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Öğe Crystallographic, structural, optical, and dielectric properties of aniline and aniline halide imprinted hydrogels for optoelectronic applications(Springer, 2023) Yalcin, Orhan; Coskun, Ramazan; Okutan, Mustafa; Oncan, Mehmet; Yesilot, GurselThis study examines the availability of aniline and aniline halide imprinted hydrogels for technological applications through crystallographic, structural, optical, and dielectric studies. Their optical band gap and ultraviolet-visible (UV-Vis) absorption spectra have been performed in the wavelength range of 190-900 nm. The dielectric properties, energy loss tangent/ dissipation factor (tand), and complex electric modulus were characterized at room temperature and a frequency range of 100 Hz to 100 MHz. The results suggest that the complex dielectric constant and modulus are related to Kroop's theory, Brownian motion in viscoelastic systems, and Maxwell-Wagner theory. Conductivity parameters and negative s-parameter values were obtained, providing insight into the conductivity mechanism of the samples. The Cole-Davidson plots of the complex dielectric constant and the Cole-Davidson plots adapted to Smith Chart diagrams were obtained to observe the sufficiency of the samples in electronic circuit applications. Overall, the study provides a detailed analysis of the dielectric, morphological, and optical properties of aniline and aniline halide imprinted hydrogels, demonstrating their potential for technological applications.Öğe Electromagnetic properties in the structure of Cerium-Copper substituted barium hexaferrite(Elsevier, 2022) Yener, Tuba; Araz, Isa; Kirsoy, Ahmet; Yalcin, Orhan; Okutan, Mustafa; Bolivar, Peter HaringIn this study Ce3+ -Cu2+ doped barium hexaferrite Ba-0.5 Ce0.5CuFe11O19 composite sample was synthesized by a conventional method and barium hexaferrites/CeO2 phase composition, X-Ray Diffractometer were examined. Sample morphology was observed by SEM. A VSM was used to analyze the magnetic properties of the ferrites. Complex permittivity, permeability, reflection loss, absorption loss and shielding effectiveness were analyzed by using a VNA measuring the transmission/reflection coaxial airline method. The phase changes of the crystal structure because of the effect of Ce3+ ions into Ba2+ site and Cu2+ ions into Fe3+ areas were investigated. The resulting composition in these two resonance phases has a maximum absorption loss value at similar to 6.48 GHz and similar to 11.25 GHz and a maximum reflection loss value at the same frequencies. In this synthesized composition structure, it has been observed that it has a maximum reflection loss value of approximately -22.2dB and the highest shielding effectiveness value of 33.3 dB at microwave frequency 11.25 GHz. (c) 2022 Elsevier B.V. All rights reserved.Öğe Equivalent device and optical band gaps analysis of acidic red dye imprinted hydrogels(Springer, 2022) Coskun, Ramazan; Okutan, Mustafa; Yalcin, Orhan; Ozturk, Muhittin; Kirsoy, Ahmet; Oncan, MehmetStructural, optical and dielectric properties of high quality hydrogels with different doses acidic red dye imprinted were successfully analyzed in detail in this work into provide important information about the technological applications. Absorbance spectra and their energy band gaps for the acidic red dye imprinted hydrogels have been analyzed with UV spectroscopy. The complex dielectric constant, the tangent/dissipation factor (tan delta), the complex impedance, the capacitance and the complex electric modulus were measured in the frequency range of 100 Hz to 40 MHz at room temperature. It has been determined that the peak values of the tangent value in the AR doped samples in the high frequency region are due to the anionic dye effect, unlike the cationic dye doped samples. The dominant effects such as the complex dielectric constant and electric modulus in high frequency region for acidic red dye imprinted hydrogels have been attributed to the Maxwell-Wagner theory, the basis of Kroop's approach and the ionic conductivity. Experimental plane plots (Cole-Cole plots) of the complex dielectric constant, impedance and electric modulus for different doses acidic red dye imprinted hydrogels were obtained. In order to analyze the suitability of the samples for electrical circuit applications, the equivalent electrical circuit corresponding to the Cole-Cole plots for the complex electric modulus was calculated and adapted with Smith Chart.