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The C-V characteristics of TiO2/p-Si/Ag, GNR doped TiO2/p-Si/Ag and MWCNT doped TiO2/p-Si/Ag heterojunction devices
(Elsevier, 2020) Erdal, Mehmet Okan; Kocyigit, Adem; Yildirim, Murat
The TiO2/p-Si/Ag, graphene (GNR) doped TiO2/p-Si/Ag and multi-walled carbon nanotube (MWCNT) doped TiO2/p-Si/Ag heterojunction devices were fabricated by electrospinning technique at same conditions. Their structural, morphological properties, thermal analyses (TGA), and capacitance voltage characteristics were studied and compared. The undoped, GNR and MWCNT doped TiO2 structures obtained successfully according to XRD measurements. Morphological properties of the undoped, GNR and MWCNT doped TiO2 composite structures have rod or ribbon like structures. The TGA result confirmed the GNR and MWCNT doped TiO2 structures. The C-V and G-V measurements were employed for electrical characterization of the TiO2/p-Si/Ag, GNR doped TiO2/p-Si/Ag and MWCNT doped TiO2/p-Si/Ag devices for various frequencies at room temperatures. The results imparted that the capacitance and conductance behaviors of all devices are strong functions of the frequency and voltage. The electrical parameters were calculated from C-2-V plots of the heterojunction devices and compared for three devices. The transient photocapacitance plots revealed that the devices can be employed for optical communication applications.
A comparison of the electrical characteristics of TiO2/p-Si/Ag, GNR-TiO2/p-Si/Ag and MWCNT-TiO2/p-Si/Ag photodiodes
(Springer, 2019) Erdal, Mehmet Okan; Yildirim, Murat; Kocyigit, Adem
The TiO2/p-Si/Ag, graphene nanoparticles doped (GNR) TiO2/p-Si/Ag and multi-walled carbon nanotube (MWCNT) doped TiO2/p-Si/Ag photodiodes were fabricated by electro-spinning technique at the same experimental conditions, and their structural, morphological and electrical properties were compared for photodiode applications. XRD measurements were confirmed undoped, GNR and MWCNT doped TiO2 structures, and brookite phase of (121) preferred orientation TiO2 has been observed from XRD patterns. SEM images of the heterojunctions showed that undoped and doped TiO2 layer have homogenous surfaces. I-V measurements were performed for electrical characterization of the TiO2/p-Si/Ag, GNR-TiO2/p-Si/Ag and MWCNT-TiO2/p-Si/Ag photodiodes under dark and light illumination conditions at room temperatures. The results imparted that all heterojunctions have good rectifying and photodiode properties. Some heterojunction parameters such as ideality factor, barrier height, series resistance were calculated and discussed in details according to thermionic emission theory, Cheung and Norde techniques. The determined ideality factor values are 8.55, 9.70 and 8.99, and barrier height values are 0.75 eV, 0.74 eV and 0.73 eV for the TiO2/p-Si/Ag, GNR-TiO2/p-Si/Ag and MWCNT-TiO2/p-Si/Ag photodiodes, respectively. These heterojunctions can be considered and improved as photodiodes in industrial applications.
Determination of mechanical properties of polymer matrix composites reinforced with electrospinning N66, PAN, PVA and PVC nanofibers: A comparative study
(Elsevier, 2021) Uslu, Emin; Gavgali, Mehmet; Erdal, Mehmet Okan; Yazman, Sakir; Gemi, Lokman
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/m(3) 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.
Dielectric characterization of Al/PCBM:ZnO/p-Si structures for wide-range frequency
(Indian Acad Sciences, 2021) Yildiz, Dilber Esra; Kocyigit, Adem; Erdal, Mehmet Okan; Yildirim, Murat
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.
