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Zinc oxide (ZnO) has gained great interest for two decades, and its structural, optical, and electrical properties have been investigated by scientists for technological applications. The optical properties of ZnO provide an opportunity for its application in solar cells, lasers, and light-emitting diodes. We prepared ZnO thin films with various In doping levels by using a spin coating technique, and characterised their morphological and detailed optical properties for optical applications. According to the morphological properties obtained by atomic force microscopy, the film surfaces are homogeneous and the In doping level affects the surface morphology of the films. The optical properties of the films were investigated using an ultraviolet–visible spectrometer, and some optical parameters such as band gap, refractive index, extinction coefficient, single oscillator parameters, real and imaginary functions of the dielectric coefficient, and optical conductivity were calculated and discussed in detail. The various In doping levels affected the optical properties, and the In-doped ZnO thin films can find applications in industry.

The dielectric properties of the Al/PCBM:ZnO/p-Si structure were investigated using the impedance spectroscopy technique. PCBM:ZnO layer was obtained by spin coating method on the p-Si. The morphological properties of the PCBM:ZnO were investigated using atomic force microscopy. The results highlighted that PCBM:ZnO thin film has uniform surfaces. The dielectric parameters such as real and imaginary parts of the electric modulus (M ' and M '') and ac electrical conductivity (sigma), dielectric constant (epsilon '), dielectric loss (epsilon ''), loss tangent (tan delta) values were determined. The results of the dielectric properties of the Al/PCBM:ZnO/p-Si structures impressed voltage and frequency changing. The Al/PCBM:ZnO/p-Si structures can be regarded as a candidate for organic diode applications. Selcuk University BAP OfficeSelcuk University [19401034]; Hitit University BAP OfficeHitit University [FEF.19004.15.010, FEF01.13.003] This study was supported by Selcuk University BAP Office under Project Number 19401034 and Hitit University BAP Office under Project Numbers FEF.19004.15.010 and FEF01.13.003. WOS:000617476200011 2-s2.0-85100549063

In this study nickel and boron doped sodium cobalt oxide NaCo2-xNixByO4 (0≤x≤0.3, 0≤y≤0.1) nanocrystalline thermoelectric ceramic powders were synthesized using electrospinning techniques and then consolidated into bulk ceramics. The differences in the microstructure and thermoelectric properties of the samples as a result of doping effect have been investigated. The crystalline structures of the powders and nanofibers were characterized using X-ray diffraction and scanning electron microscopy and BET Analysis before and after the calcination process at different temperatures. Nanofibers prepared by the use of electrospinning technique, have a diameter of approximately 300 nm, and the diameter of the grains of calcined powders was observed to range between 150 to 500 nanometers. Thermoelectric properties of the bulk ceramics were measured by physical properties measurement system (Lot-Oriel PPMS) in a temperature range of 15–300 K. The calculated values of dimensionless figure of merit at 300 K are 4.25×10-5, 5.3×10-6, 8.6×10-5 and 9×10-6 for sintered powders from undoped, Ni and B doped powders, respectively.

In this study 1% Ag (silver), Cu (copper), CNT (carbon nanotube) and graphene nanoribbon (GNR) nanoparticle reinforced PAN fibers were prepared and the effects of nanoparticle reinforcements upon electrical conductivity were investigated. In experimental study, graphene nanoribbon powders were produced from multiwalled carbon nanotube (MWCNT) through using the chemical approach of Hummers method. Fiber layer was dissolved at room temperature in magnetic mixer with Polyacrylonitrile (PAN) and Dimethil Formamide (DMF) which was at the rate of 10 % by mass. Thus, a viscou gel solution was obtained then nanoparticles were added to the PAN/DMF solution and the solution was vigorously stirred for one hour at room temperature. After stirring that solution was continued for 15 m in ultrasonic bath. The polymeric solution was first transferred to a 5 mL syringe, which was connected to a capillary needle with an inside diameter of 0,8 mm. A copper electrode was attached to the needle, a DC power supply produces 25 kV against a grounded collector screen distant 15cm. With the syringe pump set at 2 mL/h, the electric force overcomes the surface tension of the solution at the capillary tip, and a jet emerges. Produced fibers were collected on the rotary collector which spins at 250 rpm. Nanofiber was dried at 60 °C for 12 h in vacuum oven. Eventually, nanofiber of polyacrylonitrile (PAN) reinforced by metallic nanoparticles and graphene nanoribbon (GNR) were prepared by electro spinning process. Electrical conductivity of the obtained nanofiber were studied by measuring the electrical resistance thanks to home-made plate electrodes.

