Kök, Mediha; Çirak, Z Deniz; Aydin, Handan; Coşkun, Meltem

In this study, poly(ϵ-caprolactone) (PCL)-based nanocomposite films reinforced with a Fe–35%Ni alloy, which possesses a low coefficient of thermal expansion and distinct magnetic properties, were produced. The composites were prepared using the solvent casting method, with the Fe–Ni alloy incorporated into the PCL matrix at different weight ratios (10%–50%). The structural, morphological, thermal, and magnetic properties of the resulting nanocomposites were comprehensively investigated using FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), SEM (scanning electron microscopy/energy dispersive x-ray spectroscopy), differential scanning calorimetry, TGA (Thermogravimetric analysis) ve (vibrating sample Magnetometry). FTIR results indicated that the Fe–Ni addition does not form chemical bonds with the PCL matrix and that the composite structure is formed through physical interactions. XRD analyses confirmed that the semi-crystalline structure of PCL is preserved and that the Fe–Ni alloy exhibits a face-centered cubic (FCC) crystal structure. SEM images revealed that while a homogeneous distribution is achieved at low doping levels, partial agglomeration occurs at high levels. Thermal analyses showed that Fe–Ni particles increase the degree of crystallization through a nucleation effect and provide a significant increase in melting temperature and crystallinity values, particularly in the 10%–40% range. TGA results revealed that the thermal stability of the composites increased and their decomposition behavior became multi-stage. Magnetic measurements showed that the saturation magnetization increased significantly with increasing Fe–Ni content, and the composites acquired ferromagnetic character. Furthermore, it was determined that the developed composites exhibit distinct shape memory behavior and can return to their original form upon thermal stimulation. The findings indicate that Fe–35%Ni-doped PCL nanocomposites are a promising candidate for multifunctional applications due to their enhanced thermal, magnetic, and smart material properties.

İncele

Deniz Çirak, Zehra; Aydin, Handan; Coşkun, Meltem; Kök, Mediha

In this study, magnetic polymer nanocomposites based on PCL/PVA PCL(Polycaprolactone)-PVA(Polyvinyl alcohol) (80/20) reinforced with Fe2O3 and Fe3O4 nanoparticles were successfully produced, and their thermal, structural, morphological, and magnetic properties were comparatively investigated. The systematic evaluation of the effects of Fe2O3 and Fe3O4 additions on the same biodegradable polymer matrix at 20% and 40% loading levels constitutes the main novelty of this study. The nanocomposites were characterized using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and physical property measurement system (PPMS) analyses. The TGA results demonstrated that the decomposition onset temperature increased with the addition of nanoparticles and, particularly in the composite with 40% Fe3O4 content, the residual mass reached 15.81%, indicating a significant improvement in thermal stability. DSC analyses showed that the melting peak temperature increased at high loading levels and that Fe2O3 loading supported crystallization more than Fe3O4. FTIR and XRD results confirmed that the nanoparticles dispersed successfully in the polymer matrix without forming chemical bonds and provided strong interfacial interactions. The SEM images revealed a homogeneous distribution at low loading levels, while significant agglomeration formed at high Fe3O4 content. Magnetic measurements indicated that the pure PCL/PVA blend exhibited diamagnetic behavior, Fe2O3-containing composites displayed hard ferromagnetic behavior, and Fe3O4-containing composites exhibited soft ferromagnetic behavior. The highest saturation magnetization of 10.4 emu/g was obtained in the composite with 40% Fe3O4 content. The findings indicate that Fe2O3- and Fe3O4-doped PCL/PVA nanocomposites are functional materials with high potential for applications in sensors, actuators, magnetically controlled systems, and biomedical applications.

