectroscopy up to 3 MHz for an isotherm line varying from 293 to 393 K by 10 K steps. Electrical characteristics and its complex dielectric approaches might be elucidated with the existence of a conventional tunneling conduction mechanism of temperature-independency. The AC conductivity of MWCNT-COOH/Fe3O4 hybrid could also be a consequence of the estimations of the universal dynamic response.
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| 15. |
- Baykal, A., et al.
(författare)
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Effect of ionic liquids on the electrical and magnetic performance of polyaniline-nickel ferrite nanocomposite
- 2013
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Ingår i: Materials research bulletin. - : Elsevier BV. - 0025-5408 .- 1873-4227. ; 48:2, s. 378-382
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Tidskriftsartikel (refereegranskat)abstract
- Polyaniline-NiFe2O4 nanofiber composites were successfully synthesized at the interface of water and ionic liquid via in situ polymerization using cetyl trimethylammonium bromide (CTAB) as surfactant. Both TG analysis and FT-IR measurements proved the presence of organic layer on the surface of NiFe2O4 nanoparticles. The influence of 1-butyl-3-methyl-imidazolium bromide [BMIM]Br as ionic liquid on the structure, conductivity and magnetic property of polyaniline-NiFe2O 4-CTAB nanocomposite were studied in detail. The results show that imidazolium-based ionic liquids BMIMBr acts as an anchor agent for the formation of morphology in polyaniline-NiFe2O4-CTAB nanocomposite. Introduction of ionic liquids obviously improves the conductivity but weakens the magnetization of polyaniline-NiFe2O4 nanocomposite.
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| 16. |
- Baykal, A., et al.
(författare)
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Hydrothermal synthesis of SrFe 12O 19 and its characterization
- 2012
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 25:6, s. 2081-2085
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Tidskriftsartikel (refereegranskat)abstract
- We have synthesized strontium hexaferrite particles in an alkaline medium using a hydrothermal process at 180°C. Crystalline phase of samples were determined by XRD and spectroscopic, morphological, and magnetic investigation of the sample were FT-IR, SEM, and TG analysis, respectively. XRD analysis revealed few impurity phases in the as-made powder; upon calcinations, the material is converted to desired hexaferrite phase. As synthesized powder exhibits agglomerates with rather smooth facets, in the form of thick platelets. Upon calcination, all these structures were observed to transfer to rod-like structures. The As calcined sample has high specific saturation magnetization (Ms ) values of 65 emu/g that is close to its theoretical value of 74.3 emu/g but the hydrothermally synthesized sample does not. This is in agreement with the observations from XRD analysis where few impurity phases observed in the as-made powder cause a weak magnetic response. Upon calcination, the material is converted to a desired hexaferrite phase with better magnetic properties.
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| 17. |
- Baykal, A., et al.
(författare)
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Polyol synthesis of (polyvinylpyrrolidone) PVP-Mn3O4 nanocomposite
- 2010
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 502:1, s. 199-205
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Tidskriftsartikel (refereegranskat)abstract
- We report on the synthesis of (polyvinylpyrrolidone) PVP-Mn3O4 nanocomposite via a polyol route. Crystalline phase was identified as Mn3O4 and the crystallite size was obtained as 6 +/- 1 nm from X-ray line profile fitting. Average particle size of 6.1 +/- 0.1 nm obtained from TEM analysis reveals nearly single crystalline nature of these nanoparticles in the composite. The capping of PVP around Mn3O4 nanoparticles was confirmed by FT-IR spectroscopy, the interaction being via bridging oxygens of the carbonyl (C=O) and the nanoparticle surface. T-C and T-B for PVP-Mn3O4 nanocomposite were observed at 42K and 28.5 K, respectively. The sample has hysteresis with small coercivity and remanent magnetization at 40K, resembling the superparamagnetic state. ac conductivity measurements on PVP-Mn3O4 nanocomposite revealed a conductivity in the order of 10(-7) S cm(-1) at lower frequencies. The conductivity change with respect to frequency can be explained by electronic exchange occurring between Mr(+2) and Mn+3 existing in sublattice of spinel lattice.