Effect of an ITIC non-fullerene interlayer on electrical properties and external quantum efficiency of Al/ZnO/p-Si Schottky photodiodes
(Springer, 2023) Oeztuerk, Teoman; Hussaini, Ali Akbar; Erdal, Mehmet Okan; Durmaz, Fatih; Yildirim, Murat
Metal-semiconductor (MS) heterojunctions are one of the main components of today's technology. In the production of metal-semiconductor heterojunctions; metal oxides, insulators or polymers are inserted as interlayers between metal and semiconductor to ameliorate the durability, stability and efficiency of heterojunctions. By improving their durability, stability and efficiency through the use of ITIC as an interlayer material, the performance of these devices can be enhanced. By adding ITIC to the ZnO interlayer, ITIC: ZnO layer heterojunctions applications were carried out in this study. ITIC, a nonfullerene material, is employed as an electron acceptor material in organic solar cells. The ITIC:ZnO composite layer in our study was grown on Si substrates using spin coating method. Subsequently, Al/ZnO/p-Si and Al/ITIC:ZnO/p-Si heterojunctions were produced by physical vapor deposition method and the electrical properties of the produced devices were characterized. In these characterizations, current-voltage measurements were performed in the dark and under various light power illumination intensities ranging from 20 to 100 mW/cm(2). From the current-voltage characteristics, various electrical parameters were calculated. While the ideality factor values for Al/ZnO/p-Si were found to be 7.55 and 7.73, it was found as 6.83 and 6.65 for ITIC-doped photodiode using thermionic emission and Cheung models, respectively. The barrier height values for Al/ZnO/p-Si were 0.62 eV, 0.64 eV and 0.64 eV, while the same values were found as 0.60 eV, 0.63 eV and 0.61 eV for Al/ITIC:ZnO/p-Si using the thermionic emission, Cheung and Norde models, respectively. From current transient measurements, photosensitivity, specific detectivity and responsivity were calculated as optoelectronic parameters. Moreover, the heterojunctions demonstrated high external quantum efficiency with the addition of ITIC. According to the results, ITIC component is functional for photodiode and photodetector applications.
Effect of Indium Doping on Optical Parameter Properties of Sol-Gel-Derived ZnO Thin Films
(Walter De Gruyter Gmbh, 2019) Kocyigit, Adem; Erdal, Mehmet Okan; Yildirim, Murat
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.
Effect of Indium Doping on Optical Parameter Properties of Sol-Gel-Derived ZnO Thin Films
(Walter De Gruyter Gmbh, 2019) Kocyigit, Adem; Erdal, Mehmet Okan; Yildirim, Murat
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 effect of nanofiber on the biological traits of Drosophila Melanogaster
(2017) Güneş, Eda; Erdal, Mehmet Okan; Gemi, Lokman
Today nanofiber components (polyacrylonitrile dimethyl formamide etc.) are used in many engineeringfields and food industry. Possible effects are need to be identified on the environment and non-targetorganisms. Drosophila melanogaster Meigen (Diptera: Drosophilidae) has been one of the most studiedorganisms, working as a model in developmental biology and environmental studies. In this study, adultswere fed with nanofiber coated diet (PAN-DMF; produced by the electrospinning, range of diamer 260nm), eggs were obtained from adults, and biological traits were observed until the adult stage. The effectof nanofiber on survivorship and development ratio of D. melanogaster were investigated. Nutrient surfaceand viability were visualized by using SEM. According to the obtained results, PAN-DMF is suited withthe nutrient surface compared to controls; and was found to have no adverse effect on the development ofinsect. Nanofibers can be used in food contact organisms, but more detailed studies would be needed tounderstand the effects of these components on environment and non target organisms.
Electrolyte performance of green synthesized carbon quantum dots from fermented tea for high-speed capacitors
(Elsevier Science Sa, 2023) Baslak, Canan; Demirel, Serkan; Kocyigit, Adem; Erdal, Mehmet Okan; Yildirim, Murat
In recent years, obtaining carbon nanomaterials from natural products by natural methods has been among the most popular topics. The materials synthesized by this way have beneficial properties such as biocompatible, photostable and less harmful for environment. In this study, carbon quantum dots (CQDs) were synthesized by using fermented tea as a natural material and carbon source. The capacitor performance as an electrolyte was investigated with high-speed charge-discharge method as unusual in the literature. The characterizations of the CQDs were realized by HRTEM, XRD, XPS, UV-Vis absorption, and fluorescence spectroscopy techniques. The resulting particles have a size of about 10 nm according to HRTEM image. While the structural properties of the CQDs were confirmed by XRD and XPS, and optical behaviors were confirmed by UV-Vis and fluorescence spectroscopies. The electrochemical behavior of the obtained CQDs was tested as electrolyte material for capacitor applications. Experiments were carried out in three different operating potential windows in the 0-2 V range, and CQDs electrolytes exhibited high capacitive effect in symmetrical capacitors. However, the cyclic voltammetry (CV) analyses revealed that the CQDs electrolytes displayed a full supercapacitor electrolyte feature in the 0-0.5 V range. The CQDs electrolytes have a promising material for technological and industrial applications with their unique redox performance and high capacitive effect.
Investigation of electrical conductivity of PAN nanofibers containing silica nanoparticles produced by electrospinning method
(Elsevier, 2019) Mpukuta, Olivier Mukongo; Dincer, Kevser; Erdal, Mehmet Okan
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.
