Arda Aytimur | Bilecik University (original) (raw)

Papers by Arda Aytimur

Ceramics International, 2015

Graphene oxide-doped praseodymium barium cobalt oxide (GO-doped PrBaCoO) nanoceramic was used an ... more Graphene oxide-doped praseodymium barium cobalt oxide (GO-doped PrBaCoO) nanoceramic was used an interfacial layer for the purpose of increasing the capacitance in Au/n-Si metal–semiconductor (MS) structures. The frequency and voltage dependence of dielectric constant (ε′), dielectric loss (ε″), loss tangent (tan δ), the real and imaginary parts of electric modulus (M′ and M″) and ac electrical conductivity (σac) of Au/GO-doped PrBaCoO nanoceramic/n-Si capacitors were investigated in detail by impedance spectroscopy method in the wide frequency range of 1 kHz to 1 MHz at room temperature. Experimental results showed that ε′–V plot has two distinct peaks that are located at about 0 and 2 V, respectively, at low frequencies, but the first peak disappears at high frequencies. While the value of M′ increase with increasing frequency M″ shows a peak and the peak position shifts to higher frequency with increasing applied voltage. Such peak behavior can be attributed to the particular distribution of interface states located between Au and interfacial layer and to the interfacial polarization. It can be concluded that the interfacial polarization and the charges at interface can easily follow ac signal at low frequencies. In addition, the ln(σac) vs ln(ω) plot of the capacitor for 3 V has two linear regions (I and II) with different slopes which correspond to low and high frequency ranges, respectively. Such behavior of ln(σac) vs ln(ω) plot indicated that there are two different conduction mechanisms in the Au/GO-doped PrBaCoO nanoceramic/n-Si capacitor at room temperature.

Journal of Inorganic and …

In this study, boron doped and undoped poly (vinyl) alcohol/bismuth–gadolina acetate (PVA/Bi–Gd) ... more In this study, boron doped and undoped poly (vinyl) alcohol/bismuth–gadolina acetate (PVA/Bi–Gd) nanofibers were prepared using electrospinning technique then calcinated at 800 °C for 2 h.
The originality of this study is the addition of boron to metal acetates. The effects of boron doping were investigated in terms of solution properties, morphological changes and thermal characteristics.
The characteristics of the fibers were investigated with FT-IR, XRD, SEM and BET. The addition of boron did not only increase the thermal stability of the fibers, but also their diameters, which yielded stronger fibers. XRD analyses showed that boron doping increased the peak intensities and indicated that the boron doping enhanced the crystallite size. Moreover, no shifts were noticed in diffraction angles for boron doped and undoped samples. Therefore, boron doping did not significantly alter the lattice spacing. The SEM micrograph of the fibers showed that the addition of boron resulted in the formation of cross-linked bright-surfaced fibers. The average fiber diameter for boron doped and undoped fiber mats were 204 and 123 nm, respectively. Also, grain diameters of boron doped and undoped nanocrystalline sintered powders were measured as 140 and 118 nm, respectively. The BET results showed that boron undoped and doped Bi2O3–La2O3 nanocrystalline powder ceramic structures sintered at 800 °C have surface areas of 59.72 and 39.80 m2/g, respectively.

In this study, PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fiber mats were prepa... more In this study, PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fiber mats were prepared via electrospinning.
Synthesized nanofibers were characterized by DSC, FT-IR and SEM. DSC results showed that the nanofibers were degraded at 400
C and 450
C. The addition of PVP-K30, PVP-I and chitosan to PVA/PAA structure increased the thermal stability
of the nanofibers. SEM micrographs showed that synthesized nanofibers are linear. Fiber diameter measurements showed that average diameters of the fibers are less than 0.5 micron. The average diameters of PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fibers were calculated as 458 nm, 237 nm, 139 nm, and 270 nm, respectively.