Öğe Fabrication and Applications of Metal Nanowire Arrays Electrodeposited in Ordered Porous Templates(INTECH EUROPE, 2010) Kartopu, Giray; Yalcin, Orhan; Lupu, N[Abstract Not Available]Öğe Fullerene C60: Dielectric and elastic properties of E8 nematic liquid crystal(Elsevier, 2024) Okutan, Mustafa; Ozturk, Muhittin; Yesilot, Gursel; Yalcin, Orhan; Bolivar, Peter HaringThis study presents a comprehensive analysis of the impact of Fullerene C60 doping on the dielectric and elastic behavior of E8 coded nematic liquid crystals. By investigating the underlying mechanisms, we unveil how Fullerene C60 can effectively modify the properties of nematic liquid crystals, particularly their dielectric and elastic characteristics. Through the analysis of Cole-Cole plots and semicircle plots, we gain valuable insights into the suitability of an equivalent electronic circuit model, thereby holding promise for liquid crystal-based devices with improved performance and functionality in electrical circuit applications. Furthermore, our results demonstrate that the presence of Fullerene C60 induces higher splay elastic constant (K11) values in doped nematic liquid crystals, attributed to an increase in the sample's threshold voltage. Moreover, the presence of Fullerene C60 fosters strong elastic interactions in the liquid crystal system due to surface anchorage, resulting in an elevation of its elastic energy.Öğe Hysteretic behavior of quadrupolar ordering in a 2D magnetic spin-1 Ising nanoparticle(Elsevier, 2021) Erdem, Riza; Yalcin, Orhan; Ozum, Songul; Sahin, Ayse; Demirer, NazliPair approximation technique has been used to study the quadrupolar ordering properties for the 2D magnetic spin-1 Ising nanoparticles, consisting of core and surface parts with an interface coupling. Similar to the magnetic hysteresis, it has been shown that the quadrupole order parameter (Q) as a function of single-ion anisotropy (D) has a 'hysteresis' character which is generally called quadrupole (or QD) hysteresis. The observed QD loops strongly depend on temperature (T), external magnetic field (H) and biquadratic exchange interaction (K). Shifted QD loops with an asymmetry are found when H and K values are increased. These behaviors are also discussed in relation to other theoretical findings.Öğe Hysteretic dipolar and quadrupolar properties of the spin-1 Blume-Emery-Griffiths model under pair approximation(World Scientific Publ Co Pte Ltd, 2021) Ozum, Songul; Erdem, Riza; Yalcin, Orhan; Gorguluer, OmerAs a continuation of previously published work [A. Erdinc and M. Keskin, Int. J. Mod. Phys. B 18, 1603 (2004), doi:10.1142/S0217979204024823] the hysteretic properties of magnetization (m) and quadrupolar moment (q) have been investigated for the spin-1 Blume-Emery-Griffiths model using pair approximation. The magnetic field (h) dependence of m is produced for different values of the lattice coordination number (z), biquadratic interaction (k) and single-ion anisotropy (d). The (m,h) loops show different and novelty properties when d < 0. We also observed the hysteresis cycles in the (q,d), (q,h) and (m,d) planes. These curves strongly depend on biquadratic interaction k. Our results are found to be in good agreement with the other theoretical findings.