SwePub - search: WFRF:(Durmus Z.)

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1.	Aydin, M., et al. (author) Synthesis and characterization of poly(3-thiophene acetic acid)/Fe3O4 nanocomposite 2011 In: Polyhedron. - : Elsevier BV. - 0277-5387 .- 1873-3719. ; 30:6, s. 1120-1126 Journal article (peer-reviewed)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.
2.	Baykal, A., et al. (author) Hydrothermal synthesis of SrFe 12O 19 and its characterization 2012 In: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 25:6, s. 2081-2085 Journal article (peer-reviewed)abstract We have synthesized strontium hexaferrite particles in an alkaline medium using a hydrothermal process at 180Â°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.
3.	Baykal, A., et al. (author) Polyol synthesis of (polyvinylpyrrolidone) PVP-Mn3O4 nanocomposite 2010 In: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 502:1, s. 199-205 Journal article (peer-reviewed)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.
4.	Baykal, A., et al. (author) Synthesis and Characterization of Dendrimer-Encapsulated Iron and Iron-Oxide Nanoparticles 2012 In: JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 25:5, s. 1541-1549 Journal article (peer-reviewed)abstract In this paper, a series of iron (Fe) containing nanoparticles were prepared by employing PAMAM (Poly(amidoamine), dendrimers with different generations (G0-G3) as templates and sodium borohydride as a reducing agent. The products have been characterized by TEM, FT-IR, XRD, VSM, TGA, and XPS. XRD analysis reveal low crystallinity of formed particles within the dendrimers, however, crystallinity of the nanoparticles was observed to increase with increasing generation of dendrimers. Dominant phases were determined as magnetite (Fe3O4 or maghemite, gamma-Fe2O3). XPS analysis revealed the chemical composition of nanoparticles as iron oxide which indicated the oxidation of Fe species subsequent to the reduction process, in agreement with XRD analysis. The magnetization curves have superparamagnetic nonhysteretic characteristic at lower fields and with nonsaturation characteristic at high fields. Magnetic evaluation of samples with the 20:1 molar ratio of Fe:PAMAM showed decreasing superparamagnetic character and decreasing saturation magnetisation with increasing generation of dendrimers.
5.	Baykal, A., et al. (author) Synthesis and characterization of PEG-Sr hexaferrite by sol-gel conversion 2012 In: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 25:6, s. 2003-2008 Journal article (peer-reviewed)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.
6.	Baykal, A., et al. (author) Triethylene Glycol Stabilized CoFe2O4 Nanoparticles 2012 In: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 25:6, s. 1879-1892 Journal article (peer-reviewed)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 Îµ and Îµ than that of pure TREG due to the doping of cobalt. As the temperature increases, the frequency at which (Îµ ) 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 ÎŽ was observed for the nanocomposite due to the being out of temperature and frequency range applied in the study.
7.	Bughrara, K.S.M., et al. (author) Effect of intervention strategies on seasonal thermal comfort conditions in a historic mosque in the Mediterranean climate 2018 In: Conference Report. - : Uppsala University. - 9789151908380 ; , s. 363-371 Conference paper (peer-reviewed)
8.	Deligoz, H., et al. (author) Synthesis, structural and electrical properties of triethylene glycol (TREG) stabilized Mn0.2Co0.8Fe2O4 NPs 2012 In: Materials research bulletin. - : Elsevier BV. - 0025-5408 .- 1873-4227. ; 47:3, s. 537-543 Journal article (peer-reviewed)abstract Triethylene glycol (TREG) stabilized Mn0.2Co0.8Fe2O4 NPs was synthesized by a glycothermal reaction. XRD analysis identified the product as Mn0.2Co0.8Fe2O4 with a high phase purity. Nano-sized particles with an average size of about 6-8 nm were obtained with nearly single crystalline nature with TEM analysis. Superparamagnetic-like behavior of TREG stabilized Mn0.2Co0.8Fe2O4 NPs was observed by VSM. The binding between TREG and Mn0.2Co0.8Fe2O4 NPs was investigated with FT-IR and found to be via O on the TREG and NP surface. TG analysis indicated that the Mn0.2Co0.8Fe2O4 NP content was about 40%, with a TREG-shell content to be around 60%. Overall conductivity of the nanocomposite is in the range of 10(-10) to 10(-7) S cm(-1) with a strong dependence on temperature and frequency, indicating ionic conductivity. The nanocomposite exhibited lower epsilon' and epsilon '' compared to TREG stabilized Mn0.2Co0.8Fe2O4 NPs due to the doping of co-doping of manganese and cobalt.