Investigation of Electrical Conductivity of Polyacrylonitrile (PAN) Nanofibers/Nano Particul (Ag, Cu, CNT and GNR)
(Trans Tech Publications Ltd, 2017) Onal, Gurol; Erdal, Mehmet Okan; Dincer, Kevser
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 degrees 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.
Investigation of electrical properties of Al/LiCoO2/n-Si photodiode by ultrasonic spray pyrolysis method
(Springer Heidelberg, 2023) Hussaini, Ali Akbar; Erdal, Mehmet Okan; Doğan, Kemal; Koyuncu, Mustafa; Yıldırım, Murat
here has been rising concentration on the photodiode properties of the MS devices in recent years to improve the perfor mance of light sensing devices. Therefore, in this study, LiCoO2 was synthesized via sol–gel-based electrospinning method and it is used as interlayer between Al and n-type Si to fabricate Al/LiCoO2/n-Si photodiode via ultrasonic spray pyrolysis and physical vapor deposition methods. LiCoO2 thin flm was characterized via XRD, SEM and AFM. Crystallite size for LiCoO2 was found to be 37.75 nm. Electrical characterization was performed by current–voltage (I−V) and current-transient (I−t) measurements using solar simulator under dark and various illumination conditions. I−V characteristics demonstrated that the Al/LiCoO2/n-Si exhibited good photodiode behavior and a high rectifying ratio. Moreover, LiCoO2-interlayered device has shown signifcant responsivity and detectivity. It has shown 1.79× 1010 Jones detectivity and 0.364 A/W responsivity at 100 mW light power. Thus, the results demonstrate that a device based on LiCoO2 can be employed in optoelectronic applications.
Investigation of photosensitive properties of novel TiO2:Cu2O mixed complex interlayered heterojunction: showcasing experimental and DFT calculations
(Springer, 2024) Aksan, Sinem; Hussaini, Ali Akbar; Erdal, Mehmet Okan; Tastan, Oguzhan; Guzel, Rabia; Sacmaci, Serife; Yildirim, Murat
In this study, we investigated the effect of different reducing agents (ascorbic acid and sodium boron hydride) on optoelectronic properties of TiO2:Cu2O nanocomposites. The TiO2:Cu2O nanocomposites were characterized using X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and Energy dispersive X-ray (EDX). The electronic properties of the structure were calculated with the density functional theory (DFT). Both devices showed good responsivity and detectivity against light intensities. The photosensitivity of the devices had linear increasing profile with increasing light power. It is noteworthy that both devices demonstrated well-rectifying behaviors as a result of having low reverse bias and greater forward bias currents at the I-V characteristics in low light. The reduction of the band gap shifted the absorption band gap from the visible light region to the red edge. Density Functional Theory (DFT) calculations which has been done by using CASTEP are in good agreement with our experimental results. Ti(1 - x)CuxO2 (7.5:1) band gap is 1.18 eV which is compared to the Shockley ve Quiser (SQ) limit. Ti(1 - x)CuxO2 (15:1) band gap is 1.83 eV while the band gap is 2.28 eV for stoichiometric TiO2 with our DFT calculations. Thus, the band gap narrowed with increasing Cu amount. This provides an improvement in light absorption. In conclusion, the results demonstrate that Al/TiO2:Cu2O/p-Si can be used in optoelectronic applications.
The modification of the characteristics of ZnO nanofibers by TCNQ doping content
(Springer, 2021) Erdal, Mehmet Okan; Koyuncu, Mustafa; Dogan, Kemal; Ozturk, Teoman; Kocyigit, Adem; Yildirim, Murat
In this study, the electrical properties of an Al/p-Si metal/semiconductor photodiodes with Tetracyanoquinodimethane-Polyvinyl chloride (TCNQ-PVC) and PVC-TCNQ:ZnO interfacial layers were investigated. Growing of the interfacial layers on p-Si were fulfilled using electrospinning method as a fiber form. Al metallic and ohmic contacts were deposited via physical vapor deposition method. Scanning electron microscopy (SEM) pictures of the devices were captured to examine the morphology of the structure. Within the scope of electrical characterization, I-V measurements of the Al/PVC-TCNQ/p-Si and Al/PVC-TCNQ:ZnO/p-Si devices were accomplished both in the dark and under illumination conditions. Various device parameters, such as ideality factor and barrier height values were determined from I-V characteristics. Although the ideality factor values were obtained as 8.47 and 6.85 for undoped and ZnO-doped Al/PVC-TCNQ/p-Si diodes, the barrier height values were calculated as 0.84 for both devices. When a comparison was made between ZnO doped and undoped Al/PVC-TCNQ/p-Si diodes, it was evaluated that the rectification and photoresponse properties of the heterojunction diode was improved with ZnO dopant.