Öğe Impedance characterization of hydrothermally synthesized nickel zinc ferrite nanoparticles for electronic application(Elsevier, 2024) Okutan, Mustafa; Ozturk, Muhittin; Okutan, Sonay; Yesilot, Gursel; Yalcin, Orhan; Bablich, Andreas; Bolivar, Peter HaringThis study comprehensively investigates the structural, morphological, dielectric, and conductivity properties of Ni0.5Zn0.5Fe2O4 nanoparticles synthesized through a hydrothermal method, focusing on their suitability for technological applications. The nanoparticles exhibited a cubic structure with an average grain size of approximately 19 nm. The dielectric properties were analyzed with respect to frequency and temperature, showcasing behaviors consistent with Maxwell-Wagner and Koop's theories. The dielectric plane plots, corresponding to the impedance circuit in the Smith Chart, were found to align with the Davidson-Cole relaxation model. Moreover, the conductivity properties adhered to the Jonscher Power law, resembling conductive properties akin to semiconductors in accordance with the band theory. Notably, the s parameter, indicative of the DC conduction mechanism, displayed temperature-dependent variations, suggesting compatibility with the small polar and correlated hopping barrier conduction models. The thermal activation energies of the Ni0.5Zn0.5Fe2O4 nanoparticles at 102, 103, 104, 105, and 106 rad/s frequencies have been recorded at 0.115, 0.141, 0.157, 0.133 and 0.121 eV, respectively. The experimental results strongly suggest that Ni0.5Zn0.5Fe2O4 nanoparticles hold promise as an inspiring material for electronic circuit applications.Öğe Impedance spectroscopy of polyaniline coated hydrogel(Springer, 2021) Okutan, Mustafa; Yavuz, Erdem; Ozerol, Esma Ahlatcioglu; Senkal, B. Filiz; Yalcin, Orhan; Yildiz, AlptekinA sulfonic acid functional hydrogel was prepared starting from the copolymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid as monomer and tetraallyl ammonium bromide as a cross-linking agent in the presence of K(2)S(2)O(8)as a radical initiator. Aniline was interacted with the hydrogel, and oxidative polymerization reaction of anilinium sulfonate salt containing hydrogel was performed by using ammonium persulfate to obtain conducting gel material. The electrical/dielectric properties of the PANI-coated hydrogel were analyzed using impedance spectroscopy. The frequency dependence of the real (epsilon ') and imaginary (epsilon '') parts of the dielectric constant (epsilon), dissipation factor, the real (sigma ') and imaginary (sigma '') parts of the ionic conductivity (sigma), Cole-Cole plots and impedance parameters values for the PANI-coated hydrogel were analyzed in the frequency range of 100 Hz-15 MHz at room temperature. PANI-coated hydrogel shows the non-Debye relaxation type in the materials. The conductivity mechanisms of PANI-coated hydrogel are super linear power law and extended pair approximation.Öğe Investigation of capacitors and electrical circuit elements performance of magnetic biocomposites prepared by using the hemp biomass(Elsevier Science Sa, 2023) Coskun, Ramazan; Yalcin, Orhan; Okutan, MustafaHemp biomass (HB) was brought into activated hemp biomass (AHB) by chemical technique and all samples were obtained by doping different nanoparticles. Structural, dielectric and magnetic characterizations for all samples were performed by using the XRD, FTIR, SEM, EDX, LCR Meter and PPMS at room temperature. The characteristics of both hemp biomass and nanoparticles in the structures of these samples were examined in detail. In addition to HB and AHB samples, the contribution of lignin and pectin characteristic bands to con-ductivity was investigated in AHB samples doped with Fe3O4, MgFe2O4 and SrFe2O4 nanoparticles. It has been determined that homogeneously dispersed nanoparticles contribute to surface area, crystallization and con-ductivity and these samples are technological products. It was determined that the samples could be used as batteries, and two electrical circuits simultaneously connected to the lignin and pectin structures of the activated hemp biomass (AHB) doped with different types of nanoparticles were obtained from the Smith-Chart diagram.