9.	Deligöz, H., et al. (author) Synthesis, structural, magnetic and electrical properties of Co 1-xZnxFe2O4 (x = 0.0, 0.2) nanoparticles 2013 In: Materials research bulletin. - : Elsevier BV. - 0025-5408 .- 1873-4227. ; 48:2, s. 646-654 Journal article (peer-reviewed)abstract Co1-xZnxFe2O4 spinel nanoparticles with Zn concentrations of x = 0.0, 0.2 were prepared by a hydrothermal route in the presence of triethylene glycol (TEG). The structural, magnetic, electrical and dielectric properties of the prepared nanoparticles were studied. The XRD results confirmed the formation of single spinel ferrite structure with crystallite size 9 and 10 nm for x = 0.0 and 0.2 compositions respectively. The lattice parameter (a) increased with increasing Zn concentration. Temperature and frequency dependent electrical and dielectric properties of the prepared ferrites have also been investigated. Our findings show that overall conductivity of Co0.8Zn0.2Fe 2O4 nanoparticle is lower than that of CoFe 2O4 and roughly in the range of 10-11-10 -7 S cm-1 depending strongly temperature and frequency owing to the formation of stable electric bonds between the Zn2+ and Fe2+ ions, which localizes Fe2+ charge carriers. 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. dc conductivity of Co0.8Zn0.2Fe 2O4 nanoparticle are found to obey the Arrhenius plot and can be classified into two regions over with activation energy of 0.113 and 0.163 eV in the ranges of 20-40 °C and 70-120 °C, respectively when CoFe2O4 has an activation energy of 0.245 eV.
10.	Durmus, Z., et al. (author) Effect of Fuel on the Synthesis and Properties of Poly(methyl methacrylate) Modified SrFe12O19 Nanoparticles 2012 In: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 25:6, s. 1957-1963 Journal article (peer-reviewed)abstract Nanosized strontium hexaferrite (SrFe 12O 19) has been synthesized by citrate, urea, oxalic, and glycine precursor via a sol-gel route with poly(methyl methacrylate) (PMMA) as a templating agent. Crystal structure, morphology, and magnetic properties of as-synthesized nanoparticles were characterized by XRD, SEM, FT-IR, and VSM techniques. The formation of strontium hexaferrite and its crystallite size in presence of different fuels were compared. The influence of different fuels was reflected on the phase purity, morphology of the final powders as well as the magnetic properties. Magnetic measurements revealed that samples prepared by citric acid and glycine as fuel have high specific saturation magnetization and moderate coercivity, while urea and oxalic acid fuels resulted in low phase purity, and thus inferior magnetic properties.