WOS: 000485002600023, Undoped and 0.1% 0.5% and 1.0% indium doped ZnO thin films were obtained by spin coating method as interfacial thin film layer between Al metal and p-Si semiconductor to investigate dielectric properties of the Al/In: ZnO/p-Si heterojunctions. Impedance spectroscopy technique was employed to characterize the dielectric properties of the Al/In: ZnO/p-Si heterojunctions depending on frequency (from 10 kHz to 1 MHz) and voltage (from - 5 V to + 5 V). The results imparted that interface states (N-ss), series resistance (R-s), barrier height (Phi(b)) and the concentration of acceptor atoms (N-a) influenced frequency changes. The dielectric parameters such as dielectric constant (epsilon'), dielectric loss (epsilon ''), loss tangent (tan delta), real and imaginary parts of the electric modulus (M' and M '') and ac electrical conductivity (sigma) values were calculated from impedance spectroscopy measurements and discussed in details for changing frequency and voltage for various In doped ZnO thin film interlayers. The dielectric properties of the Al/In:ZnO/p-Si heterojunctions were affected both In doping concentration and the frequency and voltage changes. The Al/In:ZnO/p-Si heterojunctions can be considered for industrial applications to increase the control.

International Congress on Semiconductor Materials and Devices (ICSMD) -- AUG 17-19, 2017 -- Selcuk Univ, Konya, TURKEY, WOS: 000495858400019, This paper sheds new light on how an amount of silica nanoparticles (1, 3 and 5 wt. %) acts on the morphology, the hydrophobicity and on the electrical conductivity of polyacrylonitrile (PAN) nanofibers. In this study, electrospinning technique was used to fabricate nanofibers composites consisting of PAN, dimethylformamide (DMF) and silica at two different applied voltages (15 kV and 20 kV). The scanning electron microscopy (SEM), X-ray diffraction technique (XRD), contact angle technique and the four-point probe technique were respectively used to investigate the morphology and diameter range, the crystalline structure, the hydrophobicity and the electrical conductivity of the obtained nanofibers. At the end, different results of the investigation were compared each other and discussed. (C) 2019 Elsevier Ltd. All rights reserved., Selcuk UniversitySelcuk University [BAP 17201017], Authors acknowledged a financial support received from the research fund of the Selcuk University under Grant No. BAP 17201017.

WOS: 000483376900010, We fabricated undoped and Cu doped TiO2 thin films by spin coating technique and employed the films as interfacial oxide layer between the Al and n-type Si to investigate the effect of temperature on the Al/TiO2/n-Si and Al/Cu:TiO2/n-Si devices. For that aim, the I-V measurements were performed in the range of 50 K-400 K by 50 K interval. The devices exhibited good rectifying behavior and thermal response in a wide range temperature. Ideality factor, barrier height and series resistance were calculated from I-V measurements for various temperatures by thermionic emission theory, Norde and Cheung methods and discussed in the details. The obtained results revealed that the device parameters are a strong function of the temperature. The interface states (N-ss) were affected by the changing of the temperatures. The Al/TiO2/n-Si and Al/Cu:TiO2/n-Si devices can be performed for wide range temperatures in various technological applications., Selcuk University BAP officeSelcuk University [16401044]; Selcuk UniversitySelcuk University, This work is supported by Selcuk University BAP office with Project Numbers 16401044. Authors would like to acknowledge the support of the Selcuk University for this research.

Fiber-reinforced polymer matrix composites are widely used in many structural applications thanks to their exceptional properties. In recent years, the use of electrospinning nanofibers with unique properties as reinforcement agents has attracted a great deal of attention in improving the performance of these composites. Although there are many promising studies on this subject in the literature, there are still many issues that need to be investigated. In this study, an experimental research reporting on the production and mechanical properties of two-phase polymer matrix composites reinforced with various types of thermoplastic nanofibers is presented. Nanofiber mats were produced from N66, PAN, PVA, and PVC polymers by electrospinning technique. Composites were obtained by embedding these nanofibers into epoxy resin by using vacuum infusion process. Mechanical properties of the composites were determined by performing tensile tests and the results were compared. The morphologies of nanofibers and the fracture surfaces of the composites were examined with SEM. Finally, statistical evaluations were carried out using mechanical data. According to tensile test results, the best ultimate tensile strength of 38.04 ± 3.7 MPa, elongation of 2.46 ± 0.4 % and toughness of 532 ± 137 kJ/m3 were obtained from N66 nanofiber composite, while PVA nanofiber composite was the most favorable in terms of Young's modulus (2.40 GPa). It was observed that the polymer type significantly affected the performance of the composite. In addition to the best mechanical properties, N66 composite was found to be more stable and reproducible than other specimens. Due to the good impregnation of nanofibers, it was conclusively determined that the use of vacuum infusion process is suitable for the production of these materials.