Ceramics İnternational, Sep 2014

Boron doped and undoped Bi 2 O 3 –Y 2 O 3 nanofibers were synthesized by the electrospinning meth... more Boron doped and undoped Bi 2 O 3 –Y 2 O 3 nanofibers were synthesized by the electrospinning method. The nanofibers were then calcined to obtain nanocrystalline ceramics. The synthesized nanofibers and nanocrystalline ceramics were characterized using XRD, FT-IR, SEM and XPS. According to the XRD results the undoped Bi 2 O 3 –Y 2 O 3 nanocrystalline ceramic has a face-centered cubic structure. The XPS results show that nanocrystalline ceramics were pure Bi 2 O 3 , and there were no peaks related to either bivalent or tetravalent or pentavalent states in Bi 2 O 3. The XPS results also show that the crystallinity of the boron doped nanocrystalline ceramic was decreased because of the network former property of the boron. The average fiber diameters for electrospun boron doped and undoped PVA/Bi–Y acetate nanofibers were calculated as 179 nm and 96 nm, respectively. The SEM micrographs of the nanocrystalline ceramics show that the undoped Bi 2 O 3 –Y 2 O 3 ceramic has needle-like crystalline structure. However, the crystallinity of the boron doped Bi 2 O 3 –Y 2 O 3 ceramic decreased because of boron doping.

In this study, the boron-doped barium-stabilized bismuth cobalt oxide thermoelectric nanocrystall... more In this study, the boron-doped barium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powders were produced by the polymeric precursor technique. The powders were characterized by X-ray diffraction, scanning electron microscopy, and the physical properties measurement system. The X-ray diffraction results showed that these patterns
have mixture of two phases as face-centered cubic and body-centered cubic. Values of the crystallite size, the dislocation density, and the microstrain were calculated by the Scherrer
equation. According to these values, the crystallite size decreased from 60 to 51 nm with the boron addition in the boron-undoped and boron-doped samples, respectively. The scanning electron microscope results showed that nanograins are rarely seen in the boron-undoped samples, but nanograins turn into needle-like and layered structures with boron addition. The diameters distribution of nanofibers was calculated. The average diameter of the boron-doped sample is smaller than the boron-undoped sample. The physical properties measurement system values showed that the electrical and thermal conductivity, the Seebeck coefficient, and the figure of merit increased with the temperature rise for both samples. The boron-doping effect increased the electrical and thermal conductivity, decreased the Seebeck coefficient, and decreased the figure of merit.

In this study, boron doped and undoped Bi2O3-Er2O3 nanocomposite fibers were produced via electro... more In this study, boron doped and undoped Bi2O3-Er2O3 nanocomposite fibers were produced via electrospinning technique. Obtained fibers were turned into ceramics via calcination process. Obtained nanocomposite fibers and ceramics were characterized by Fourier transform infrared, x-ray diffraction, and scanning electron microscopy techniques. X-ray diffraction results show that boron undoped Bi2O3-Er2O3 ceramic consisted of face-centered cubic Bi2O3-Er2O3 phase. However, boron doped Bi2O3-Er2O3 ceramic consisted of orthorhombic phase. Crystallite sizes of the ceramics were evaluated using Scherrer's equation. Crystallite sizes of boron doped and undoped ceramics were calculated as 50 and 17 nm, respectively. The average fiber diameters for boron doped and undoped poly vinyl alcohol/Bi-Er acetate nanofibers were calculated as 79 nm and 96 nm, respectively. The Brunauer Emmett teller results show that boron undoped and doped Bi2O3-Er2O3 nanocrystalline powder ceramic structures sintered at 800 have surface area of 20.44 and 12.93 m2/g, respectively.

Calcia-stabilized cerium doped cubic zirconia nanocrystalline ceramic was synthesized using poly ... more Calcia-stabilized cerium doped cubic zirconia nanocrystalline ceramic was synthesized using poly (vinyl alcohol) as a polymeric precursor. Obtained ceramic was pressed into a cylindrical pellet and sintered at 850 °C. The calcined and sintered ceramics were characterized by XRF, XRD, BET and SEM. The XRD pattern of the calcined ceramic shows that the ceramic has a face centered cubic crystal structure. The SEM results show that the grain size of the ceramic was increased after sintering. The BET surface areas were determined as 13.236 and 4.397 m2 g−1 for the calcined and sintered ceramics, respectively.