11.	Durmus, Z., et al. (author) Magnetic and dielectric characterization of alginic acid-Fe3O4 nanocomposite 2011 In: Polyhedron. - : Elsevier BV. - 0277-5387 .- 1873-3719. ; 30:2, s. 322-328 Journal article (peer-reviewed)abstract We have reported the synthesis of water dispersible alginic acid (AA)-Fe3O4 nanocomposites. The crystallite size was obtained as 9 +/- 2 nm from X-ray line profile fitting. As compared to the particle size of 9.2 nm obtained from TEM analysis, these particles show dominantly single crystalline nature. Dielectric analysis show that the real and imaginary parts of the permittivity of both pure AA and AA-Fe3O4 nano-composite obey the ionic polarization mechanism comprised of ionic conductivity and interfacial or space charge polarization. Magnetization measurements show that the saturation magnetization of AA-capped magnetite is significantly lower than the theoretical bulk value, partly due to the structural distortions on the surface of the particles. Moreover, magnetite does not saturate and exhibits no coercivity above a certain temperature, revealing superparamagnetic behavior of the nanocomposite above a blocking temperature, T-B. of similar to 175 K. The magnetic core size, determined by theoretical fitting to the magnetization data at room temperature, is 9.55 nm.
12.	Durmus, Z., et al. (author) Poly(vinyl phosphonic acid) (PVPA)-BaFe12O19 Nanocomposite 2012 In: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 25:4, s. 1185-1193 Journal article (peer-reviewed)abstract We present a method for the fabrication of PVPA/BaFe12O19 nanocomposite by in-situ polymerization of vinyl phosphonic acid, VPA in the presence of synthesized BaFe12O19 NPs. Nanoparticles and the nanocomposite were analyzed by XRD, FTIR, TGA, SEM, TEM, VSM, and conductivity techniques for structural and physicochemical characteristics. Nanoparticles, identified as BaFe12O19 from XRD analysis, were successfully coated with PVPA and the linkage was assessed to be via P-O bonds. Electron microscopy analysis revealed aggregation of BaFe12O19 particles and dominantly platelet morphology upon composite formation. TGA analysis revealed the composition of the nanocomposite as 65% BaFe12O19 and 35% polymer. Magnetic evaluation revealed that adsorption of PVPA anions during the preparation of the nanocomposite strongly influenced the magnetic properties resulting in much lower saturation magnetization values. DC conductivity measurements were used to calculate activation energy of PVPA/BaFe12O19 nanocomposite and it was obtained as 0.37 eV.
13.	Durmus, Z., et al. (author) Preparation of PVP (Polyvinyl Pyrrolidone)/Ba-Sr hexaferrites via gel to crystalline method 2012 In: Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry. - : Informa UK Limited. - 1553-3174 .- 1553-3182. ; 42:10, s. 1390-1397 Journal article (peer-reviewed)abstract Ba-M- and Sr-M-type hexagonal ferrites have been prepared via a sol-gel route, and the effects of adding different amounts of polyvinyl pyrrolidone (PVP) into the sol solutions. The average crystallite, size, D and σ, was obtained as for Z13 = 22 ± 2 nm and Z13-2 = 16 ± 3 nm and for Z16 = 18 ± 7 nm and Z16-2 = 17 ± 5 nm by XRD. FT-IR and TG analysis were used to prove the presence of PVP on BaFe12O19 and SrFe12O19. Based on the TGA curves the mass losses of the samples are assessed as follows: Z13 ̃15%, Z13-2 ̃25%, Z16 ̃5%, and Z16-2 ̃10%.
14.	Durmus, Z., et al. (author) Synthesis and characterization of L-carnosine coated iron oxide nanoparticles 2011 In: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 509:5, s. 2555-2561 Journal article (peer-reviewed)abstract L-Carnosine coated iron oxide nanoparticles (CCIO NPs) have been prepared via co-precipitation of iron oxide in the presence of L-carnosine. Crystalline phase was identified as magnetite with an average crystallite size of 8 nm as estimated from X-ray line profile fitting. Particle size estimated from TEM by log-normal fitting was similar to 11 nm. FTIR analysis showed that the binding of carnosine onto the surface of iron oxide is through unidentate linkage of carboxyl group. CCIO NPs showed superparamagnetic charactersitic at room temperature. The magnetic core size of superparamagnetic CCIO NPs was found slightly smaller than the size obtained from TEM, due to the presence of magnetically dead layer. Magnetization measurements revealed that L-carnosine iron oxide composite has immeasurable coercivity and remanence with absence of hysteritic behavior, which implies superparamagnetic behavior at room temperature. The low value of saturation magnetization compared to the bulk magnetite has been explained by spin canting. LDH activity tests showed slight cytotoxicity of high dose of CCIO NPs. The ac conductivity of CCIO NPs was found to be greater than that of carnosine and the effective conduction mechanism was found as correlated barrier hopping (CBH). dc activation energy of the product at around room temperature was measured as 0.312 eV which was in good agreement with the earlier reports.