İncele

Aydin, Handan; Odak, Mehmet

In this study, the structural and optical properties of CdO thin films subjected to heat treatment at different temperatures were investigated. CdO films were deposited on glass substrates by thermal evaporation. X-ray diffraction technique (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and atomic force microscopy (AFM) measurements were taken to investigate the crystal structure and surface morphology of the prepared films UV-vis spectrometer was utilized to measure the optical properties. As a result of XRD measurements, it was observed that the CdO thin film without and with heat treatment has a cubic crystal structure. The increase in the sharpness of x-ray peaks in CdO thin films with heat treatment means an increase in crystallization, and the calculated crystal sizes showed that the crystal size generally tends to increase with a rise in the applied annealing temperature. As can be seen from the SEM images, it was observed that the small grains on the surface were replaced by large grains as a result of the merger of small grains with each other with rising annealing temperature. The optical band gap Eg, which changes with heat treatment, was calculated to be between 2.45 and 2.27 eV. It was concluded that heat treatment improves the conductivity of CdO thin films by reducing the Eg value.

AtıfScopus1·WoS1·OpenAlex3

İncele

Aydin, Handan

Bu çalışmada poly (-caprolactone) (PCL) ile Poli(vinil klorür) (PVC-N3) blendleri üretilmiş olup, ZnO yarıiletken ilavesi ile oluşan kompozit araştırılmıştır. Öncelikle PCL ve PVC-N3 uygun bir çözelti içerisinde homojenizatör yardımıyla uzun süre ka-rıştırılarak elde edilmiştir. Ayrı bir yerde aynı çözücü ile karıştırılan ZnO hazırlanan blende eklenerek, değişen ZnO oranına göre polimer karışımında meydana gelen fark-lılıklar incelenmiştir. %5, %10, %15 oranlarında ZnO yarıiletkeni eklenmiştir. Hazır-lanan numunelerin yapısal sonuçları XRD ve SEM analizleri ile incelenmiştir. ZnO katkılı kompozitlerinin optik özellikleri UV-VIS spektrometresi ile karakterize edil-miştir. Numunelerin XRD (X-ışını Difraksiyonu) spektrumlarında hekzagonal wurtzite yapılı ZnO’in varlığını göstermiştir. SEM (Taramalı Elektron Mikroskopu) analizle-rinde ise yapıda kümelenmenin artması görülmüş olup; polimer blendinin katkıyla yüzey pürüzlülüğünü değiştirdiğini göstermektedir. Buna ilaveten; PCL+PVC-N3 karı-şımının ZnO ile optiksel etkileşimi UV-Vis spektroskopisi kullanılarak incelenmiştir. UV-Vis ölçümleri kullanılarak numunelerdeki yasak enerji aralıklarındaki değişmeler çeşitli uygulamalar için iyileştirme gösterecek şekilde belirlenmiştir. ZnO-PCL+PVC-N3 kompositlerinin optik enerji bant aralıkları artan katkı içeriğiyle değişiklik gösterdiği görülmüştür.

İncele

Aydin, Handan; Sait Kanca, M.; Kök, Mediha; Taşgin, Yahya; Tatar, Beyhan

Thin film technology aims to improve and develop the properties of materials by coating technology. In this study, thin films consisting of rare earth element and selenium semiconductor material, which have recently been preferred in technological applications due to their important properties, are examined. Selenium thin films doped with Ho2O3 and Dy2O3 rare earth oxides (REO) were fabricated on glass substrate by thermal evaporation method. The surface morphology and optical properties of the thin films were investigated. As a result of surface morphology examinations, it was determined that homogeneous thin films were obtained and the thickness of the thin films varied between 20 and 30 μm. In addition, the roughness value of the glass substrate decreased as a result of coating with doped selenium thin film. The band energy value obtained by UV-VIS measurements decreased compared to glass and was close to the selenium element value. In the comparison between selenium coatings doped with Ho2O3 and Dy2O3, a notable reduction in the Eg value was observed specifically in the Ho2O3 doped coatings.