Biocompatible polyvinyl alcohol=polyethylene glycol and polyvinyl alcohol=polypropylene glycol co... more Biocompatible polyvinyl alcohol=polyethylene glycol and polyvinyl alcohol=polypropylene glycol copolymer mats were prepared by
electrospinning. The composite fiber mats were subjected to detailed physical analysis complemented by scanning electron microscopy
and Fourier transformations infrared spectroscopy. Scanning electron microscopy images showed that the morphology and diameters
of the fibers were mainly affected by the types of polymers and their copolymer compositions. Microbial culture results showed
that among the tested fibrous mats polyvinyl alcohol=50% polyethylene glycol gave the best results in preventing the cell attachment
and proliferation. This novel electrospun matrix would be used as potential wound dressing material for skin regeneration.

Polymer-Plastics Technology and Engineering, 2014

In this study, PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fiber mats were prepa... more In this study, PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fiber mats were prepared via electrospinning. Synthesized nanofibers were characterized by DSC, FT-IR and SEM. DSC results showed that the nanofibers were degraded at 400°C and 450°C. The addition of PVP-K30, PVP-I and chitosan to PVA/PAA structure increased the thermal stability of the nanofibers. SEM micrographs showed that synthesized nanofibers are linear. Fiber diameter measurements showed that average diameters of the fibers are less than 0.5 micron. The average diameters of PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fibers were calculated as 458 nm, 237 nm, 139 nm, and 270 nm, respectively.

Metallurgical and Materials Transactions A, Aug 2014

In this study, the boron-doped barium-stabilized bismuth cobalt oxide thermoelectric nanocrystall... more In this study, the boron-doped barium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powders were produced by the polymeric precursor technique. The powders were characterized by X-ray diffraction, scanning electron microscopy, and the physical properties measurement system. The X-ray diffraction results showed that these patterns have mixture of two phases as face-centered cubic and body-centered cubic. Values of the crystallite size, the dislocation density, and the microstrain were calculated by the Scherrer equation. According to these values, the crystallite size decreased from 60 to 51 nm with the boron addition in the boron-undoped and boron-doped samples, respectively. The scanning electron microscope results showed that nanograins are rarely seen in the boron-undoped samples, but nanograins turn into needle-like and layered structures with boron addition. The diameters distribution of nanofibers was calculated. The average diameter of the boron-doped sample is smaller than the boron-undoped sample. The physical properties measurement system values showed that the electrical and thermal conductivity, the Seebeck coefficient, and the figure of merit increased with the temperature rise for both samples. The boron-doping effect increased the electrical and thermal conductivity, decreased the Seebeck coefficient, and decreased the figure of merit.

Journal of Sol-Gel Science and Technology, Apr 2014

The study performs preparation of the precursor thin films with MgO doped ZnO nanocrystalline cer... more The study performs preparation of the precursor thin films with MgO doped ZnO nanocrystalline ceramics by electrospinning technique and their characterizations by small and wide angle X-ray scattering methods. The prepared films on Si and commercial glass wafers as nanoceramic mats were calcined at 320, 340, 360 and 380 °C. The role of the annealing conditions on the morphological changes and uniformity of the films was also investigated. Results show that, the thermal process and choice of the wafer are critical for film morphology at the nano and atomic scales through the network shrinkage and crystallization, respectively. Samples show mono/poly disperse isolated nanoclusters/regular lamellar distributions/and embedded aggregations.

POLYMER-PLASTICS TECHNOLOGY AND ENGINEERING, May 28, 2013

This study focuses on the fabrication of poly(vinyl alcohol)/ poly(vinyl pyrrolidone)-Iodine nano... more This study focuses on the fabrication of poly(vinyl alcohol)/ poly(vinyl pyrrolidone)-Iodine nanofibers via electrospinning. Electrospun fibers were characterized by FT-IR, DSC and SEM techniques. DSC results indicated that the thermal stability of nanofibers were improved after the addition of chitosan and poloxamer 188. SEM images showed that the spongiform structure is much more compact and fibrous in the case of added chitosan, with an average fiber diameter of 374nm, whereas the addition of poloxamer 188 resulted in a more porous and beaded composition, with average fiber diameter of 489nm.