15.	Durmus, Z., et al. (author) Synthesis and characterization of poly(1-vinyl-1,2,4-triazole) (PVTri)-barium hexaferrite nanocomposite 2011 In: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 406:11, s. 2298-2302 Journal article (peer-reviewed)abstract We present a method for the fabrication of PVTri-BaFe12O19 nanocomposites by in-situ polymerization of PVTri in the presence of synthesized BaFe12O19 nanoparticles. Nanoparticles, polymer and nanocomposite were analyzed by XRD, FTIR, TGA, TEM, NMR, GPC and conductivity techniques for structural and physicochemical characteristics. Crystallographic analysis revealed the phase as hexaferrite and X-ray line profile fitting yielded a crystallite size of 17 +/- 5 nm. Conjugation of PVTri to nanoparticle surface was assessed to be via carbonyl groups on the polymer. TG analysis revealed that 45 wt% of nanocomposite is inorganic phase (BaFe12O19). It was found out that the ac conductivity of nanocomposite under a certain frequency increases with temperature.
16.	Durmus, Z., et al. (author) Synthesis and characterization of poly(3-thiophenyl acetic acid) (P3TAA)-BaFe12O19 nanocomposite 2011 In: Polyhedron. - : Elsevier BV. - 0277-5387 .- 1873-3719. ; 30:7, s. 1349-1359 Journal article (peer-reviewed)abstract We have presented a method for the fabrication of poly(3-thiophenyl acetic acid) (P3TAA)-BaFe12O19 nanocomposites by the in situ polymerization of P3TAA in the presence of synthesized BaFe12O19 nanoparticles. The nanoparticles and the nanocomposite were analyzed by XRD, FTIR, TGA, TEM, VSM and conductivity techniques for structural and physicochemical characteristics. Crystallographic analysis revealed the phase as hexaferrite and X-ray line profile fitting yielded a crystallite size of 32 nm. The particles, observed by TEM, exhibit irregular shapes and sizes between 100 and 500 nm, revealing polycrystalline character when compared with the crystallite size from XRD. FTIR and TGA analysis results show that P3TAA is conjugated to the particle surface via a carboxylate group and that the composite has a polymer content of similar to 10%. Magnetic hysteresis curves do not saturate at high fields, which is a characteristic feature of fine particle systems with grain sizes smaller than 1 mu m. Conductivity measurements showed a semiconductor character of the nanocomposite.
17.	Durmus, Z., et al. (author) Synthesis and characterization of poly(vinyl phosphonic acid) (PVPA)-Fe3O4 nanocomposite 2011 In: Polyhedron. - : Elsevier BV. - 0277-5387 .- 1873-3719. ; 30:2, s. 419-426 Journal article (peer-reviewed)abstract Poly(vinyl phosphonic acid) (PVPA)-Fe3O4 nanocomposite is synthesized by the precipitation of Fe3O4 in the presence of PVPA. 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 PVPA around the Fe3O4 nanoparticles was confirmed by FT-IR spectroscopy, the interaction being via bridging oxygens of the phosphate and the nanoparticle surface. The crystallite and particle size were obtained as 6 +/- 2 and 8.7 +/- 0.1 nm from XRD line profile fitting and TEM image analysis respectively, which reveal nearly single crystalline nature of the Fe3O4 nanoparticles. Magnetic characterization of the bulk magnetite and (PVPA)-Fe3O4 nanocomposite reveals that both are in the superparamagnetic state at room temperature. The average magnetic domain size of the nanoparticles has been calculated using the Langevin function, which was fitted to the measured M-H hysteresis curves as 7.6 nm for the nanocomposite. In the nanocomposite, the reduction is due to the adsorption of PVPA onto the magnetite surface, which cancels some of the free spins at the surface causing a magnetically dead layer. Analysis of the conductivity and permittivity measurements revealed the coupling of ionic and polymer segmental motions and strong temperature dependency in the nanocomposite.