In order to determine the surface states (Nss), series resistance (Rs), and (Cu:TiO2) interlayer effects on the electrical characteristics of the Al/Cu:TiO2/n-Si metal oxide semiconductor (MOS) capacitors, both capacitance (C) and conductance (G) values were measured for frequency ranges of 10 kHz–1 MHz and ±5 V voltage ranges. In addition, to know Cu doping concentration effect on the MOS capacitor, the Al/Cu:TiO2/n-Si was fabricated with various rates Cu:TiO2 interlayer (5, 10, 15%) grown on n-Si susbtrate by spin-coating. The increase in capacitance via decreasing frequencies was attributed to the existence of Nss and their relaxation time. The frequency dependent diffusion potential (Vd), doping of donor atoms (Nd), Fermi energy (EF), barrier height (Фb) and depletion layer width (Wd) values were extracted from the linear part of reverse bias C−2-V curves. While the value the Rs decreased with increasing frequency, the Nss values increased for the three MOS capacitors. The profiles of Nss and Rs depending on voltage were also plotted by Nicollian-Brews methods and using high-low frequency (CHF-CLF) capacitance, respectively. The mean values of Nss for three capacitors were found at about 1012 eV−1cm−2 as suitable electronic devices. The lower values of the Nss can be attributed to passivation effect of Cu:TiO2 interlayer.

In this study mechanical and thermal properties of epoxy resin reinforced withdifferent numbers of nanofiber layers which produced with electrospinning method wasinvestigated. Solution of 10 wt% of polyacrylonitrile (PAN) in N,N-dimethylformamide(DMF) was used for electrospinning. The diameters of the obtained nanofibers were in therange of 380-420 nm. The average thickness of the produced nanofiber layer was about200 ?m. The special molds were prepared to produce the laminated composite plates. Thetensile tests show that the using of nanofiber PAN layers increase the tensile force 34.54%and decrease the elongation 8.87% in comparison with neat epoxy. The fracture surfaces ofthe specimens were inspected by using optical and scanning electron microscopy (SEM).The thermal properties of the nanofiber layered composites were determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. It wasobserved that the glass transition temperature increased parallel to this as the number ofPAN layers increased and rose up to 86?C, while the thermal stability did not show mucheffect of PAN layers., Bu çalışmada elektrospin metodu ile üretilmiş farklı sayılardaki nanofiber takviyelitabakalı epoksi kompozitlerin mekanik ve termal özellikleri araştırılmıştır. Elektrospinişlemi için ağırlıkça %10 oranında poliakrilonitril (PAN) ve N,N dimetilformamid (DMF)çözeltisi kullanılmıştır. Elde edilen nanofiber çapları 380-420 nm aralığındadır. Üretilennanofiber tabaka kalınlığı ortalama 200 ?m’dir. Tabakalı kompozit plakaları elde etmekiçin özel kalıplar hazırlanmıştır. Çekme deney sonuçları nanofiber tabaka kullanımınınçekme kuvvetini saf epoksiye oranla % 34.54 arttırdığı ancak uzamayı saf epoksiye oranla% 8.87 azalttığı belirlenmiştir. Numunelerin kırılma yüzeyleri optik ve taramalı elektronmikroskopu (SEM) ile incelenmiştir. Üretilen nanofiber tabakalı kompozitlerin termalözellikleri termal gravimetrik analiz (TGA) ve diferansiyel taramalı kalorimetre (DSC)analizleri ile belirlenmiştir. Camsı geçiş sıcaklığının PAN tabaka sayısı arttıkça buna paralelolarak arttığı ve 86 C ye kadar çıktığı, termal kararlılıkta ise PAN tabakalarının etkisininçok fazla olmadığı görülmüştür.