ADVANCES IN APPLIED CERAMICS, Aug 2013

In this paper, the fabrication and characterisation processes of both boron doped and undoped bar... more In this paper, the fabrication and characterisation processes of both boron doped and undoped barium stabilised bismuth cobalt oxide nanocrystalline ceramic powders using polymeric precursor were reported. Obtained boron doped barium stabilised bismuth cobalt oxide nanocrystalline ceramic powders, which have been synthesised by polymeric precursor technique at temperatures below 900 degrees C and at atmospheric condition, were characterised by X-ray diffraction, Fourier transform infrared and scanning electron microscopy techniques. According to X-ray results, fcc and bcc phases coexist in the samples of the nanocrystalline ceramic powders. Crystallite sizes for body centred cubic structure were calculated using Scherrer equation for both boron doped and undoped samples. In addition, lattice parameters were calculated for all samples.

CURRENT NANOSCIENCE, Aug 2013

PVA/PAA/PEG/PVP nanofibers with HPMC and aloe vera were fabricated by electrospinning method. HPM... more PVA/PAA/PEG/PVP nanofibers with HPMC and aloe vera were fabricated by electrospinning method. HPMC was added to the hybrid polymer solution as the water retention agent and aloe vera which are known over centuries were also added to the system to promote the healing of wounded or infected skin. The fabricated nanofiber mats were characterized using SEM, DSC, and FT-IR. SEM Images exhibited that the electrospun nanofibers were homogenous and linear. The nanofiber diameters ranged between 80-480 nm.

POLYMER-PLASTICS TECHNOLOGY AND ENGINEERING, Sep 26, 2013

The PVA/PVP, PVA/PVP with 5% and 10% chitosan and PVA/PVP-Iodine fibers were produced via electro... more The PVA/PVP, PVA/PVP with 5% and 10% chitosan and PVA/PVP-Iodine fibers were produced via electrospinning technique. Their morphological and chemical characteristics were examined with SEM, TGA, FT-IR, viscometer and four-point probe conductivity measurement apparatus. The addition of chitosan increased the viscosity and the electrical conductivity of the polymer. The increase chitosan contents resulted in the diameters of the fibers smaller than expected. This was attributed to the increase in the viscosity of the solution and the electrical conductivity of the resulting fibers. The DSC results show that iodine was efficiently cross-linked with the polymer, forming an amorphous structure.

JOM, Jan 2014

Boron-doped strontium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powd... more Boron-doped strontium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powders were produced by using a polymeric precursor technique. The powders were characterized by using x-ray diffraction (XRD), scanning electron microscopy (SEM), and physical properties measurement system (PPMS) techniques. The XRD results showed that these patterns have a two-phase mixture. The phases are face-centered cubic (fcc) and body-centered cubic (bcc). Values of the crystallite size, dislocation density, and microstrain were calculated by using the Scherrer equation. The lattice parameters were calculated for fcc and bcc phases. The SEM results showed that needle-like grains are formed in boron-undoped composite materials, but the needle-like grains changed to the plate-like grains with the addition of boron. The distribution of the nanofiber diameters was calculated and the average diameter of the boron-doped sample is smaller than the boron-undoped one. PPMS values showed that the electrical resistivity values decreased, but the thermal conductivity values, the Seebeck coefficients, and figure of merit (ZT) increased with increasing temperature for the two samples.

Ceramics International, Mar 21, 2013

The synthesis of boron undoped and doped indium stabilized bismuth oxide nanoceramic powders via ... more The synthesis of boron undoped and doped indium stabilized bismuth oxide nanoceramic powders via the polymeric precursor technique were described. The physical properties of the precursor polymer solutions (pH, surface tension, viscosity and conductivity) were measured.