18.	Durmus, Z., et al. (author) The Effect of Condensation on the Morphology and Magnetic Properties of Modified Barium Hexaferrite (BaFe12O19) 2011 In: Nano-Micro Letters. - : Springer Nature. - 2150-5551. ; 3:2, s. 108-114 Journal article (peer-reviewed)abstract We present a comparison for the effect of condensation on the morphology and magnetic properties of oleic acid modified BaFe12O19 nanoparticles. Two different samples of BaFe12O19 nanoparticles were synthesized by dehydration (Z1) and rotary evaporation (Z2) method, respectively. Oleic acid was used as the surface modification agent to observe the morphological and magnetic changes. The nanoparticles were analyzed by XRD, FTIR, TGA, SEM, and VSM techniques for structural and physicochemical characteristics. Crystallographic analysis reveals the phase as hexaferrite and the average crystallite size of Z1 and Z2 is 21 +/- 3 nm and 17 +/- 2 nm, respectively. Rotary evaporator accelerates the condensation process in viscous gel (Z2). Due to the use of rotary evaporator, the coating with oleic acid for Z2 product has been accomplished very well, as compared with Z1. As a result, saturation magnetization of Z2 sample is much lower than that of Z1 sample.
19.	Durmus, Z., et al. (author) The effect of neutralizing agent on the synthesis and characterization of Mn3O4 nanoparticles 2010 In: Russian Journal of Inorganic Chemistry. - 0036-0236 .- 1531-8613. ; 55:12, s. 1947-1952 Journal article (peer-reviewed)abstract We report on the synthesis of Mn3O4 nanoparticles via a two-step hydrothermal route by using Mn(CH3COO)(2) as the only starting material and TMAOH and NaOH as hydrolysing agents. XRD and FT-IR analyses confirmed the composition and structure of Mn3O4. TEM images showed that spheroid Mn3O4 nanostructures obtained by this method have average particle size of 6 and 14 nm for NaOH and TMAOH hydrolyzed samples respectively. Particle size analysis indicated a strong aggregation of nanoparticles and exhibited bi-modal distribution with average size of aggregates as similar to 250 nm and 1.1 mu m for both samples. Zeta potential analysis revealed adsorbed TMAOH species on the surface of Mn3O4 nanoparticles hydrolyzed using TMAOH. ESR analyses resulted in broader lines and smaller g values than bulk Mn3O4 nanoparticles, probably due to the exchange-coupled system with unlike spins such as canted spin at surface of high-surface-disordered nanoparticles.
20.	Ferreira, Mjv, et al. (author) Poster Session 3 : Tuesday 5 May 2015, 08 2015 In: European Heart Journal Cardiovascular Imaging. - : Oxford University Press (OUP). - 2047-2404 .- 2047-2412. ; 16 Suppl 1 Journal article (peer-reviewed)
21.	Kavas, H., et al. (author) CTAB-Mn3O4 nanocomposites : Synthesis, NMR and low temperature EPR studies 2010 In: Polyhedron. - : Elsevier BV. - 0277-5387 .- 1873-3719. ; 29:5, s. 1375-1380 Journal article (peer-reviewed)abstract We are reporting on the synthesis of Mn3O4 nanoparticles and CTAB-Mn3O4 nanocomposites via a sonochemical route using MnCl2, ethanol, NaOH and CTAB. The crystalline phase was identified as Mn3O4. The crystallite size of the CTAB-Mn3O4 nanocomposite was identified as 13 +/- 5 nm from X-ray line profile fitting and the particle size from TEM was 107.5 +/- 1.4 nm. The interaction between CEAB and the Mn3O4 nanoparticles was investigated by FTIR and H-1 NMR spectroscopies. Two different magnetic phase transitions were observed for both samples below the Curie temperature (43 degrees C) by using a low temperature Electron Paramagnetic Resonance (EPR) technique. Also we determined the effect of the capping with CTAB on the reduction in absorbed power.