AtıfScopus3·OpenAlex3

İncele

Aydin, Handan; Torgut, Gülben

In this study, firstly, the copolymer of acrylonitrile (AN) and styrene (St) was synthesized by solution polymerization method using 2,2′-azobisisobutyronitrile (AIBN) as an initiator. The composites of copolymer incorporating lanthanum (III) chloride (3, 6, 9 and 18 wt%), the rare earth element (REE), were prepared and thin films were produced by thermal evaporation method for optical measurement. The samples were characterized by attenuated total reflectance Fourier transform infrared (ATR–FTIR), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) and X-ray diffraction (XRD). The glass transition temperature, which is one of the thermal properties of the synthesized copolymers and composites, was examined with a differential thermal analyzer. The changes in the optical properties of the samples produced with LaCl3 dopant were investigated using the UV–VIS spectroscopy. The optical band gaps of the samples were calculated using Tauc equation. As a result of the optical studies, it was observed that there was a change in the conductivity properties of the samples with the addition of LaCl3. The present results showed the advantage of using LaCl3 as a filler to improve the optical properties of poly(AN-co-St) samples.

İncele

Ustaoğlu, Fikret; Kutlu, Banu; Tepe, Yalçın; Aydin, Handan

The aim of this study is to detect the heavy metal contamination in the sediment of Batlama Stream and to evaluate the anthropogenic effect. Field studies were seasonally carried out in 3 stations between June 2014 and July 2015. In the sampling studies carried out in Batlama Stream, contamination factor (CF), enrichment factor (EF), potential ecological risk factor (Eri), lowest effect level (LEL), geoaccumulation index (Igeo) contamination indicators were used in order to evaluate sediment contamination. In Batlama Stream, average heavy metal level of three stations was detected in mg/dry kg in the sediment as Cr 7.08, Mn 63.62, Fe 858.04, Co 5.47, Ni 4.99, Cu 20.61, Zn 49.60, Cd 0.09, and Pb 20.68. Elements which the sediment has most are Fe, Mn, and Zn. According to EF, Pb was detected as an enriching element. Eri Pb is in the low risk group. In LEL value, the highest Pb average was found as 31. According to Igeo values, Pb is a moderate contaminant. This metal has anthropogenic sources and it is caused by domestic, agricultural, and waste waters. In the elements analysed in Batlama Stream sediment (apart from Pb), it is indicated that it is generally a clean stream and considered reference stream.

AtıfScopus3

İncele

Aydin, Handan

In this study, Yttrium Ferrite based nano electroceramics were prepared bythe doping at various ratios of graphene oxide by the hydrothermal method.The obtained doped and undoped samples were characterized by XRD, SEM,FTIR, DTA, UV-VIS-NIR spectroscopy, temperature dependent electricalresistance changes and dielectric measurements. From the XRD results, it isobserved that the obtained samples are polycrystalline with an Orthorhombicstructure. The crystal parameters are changed with the doping of grapheneoxide. FTIR spectra indicate that the graphene oxide changes the peakintensities. This confirms the incorporation of the graphene oxide into theceramic structure. The doping of the graphene oxide changes the optical bandgaps of the samples. The dielectric constants of the samples are changed withthe graphene oxide. The DC electrical conductivity measurements confirm thesemiconducting behavior of the samples. The obtained results indicate thatthe electronic and nanostructure of the synthesized electroceramics can becontrolled by the doping of graphene oxide for electronic and energyapplications.

AtıfOpenAlex10

İncele

Aydin, Cihat; Aydin, Handan; Yakuphanoglu, Fahrettin

In this study, X-ray diffraction, electrical conductivity, optical and dielectrical properties of the InTe amorphous semiconductor material have been investigated. X-ray diffraction results show that InTe sample has an amorphous structure. Temperature dependence of electrical conductivity of the sample has been investigated and the obtained results confirm that InTe is an amorphous semiconductor. The InTe sample shows photoconductivity behavior. The optical band gap and optical constants of the sample were calculated using transmittance and reflectance spectra. In the sample, the direct optical transitions take place The refractive index dispersion curve of the sample obeys the single oscillator model. The dielectrical properties of the sample have been investigated as a function of frequency and temperature. It was found that the dielectrical parameters were changed with temperature and frequency. The electrical modulus curves were used to analyze the dielectrical relaxation processes.