The morphological and structural characteristics of the nanoceramic powders were investigated by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier transform infrared spectroscopy ( FTIR).

The lattice constant, average particle size, microstrain and dislocation density of the samples were calculated. The results show that the average particle size decreased while both the microstrain and the dislocation density values increased in the boron doped indium stabilized bismuth oxide. The structure proposed from FTIR spectra is mainly based on BiO6 and BiO3 units.

Journal of Sol-Gel Science and Technology, 2013

In this study, erbia (Er2O3)-doped Bi2O3 ceramics were prepared from sol–gel derived nanocrystall... more In this study, erbia (Er2O3)-doped Bi2O3 ceramics were prepared from sol–gel derived nanocrystalline powders. The morphological properties were investigated by scanning electron microscopy. X-ray diffraction (XRD) analysis was carried out in order to characterize the phase and crystal structure of the powder samples. Temperature dependent electrical properties were determined by thermogravimetry/differential thermal analyzer (TG/DTA) and 4-point probe techniques. The stable fluorite face centered cubic δ-type phase was observed at room temperature from the XRD result, which was supported by the DTA and temperature dependent electrical conductivity measurements. Electrical conductivity results indicate that there is a transition approximately at 650 °C, which can be attributed to an order–disorder transition (ODT). The activation energy values obtained from the Arrhenius approach for heating and cooling process were presented. Two regimes, corresponding to high temperature region (HTR) and low temperature region (LTR), were observed. As a result of morphological changes during the ODT, the electrical conductivity modifies and the activation energies are different for studied sample at HTR and LTR.

Abstract Er 2 O 3 doped calcia stabilized zirconia based inert matrix fuel containing CeO 2 as a ... more Abstract Er 2 O 3 doped calcia stabilized zirconia based inert matrix fuel containing CeO 2 as a surrogate for PuO 2 was fabricated for a wide range of concentration using the polymer-to-ceramic conversion technique via metal acetate preceramic hybrid polymer solutions. Samples were characterized by XRD, SEM and AFM techniques. Nanocrystallite size variation in the samples was evaluated using peak broadening values by means of the Scherrer formula.

Ceramics International, 2015

Graphene oxide-doped praseodymium barium cobalt oxide (GO-doped PrBaCoO) nanoceramic was used an ... more Graphene oxide-doped praseodymium barium cobalt oxide (GO-doped PrBaCoO) nanoceramic was used an interfacial layer for the purpose of increasing the capacitance in Au/n-Si metal–semiconductor (MS) structures. The frequency and voltage dependence of dielectric constant (ε′), dielectric loss (ε″), loss tangent (tan δ), the real and imaginary parts of electric modulus (M′ and M″) and ac electrical conductivity (σac) of Au/GO-doped PrBaCoO nanoceramic/n-Si capacitors were investigated in detail by impedance spectroscopy method in the wide frequency range of 1 kHz to 1 MHz at room temperature. Experimental results showed that ε′–V plot has two distinct peaks that are located at about 0 and 2 V, respectively, at low frequencies, but the first peak disappears at high frequencies. While the value of M′ increase with increasing frequency M″ shows a peak and the peak position shifts to higher frequency with increasing applied voltage. Such peak behavior can be attributed to the particular distribution of interface states located between Au and interfacial layer and to the interfacial polarization. It can be concluded that the interfacial polarization and the charges at interface can easily follow ac signal at low frequencies. In addition, the ln(σac) vs ln(ω) plot of the capacitor for 3 V has two linear regions (I and II) with different slopes which correspond to low and high frequency ranges, respectively. Such behavior of ln(σac) vs ln(ω) plot indicated that there are two different conduction mechanisms in the Au/GO-doped PrBaCoO nanoceramic/n-Si capacitor at room temperature.