Öğe Magnetic and transport properties of chemical solution deposited (100)-textured La0.7Sr0.3MnO3 and La0.7Ca0.3MnO3 nanocrystalline thin films(IOP PUBLISHING LTD, 2011) Kartopu, Giray; Yalcin, Orhan; Demiray, A. SerdarA study of the magnetic and electrical properties of (100)-oriented La-0.7(Sr,Ca)(0.3)MnO3 thin films prepared by an optimized chemical solution deposition process on a (100) SrTiO3 single-crystal substrate is reported in this paper. The films were studied by high-resolution scanning electron microscopy, x-ray diffraction, vibrating sample magnetometer, ferromagnetic resonance and four-point-probe electrical measurements. A characteristic nanocrystalline texture with similar to 15 nm crystallites is observed in both films. Remarkably, the resistivities of these films are three orders of magnitude smaller compared with unoptimized films grown even on the same substrate. The magnetotransport properties were determined as a function of temperature and applied field magnitude, and compared with bulk crystals and vacuum-deposited single crystalline (epitaxial) thin films as well as manganite nanostructures reported in the literature. Both films display large values of colossal magnetoresistance at around room temperature. Significantly, the magnetoresistance in (100) La0.7Sr0.3MnO3 thin film is observed to be highly linear even at low fields near the metal-insulator transition temperature. However, the dependence of these promising properties on the nanocrystal size remains to be explored.Öğe Nonequivalent Antiferromagnetically Coupled Sublattices Induce Two-Step Spin-Crossover Transitions: Equilibrium and Nonequilibrium Aspects(Mdpi, 2024) Veliu, Valon; Yalcin, Orhan; Ozum, Songul; Erdem, RizaAs a continuation to the previously published work (Yal & ccedil;& imath;n et al. (2022)), we investigate the equilibrium and nonequilibrium properties of the spin-crossover systems, with a specific focus on the nonequivalent sublattice, and compare these properties with those of the equivalent sublattices. We used the lowest approximation of the cluster variation method (LACVM) to derive the static equations for the order parameters of the two sublattices and determine high-spin fraction in relation to temperature and external magnetic field in a spin-crossover system. At a low temperature, the transition from stable high-spin (HS) state where nHS=1 occurs in the plateau region, where nHS=0.5 for nonequivalent sublattices. The order parameters for non-equivalent sublattices exhibit different states at the transition temperature. Also, we study the nonequilibrium properties of the order parameters and high-spin fraction using the path probability method (PPM). With the current model, we obtain and analyze the relaxation curves for the order parameters Sa, Sb, and high-spin fraction. These curves demonstrate the existence of bistability at low temperatures. At the end of this study, we present the flow diagram that shows the order parameters for different temperature values. The diagram exhibits states that are stable, metastable, and unstable.Öğe Origin of the exchange bias training effects in magnetically coupled soft/hard synthetic bilayers at low temperature(ELSEVIER SCIENCE BV, 2015) Yalcin, Orhan; Unluer, Sahin; Kazan, Sinan; Sahingoz, RecepHysteresis loops of the nanoscale magnetic layer Co90Fe10 and Ni81Fe19 and bilayer Co90Fe10/Ni81Fe19 and Ni81Fe19/Co90Fe10 films were measured as a function of external dc magnetic Field and the thickness dependence of these Films were plotted as a function of temperature. Time evolution of the minor/middle/major hysteresis loops of 5/5 nm-thick Ni81Fe19/Co90Fe10 monolayer have been observed at 10 K. The spin valve, exchange bias training and Barkhausen effects for magnetic layer and bilayer films have been analysed at various temperatures, thicknesses and different orientations according to the substrate. The exchange-bias training effects have been observed only in positive magnetization region. Origin of the exchange-bias training effects and asymmetric hysteresis loops are related to the relaxation mechanism of a pinning layer in magnetically coupled soft/hard bilayers. (C) 2014 Elsevier B.V. All rights reservedÖğe Origin of the martensitic and austenitic phase transition in core-surface smart nanoparticles with size effects and hysteretic splitting(AMER INST PHYSICS, 2014) Yalcin, Orhan; Erdem, Riza; Ozum, SongulBlume-Emery-Griffiths model is used to study the effects of the bilinear and biquadratic exchange interactions