Photodiode behaviors of the AgSbS2 nanocrystals in a Schottky structure
(Iop Publishing Ltd, 2021) Kocyigit, Adem; Erdal, Mehmet Okan; Ozel, Faruk; Yildirim, Murat
Cubic phase AgSbS2 nanocrystals (NCs) were synthesized by the hot-injection method, and they were inserted between the Al and p-Si to fabricate Al/AgSbS2/p-Si photodiode by the thermal evaporation method. AgSbS2 NCs were characterized by XRD, SEM and TEM instruments to confirm the crystal phase, surface morphology as well as crystalline size. The XRD pattern revealed that the cubic crystalline structure of the AgSbS2. The spherical shapes and well surface morphology were affirmed by SEM and TEM analysis. Al/AgSbS2/p-Si photodiode was characterized by I-V measurements depending on the light power intensity and by C-V measurement for various frequencies. I-V characteristics revealed that the Al/AgSbS2/p-Si exhibited good photodiode behavior and a high rectifying ratio. Various diode and detector parameters were extracted from I-V measurements, and they were discussed in detail. The C-V characteristics highlighted that the Al/AgSbS2/p-Si photodiode showed voltage and frequency dependent profile at the accumulation region. The fabricated Al/AgSbS2/p-Si photodiode can be thought for optoelectronic applications.
Photoresponse properties of coronene nanowires thin-film-based photodiode
(Springer, 2020) Erdal, Mehmet Okan
The Al/CRNNW/n-Si device with a coronene nanowire (CRNNW) interlayer was fabricated by a physical vapor deposition technique and characterized under dark various illumination intensities viaI-Vmeasurements at room temperature. The device has exhibited rectifying behavior and the rectifying ratio values decreased from 1.16 x 10(3)to 1.44 at 4 V biases by increasing light intensity from 20 to 100 mW. The Al/CRNNW/n-Si device was characterized by various techniques such as thermionic emission theory, Norde, and Cheung technique, and device parameters were obtained. The ideality factor and barrier height values were determined as 21.33 and 0.75 eV, respectively, under dark condition from the thermionic emission theory. The series resistance of the device is obtained as 3090 ohm from the Norde method and 9840 ohm from the Cheung method for the dark condition. The current transport mechanism of the device was discussed in detail for various regions from lnI-lnVplot. The coronene layer can be thought of and improved as interfacial material for metal-semiconductor devices.
Quasi-Static tensile loading performance of Bonded, Bolted, and hybrid Bonded-Bolted Carbon-to-Carbon composite Joints: Effect of recycled polystyrene nanofiber interleaving
(Elsevier Sci Ltd, 2023) Tinastepe, Mehmet Talha; Kaybal, Halil Burak; Ulus, Hasan; Erdal, Mehmet Okan; Cetin, Mehmet Emin; Avci, Ahmet
Although hybrid bolted/bonded (HBB) joints possess each joint technique's benefits, the adhesive layer performance significantly affects the load-carrying capacity of hybrid joints. Nanofiber interleaving has become an efficient solution to improve the adhesion performance of bonded and HBB joints. This paper reveals the effectiveness of polystyrene (PS) nanofibers interleaving on the mechanical properties of adhesively bonded and HBB single lap joints (SLJs). For this purpose, PS nanofibers are produced via electrospinning from wasted polymers as a nature-friendly implementation. The PS nanofiber mats were interleaved between adherends as a reinforcement layer, and specimens were tested under quasi-static tensile loading. A significant improvement was seen in the peak load value of 10% for the HBB joint, and the fracture energy of the bonded joint increased by 15% with PS nanofiber modification. The failure modes of PS-reinforced specimens developed as more gradually progressive compared to neat specimens thanks to the compatibility of the recycled PS nanofiber with the epoxy and improved adhesive layer performance with PS modification. Furthermore, the morphological analyses of post-fracture specimens were monitored to realize the damage and nano-toughness mechanisms.
Temperature dependent current-voltage characteristics of Al/TiO2/n-Si and Al/Cu:TiO2/n-Si devices
(Elsevier Sci Ltd, 2019) Erdal, Mehmet Okan; Kocyigit, Adem; Yildirim, Murat
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.
Thermoelectric Properties of Nickel and Boron Co-Substituted NaCo2O4 Prepared by Electrospinning Technique
(Trans Tech Publications Ltd, 2018) Erdal, Mehmet Okan; Koyuncu, Mustafa; Aksu, M. Levent; Uslu, Ibrahim; Kocyigit, Serhat
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 Xray 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 x 10(-5), 5.3 x 10(-6), 8.6 x 10(-5) and 9 x 10(-6) for sintered powders from undoped, Ni and B doped powders, respectively.

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