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| 18. |
- Baykal, A., et al.
(författare)
-
Synthesis and characterization of PEG-Sr hexaferrite by sol-gel conversion
- 2012
-
Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 25:6, s. 2003-2008
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Tidskriftsartikel (refereegranskat)abstract
- Sr-M-type hexagonal ferrites have been prepared via a sol-gel route, and the effects of addition of different molecular weight polyethylene glycol (PEG) into the sol solutions on the static magnetic properties and particle morphology have been studied. Crystalline phases of the samples were determined by XRD analysis. FT-IR and TG analyses were used to prove the presence of PEG on SrFe12O19. The results showed that adding PEG with different molecular weight into the sol solutions affected the formation mechanism of SrFe12O19. Sr-M precursors prepared by various PEG types show different magnetic behaviors after precalcination at 150 degrees C. This discrepancy is explained by the formation of a different phase during the synthesis of SrM particles.
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| 19. |
- Baykal, A., et al.
(författare)
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Triethylene Glycol Stabilized CoFe2O4 Nanoparticles
- 2012
-
Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 25:6, s. 1879-1892
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Tidskriftsartikel (refereegranskat)abstract
- We report on the synthesis and detailed composition, thermal, micro-structural, ac-dc conductivity performance and dielectric permittivity characterization of triethylene glycol (TREG) stabilized CoFe 2O 4 nanoparticles synthesized by polyol method. XRD analysis confirmed the inorganic phase as CoFe 2O 4 with high phase purity. Microstructure analysis with TEM revealed well separated, spherical nanoparticles in the order of 6 nm, which is also confirmed by X-ray line profile fitting. FT-IR analysis confirms that TREG is successfully coated on the surface of nanoparticles. Overall conductivity of nanocomposite is approximately two magnitudes lower than that of TREG with increase in temperature. The ac conductivity showed a temperature dependent behavior at low frequencies and temperature independent behavior at high frequencies which is an indication of ionic conductivity. The dc conductivity of the nanocomposites and pure TREG are found to obey the Ar- rhenius plot with dc activation energies of 0.258 eV and 0.132 eV, respectively. Analysis of dielectric permittivity functions suggests that ionic and polymer segmental motions are strongly coupled in the nanocomposite. TREG stabilized CoFe 2O 4 nanoparticles has lower ε and ε than that of pure TREG due to the doping of cobalt. As the temperature increases, the frequency at which (ε ) reaches a maximum shifted towards higher frequencies. On the other hand, the activation energy of TREG for relaxation process was found to be 0.952 eV which indicates the predominance of electronic conduction due to the chemical nature of TREG. Contrarily, no maximum peak of tan Ύ was observed for the nanocomposite due to the being out of temperature and frequency range applied in the study.
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| 20. |
- Birsoz, B., et al.
(författare)
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Synthesis and characterization of polypyrrole-BaFe12O19 nanocomposite
- 2010
-
Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 493:1-2, s. 481-485
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Tidskriftsartikel (refereegranskat)abstract
- Polypyrrole-BaFe12O19 nanocomposite was successfully synthesized by an in situ polymerization of pyyrole in the presence of synthesized BaFe12O19 nanoparticles. Structural, morphological, electrical and magnetic properties of the nanocomposite were performed by XRD, FT-IR, TEM, TGA, VSM and ac conductivity measurements respectively. XRD analysis reveals the inorganic phase as bariumhexaferrite and TGA shows about 22 wt% loading of hexaferrite in the nanocomposite. FT-IR analysis indicates a successful conjugation of hexaferrite particles with polypyrrole. Magnetization measurements show that polypyrrole coating decreases the saturation magnetization of BaFe12O19 significantly. This reduction has been explained by the pinning of the surface spins by the possible adsorption of non-magnetic ions during the polymerization process. Interactions between the hard and impurity phases, determined using the Stoner-Wohlfarth theory, reveal that particles' single domain character and the coating destabilizes the remanence state of the polypyrrole-BaFe12O19 nanocomposite.
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