as well as crystal field interaction on the magnetic properties of core-surface smart nanoparticles. From the minimization of the free energy in pair approximation in Kikuchi version, a set of equations for the bond variables and magnetization are derived. Based on the numerical solutions of these equations, magnetization and hysteresis curves are obtained. Besides the first-and second-order phase transitions, martensitic and austenitic phase regions are observed in the phase diagrams of homogeneous and composite nanoparticles and the origin of martensitic transitions (MT)-austenitic transitions (AT) is investigated. It is found that MT-AT occurred for a nonzero biquadratic exchange parameter. On the other hand, nonzero single-ion anisotropy caused the hysteretic splitting in core-surface type nanoparticles. Martensitic and austenitic results of nanoparticles agree with the experimental results in literature. (c) 2014 AIP Publishing LLC.Öğe Origins of the Exchange-Bias Phenomenology, Coercivity Enhancement, and Asymmetric Hysteretic Shearing in Core-Surface Smart Nanoparticles(HINDAWI LTD, 2016) Erdem, Riza; Yalcin, Orhan; Ozum, Songul; Ciftci, NazireWe have used a spin-1 Ising model Hamiltonian with dipolar (bilinear, J), quadrupolar (biquadratic, K), and dipolar-quadrupolar (odd, L) interactions in pair approximation to investigate the exchange-bias (EB), coercive field, and asymmetric hysteretic shearing properties peculiar to core/surface (C/S) composite nanoparticles (NPs). Shifted hysteresis loops with an asymmetry and coercivity enhancement are observed only in the presence of the odd interaction term in the Hamiltonian expression and their magnitudes show strong dependence on the value of L. The observed coercivity and EB in C/S NPs originated from nonzero odd coupling energies and their dependence on temperature (T) and particle size (R) are also discussed in relation to experimental findings.Öğe Spin-flop transition, magnetic and microwave absorption properties of alpha-Fe2O4 spinel type ferrite nanoparticles(ELSEVIER SCIENCE BV, 2013) Yalcin, Orhan; Bayrakdar, Harun; Ozum, SongulWe have prepared NiFe2O4, CoFe2O4, Ni0.6Zn0.4Fe2O4 and ZnFe2O4 spinel type ferrite nanoparticles by surfactant-assisted hydrothermal process using cetyltrimethylammonium bromide (CTAB). The spin-flop transition, magnetic, dielectric and permittivity characterizations have been investigated. The spin-flop transition occurs from antiferromagnetic state to mixed state and then ferromagnetic state for Zn doped samples. The spin-flop transition occurs in the temperature range of 50-250 K. The ionic conduction, dipolar relaxation, atomic polarization and electronic polarization are the main mechanisms that contribute to the permittivity of a dielectric material. The permittivity increases with increasing frequency. This suggests a resonance behavior, which is expected when the ferrite samples are highly conductive and skin effect become significant. These samples will provide great benefits for electromagnetic applications and electromagnetic interference shielding characteristics. (C) 2013 Elsevier B.V. All rights reserved.Öğe Spin-lattice relaxation within a dimerized Ising chain in a magnetic field(AMER INST PHYSICS, 2014) Erdem, Riza; Gulpinar, Gul; Yalcin, Orhan; Pawlak, AndrzejA qualitative study of the spin-lattice relaxation within a dimerized Ising chain in a magnetic field is presented. We have first determined the time dependence of the deviation of the lattice distortion parameter delta Delta from the equilibrium state within framework of a technique combining the statistical equilibrium theory based on the transfer matrix method and the linear theory of irreversible thermodynamics. We have shown that the time dependence of the lattice distortion parameter is characterized by a single time constant (tau) which diverges around the critical point in both dimerized (Delta not equal 0) and uniform (Delta = 0) phase regions. When the temperature and magnetic field are fixed to certain values, the time tau depends only on exchange coupling between the spins. It is a characteristic