22.	Kavas, H., et al. (author) Synthesis and conductivity evaluation of PVTri-Fe3O4 nanocomposite 2010 In: Journal of Non-Crystalline Solids. - : Elsevier BV. - 0022-3093 .- 1873-4812. ; 356:9-10, s. 484-489 Journal article (peer-reviewed)abstract Poly(1-vinyl-1,2,4-triazole) (PVTri)-Fe3O4 nanocomposite with conducting character was synthesized by a wet chemical process. PVTri has been freshly synthesized and coated/adsorbed on magnetite nanoparticles that are synthesized via a sonochemical route. The structure, morphology and electrical properties of the products were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and Dielectric impedance spectroscopy, respectively. Crystallite size of magnetite was calculated by X-ray line profile fitting as 12 +/- 6 nm. FT-IR and TGA analysis confirm the adsorption of PVTri on magnetite nanoparticles. SEM micrographs revealed that Fe3O4 nanoparticles are slightly aggregated upon PVTri coating. Conductivity and permittivity measurements show the effect of glass transition temperature of polymer par in PVTri-Fe3O4 nanocomposite.
23.	Ozkaya, T., et al. (author) Reflux synthesis of Co3O4 nanoparticles and its magnetic characterization 2009 In: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 321:14, s. 2145-2149 Journal article (peer-reviewed)abstract Co3O4 nanoparticles have been prepared for the first time via reflux method, as an alternative low-temperature high-yield process, starting from one single precursor. A plausible mechanism is suggested for the synthetic process. XRD, TEM, FTIR and VSM were used for the structural, morphological, spectroscopic, and magnetic characterization of the product respectively. X-ray diffraction line profile fitting showed that average particle size of the sample is 28 nm. Morphology of the synthesized powder was observed to be thin nanosheets with a thickness of 2-3 nm based on SEM and TEM analyses. Magnetic measurements showed a deviation of the Neel temperature from the bulk value which is attributed to the finite size effects. A loop shift with an enhanced coercivity is observed in the field-cooled hysteresis loops. The opening of the hysteresis loop reveals the existence of the spin-glass like surface spins of the Co3O4 nanoparticles.
24.	Unal, B., et al. (author) L-Histidine coated iron oxide nanoparticles : Synthesis, structural and conductivity characterization 2010 In: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 505:1, s. 172-178 Journal article (peer-reviewed)abstract L-Histidine capped iron oxide nanoparticles (HCIO) have been synthesized in one pot in the presence of L-histidine. The final product was analyzed for composition, microstructure, ac-dc conductivity performance as well as dielectric permittivity. Results revealed that magnetic nanoparticles are maghemite (or magnetite) and L-histidine is covalently bonded to the nanoparticle surface via carboxyl groups. Thermal analysis revealed that magnetic nanoparticles showed catalytic effect that caused an early degradation/decomposition of the L-histidine capping. Near spherical morphology was assessed by TEM and particle size calculated from TEM analysis and crystallite size calculated from XRD analysis reveal single crystalline nature of iron oxide NPs. Magnetic measurements reveal the superparamagnetic character of the nanoparticles, hence the nanocomposite. 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 is found to obey the Arrhenius plot with activation energy of 0.934 eV. Analysis of electrical modulus and dielectric permittivity functions suggest that ionic and polymer segmental motions are strongly coupled in the nanocomposite. (C) 2010 Elsevier B.V. All rights reserved.