İncele

Aydin, Cihat; Aydin, Handan; Taskin, Mustafa; Yakuphanoglu, Fahrettin

AtıfOpenAlex19

İncele

Aydin, Handan; Gündüz, Bayram; Aydin, Cihat

In this work, we synthesized the graphene oxide by Hummers method and prepared poly-N-vinylcarbazole (PVK)/graphene oxide (GO) nanocomposites. We investigated the SEM images, FTIR and UV spectroscopy and ac conductivity properties of PVK:wt% (0, 1, 5, 10, 15%) GO nanocomposites thin films. The PVK and PVK/GO nanocomposites are dominant in near ultraviolet region. The absorption band edge of the films of the PVK/GO nanocomposites varies from 3.077 to 3.175 eV, while the allowed optical band gap of the 0, 1, 5, 10 and 15% wt. GO + PVK nanocomposites varies from 2.97 to 3.30 eV. The optical band gap and refractive indices of the PVK can be changed with increasing the percentage by weight of graphene oxide. The single oscillator energy varies from 3.358 to 3.670 eV, while the dispersion energy varies from 6.404 to 6.970 eV. The graphene oxide has an important effect on the ac conductivity of the PVK. Obtained results show that the PVK material modified with graphene oxide is promising for electronic, optical and optoelectronic technology.

AtıfScopus20·WoS20·OpenAlex22

İncele

Aydin, Handan

H-BN fiziksel özellikleri ve kimyasal kararlılığı sebebiyle geniş optik enerji bandı aralığına sahip olan bir III- V grubu bileşiğidir. Eşsiz özelliklere sahip, yapay bir malzeme olan hegzagonal bor nitrür pek çok sektörde kullanımı giderek artmaktadır. Bor nitrür, farklı metotlar ile üretilebilmektedir. Bu çalışmada, borik asitten bor oksit üretilmiş ve bor oksitin 850 °C’de nitrürlenmesi ve 1500 °C’de sinterlenmesi sonucunda hegzagonal bor nitrür (h-BN) elde edilmiştir. Üretilen hegzagonal bor nitrürün saflığını, bal peteği ve tabakalı yapısını belirlemek amacıyla XRD, SEM, FT-IR ve optik ölçümler ile karakterize edilmiştir. Numunenin XRD spektrumu, Bor Nitrür nanotozların hegzagonal BN yapıda ve polikristalin olduğunu ortaya koymaktadır. BN numune için kristal boyutu 71.2 nm olarak bulunmuştur. SEM fotoğrafları nano tanelerden oluşan yapıyı doğrulamıştır. Elde edilen sonuçlar BN numunesinin nanoyapıya sahip olduğunu göstermektedir.

AtıfTR Dizin4

İncele

Aydin, Handan

The electrical and optical properties of carbon nanotube and titanium dioxide nano-composites have been investigated. The carbon nanotubes were prepared by chemical vapor deposition. The diameters and lengths of the carbon nanotubes were respectively determined to be 20-30 nm and about 3-5 mu m by high resolution transmittance electron microscopy. The direct current electrical conductivity values sigma(dc) of the nanocomposites were found to be in the range of 5.96 x 10(-3)-0.47 S/cm. It was found that the electrical conductivity of nanocomposites increases with CNT content. The optical band gaps of the nanocomposites were determined by Kubelka-Munk theory based on the analysis of diffuse reflectance spectra. The band gap (E-g) values of the composites were decreased with increasing CNT contents. The obtained results indicate that the electrical and optical properties of TiO2 semiconductor metal oxide can be improved by incorporation of CNT content for electronic applications.

AtıfWoS6·OpenAlex11

İncele