time associated with the long wavelength fluctuations of distortion. We have also taken into account the effects of spatial fluctuations on the relaxation time using the full Landau-Ginzburg free energy functional. We have found an explicit expression for the relaxation time as a function of temperature, coupling constant and wave vector (q) and shown that the critical mode corresponds to the case q = 0. Finally, our results are found to be in good qualitative agreement with the results obtained in recent experimental study on synchrotron x-ray scattering and muon spin relaxation in diluted material Cu1-yMgyGeO3 where the composition y is very close to 0.0209. These results can be considered as natural extensions of some previous works on static aspects of the problem. (C) 2014 AIP Publishing LLC.Öğe Structural, morphological and dielectrical properties of acorn cupule extract doped hydrogels(Elsevier, 2024) Gorguluer, Omer; Coskun, Ramazan; Yalcin, Orhan; Okutan, Mustafa; Uslu, Hasan; Doganay, B. SeymaAcorn cupule extract doped different hydrogels were prepared to examine their structural morphological and dielectrical properties at room temperature. Structural, morphological and dielectrical parameters for all samples were found by using the XRD, SEM, EDX and impedance spectroscopy. The conductivity, capacitive effect and electronic circuit properties for acorn cupule extract doped hydrogels have not studied before in the literature. Therefore, the complex impedance, capacitance, phase angles, dielectric constant, tangent factor, electric modulus and frequency evolution of ionic conductivity (s -parameters) were successfully analyzed in detail using impedance spectroscopy in the frequency range of 10 2 to 10 7 rad/s at RT. Furthermore, the Cole -Cole plots of the dielectric constant adapted to the Smith chart and general RC equivalent circuit was showed in detail. It was determined that the dielectric effect was at its highest values in the frequency range of 10 2 to 10 5 rad/s.Öğe Synthesis and investigation of small g-values for smart spinel ferrite nanoparticles(Elsevier Science Sa, 2021) Bayrakdar, Harun; Yalcin, Orhan; Ozum, Songul; Cengiz, UgurSmart spinel and hexagonal ferrite nanoparticles (NPs) have been fabricated by ethylenediaminetetraacetic acid (EDTA) and cetyltrimethylammonium bromide (CTAB) assisted hydrothermal route by using NaOH solution. Electron spin resonance (ESR) measurements of the spinel and hexagonal ferrite NPs have been performed by a high sensitive conventional x.band (similar to 9.5-9.8 GHz) spectrometer at room temperature (RT). The measured five small g-values by ESR spectra at RT may be relevant for quantum information processing. Quantum computing and relativistic quantum computing by two-level system (qubit) have been realized by spinel type NPs at RT. Temperature evolution of magnetic hysteresis loops, magnetization, coercivity (H-C), saturation field (H-S), saturation magnetization (M-S) and remanent magnetization (M-r) have been investigated. (C) 2021 Elsevier B.V. All rights reserved.Öğe The phase diagrams with influence of biquadratic exchange coupling on martensitic-austenitic transformations for core-surface nanoparticles(ELSEVIER SCIENCE BV, 2015) Yalcin, Orhan; Erdem, Riza; Ozum, Songul; Demir, ZaferRecently, origin of the martensite-austenite transitions in core-surface type magnetic nanoparticles has been investigated theoretically and it has been indicated that repulsive biquadratic exchange coupling (K < 0.0) causes the coexisting martensite and austenite phases. In the present paper, the phase diagrams of homogeneous and composite nanoparticles in the k(B)T/J(0)-D/J(0) plane are studied for the presence and absence of attractive biquadratic exchange interaction in addition to repulsive biquadratic exchange interaction. Significant changes in the phase diagram points are discussed in the presence of martensitic and austenitic transformations. Four regions in the phase diagrams are found as second-order, martensitic-austenitic, T-cid and first-order phase transition regimes. (C) 2015 Elsevier B.V. All rights reserved.