25.	Unal, B., et al. (author) Synthesis, conductivity and dielectric characterization of salicylic acid-Fe3O4 nanocomposite 2010 In: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584 .- 1879-3312. ; 123:1, s. 184-190 Journal article (peer-reviewed)abstract We report on the synthesis of water dispersible salicylic acid -Fe3O4 nanocomposites via a co-precipitation route by using Fe(III) and Fe(II) chloride salts, and salicylic acid. Crystalline phase was identified as Fe3O4 and the crystallite size was obtained as 13 +/- 6 nm from X-ray line profile fitting. As compared to the particle size of 20 nm obtained from TEM analysis these particles show polycrystalline nature. The capping of salicylic acid around Fe3O4 nanoparticles was confirmed by FTIR spectroscopy, the interaction being via bridging oxygens of the carboxylate and the nanoparticle surface. ac and dc conductivity measurements performed on the nanocomposite revealed semiconductor characteristics and varying trends with temperature due to reorganization of the nanocomposite. Permittivity measurements showed increasing dielectric constant with increasing temperature as expected from semiconductors. Analysis of electrical modulus and dielectric permittivity functions suggest that ionic and polymer segmental motions are strongly coupled in the nanocomposite. (C) 2010 Elsevier B.V. All rights reserved.
26.	Unal, B., et al. (author) Synthesis, dielectric and magnetic characteristics of poly(1-vinyl-1,2,4-triazole) (PVTri)-barium hexaferrite composite 2011 In: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 509:32, s. 8199-8206 Journal article (peer-reviewed)abstract The production of PVTri-BaFe(12)O(19) composites was carried out by in situ polymerization of PVTri in the presence of synthesized BaFe(12)O(19) particles. Crystalline phase was determined as BaFe(12)O(19) by XRD analysis and thermal analysis revealed an inorganic content of similar to 45% in the composite. SEM and TEM analyses showed strongly agglomerated particles in the range of 200 nm to several micrometers in the composite. The dielectric function of the various temperatures showed frequency dependency in a reciprocal power law. The dissipation (or loss) of energy stored within the composite was found to obey the reciprocal rule of power law of the frequency dependency. The real part of electrical modulus formalism increased exponentially with frequency for various temperatures, reaching a constant value and finally saturated. The imaginary part showed a reciprocal power law against the applied frequency and shifted to higher frequency at elevated temperatures. Magnetization measurements revealed substantially lower saturation magnetization of the composite material as compared to the bulk barium ferrite powders, possibly due to pinning of some of the surface spins by the adsorption of the PVTri molecules to the surface of the BaFe(12)O(19).
27.	Unal, B., et al. (author) Synthesis, structural and conductivity characterization of alginic acid-Fe3O4 nanocomposite 2010 In: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 12:8, s. 3039-3048 Journal article (peer-reviewed)abstract Alginic acid-Fe3O4 nanocomposite is synthesized by the precipitation of Fe3O4 in the presence of alginic acid (AA). Structural, surface, morphological, thermal and electrical transport properties of the nanocomposite were performed by XRD, FT-IR, TEM-SEM, TGA and conductivity measurements respectively. FT-IR analysis revealed that Fe3O4 NPs are strongly capped with AA and TGA analysis showed that nanocomposite have 80% of Fe3O4 content. TEM analysis of Fe3O4 NPs show an average particle size of 9.5 nm, and upon nanocomposite formation with AA these particles are observed to form aggregates of similar to 150 nm. The frequency-dependency of the AC conductivity show electrode polarization effect. Analysis of electrical modulus and dielectric permittivity functions suggest that ionic and polymer segmental motions are strongly coupled. DC electrical conductivity is strongly temperature dependent, and is classified into three regions over a limited temperature range of up to 100 A degrees C.

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