Journal of Inorganic and …

In this study, boron doped and undoped poly (vinyl) alcohol/bismuth–gadolina acetate (PVA/Bi–Gd) ... more In this study, boron doped and undoped poly (vinyl) alcohol/bismuth–gadolina acetate (PVA/Bi–Gd) nanofibers were prepared using electrospinning technique then calcinated at 800 °C for 2 h.
The originality of this study is the addition of boron to metal acetates. The effects of boron doping were investigated in terms of solution properties, morphological changes and thermal characteristics.
The characteristics of the fibers were investigated with FT-IR, XRD, SEM and BET. The addition of boron did not only increase the thermal stability of the fibers, but also their diameters, which yielded stronger fibers. XRD analyses showed that boron doping increased the peak intensities and indicated that the boron doping enhanced the crystallite size. Moreover, no shifts were noticed in diffraction angles for boron doped and undoped samples. Therefore, boron doping did not significantly alter the lattice spacing. The SEM micrograph of the fibers showed that the addition of boron resulted in the formation of cross-linked bright-surfaced fibers. The average fiber diameter for boron doped and undoped fiber mats were 204 and 123 nm, respectively. Also, grain diameters of boron doped and undoped nanocrystalline sintered powders were measured as 140 and 118 nm, respectively. The BET results showed that boron undoped and doped Bi2O3–La2O3 nanocrystalline powder ceramic structures sintered at 800 °C have surface areas of 59.72 and 39.80 m2/g, respectively.

In this study, PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fiber mats were prepa... more In this study, PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fiber mats were prepared via electrospinning.
Synthesized nanofibers were characterized by DSC, FT-IR and SEM. DSC results showed that the nanofibers were degraded at 400
C and 450
C. The addition of PVP-K30, PVP-I and chitosan to PVA/PAA structure increased the thermal stability
of the nanofibers. SEM micrographs showed that synthesized nanofibers are linear. Fiber diameter measurements showed that average diameters of the fibers are less than 0.5 micron. The average diameters of PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fibers were calculated as 458 nm, 237 nm, 139 nm, and 270 nm, respectively.

Ceramics İnternational, Sep 2014

Boron doped and undoped Bi 2 O 3 –Y 2 O 3 nanofibers were synthesized by the electrospinning meth... more Boron doped and undoped Bi 2 O 3 –Y 2 O 3 nanofibers were synthesized by the electrospinning method. The nanofibers were then calcined to obtain nanocrystalline ceramics. The synthesized nanofibers and nanocrystalline ceramics were characterized using XRD, FT-IR, SEM and XPS. According to the XRD results the undoped Bi 2 O 3 –Y 2 O 3 nanocrystalline ceramic has a face-centered cubic structure. The XPS results show that nanocrystalline ceramics were pure Bi 2 O 3 , and there were no peaks related to either bivalent or tetravalent or pentavalent states in Bi 2 O 3. The XPS results also show that the crystallinity of the boron doped nanocrystalline ceramic was decreased because of the network former property of the boron. The average fiber diameters for electrospun boron doped and undoped PVA/Bi–Y acetate nanofibers were calculated as 179 nm and 96 nm, respectively. The SEM micrographs of the nanocrystalline ceramics show that the undoped Bi 2 O 3 –Y 2 O 3 ceramic has needle-like crystalline structure. However, the crystallinity of the boron doped Bi 2 O 3 –Y 2 O 3 ceramic decreased because of boron doping.

In this study, the boron-doped barium-stabilized bismuth cobalt oxide thermoelectric nanocrystall... more In this study, the boron-doped barium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powders were produced by the polymeric precursor technique. The powders were characterized by X-ray diffraction, scanning electron microscopy, and the physical properties measurement system. The X-ray diffraction results showed that these patterns
have mixture of two phases as face-centered cubic and body-centered cubic. Values of the crystallite size, the dislocation density, and the microstrain were calculated by the Scherrer
equation. According to these values, the crystallite size decreased from 60 to 51 nm with the boron addition in the boron-undoped and boron-doped samples, respectively. The scanning electron microscope results showed that nanograins are rarely seen in the boron-undoped samples, but nanograins turn into needle-like and layered structures with boron addition. The diameters distribution of nanofibers was calculated. The average diameter of the boron-doped sample is smaller than the boron-undoped sample. The physical properties measurement system values showed that the electrical and thermal conductivity, the Seebeck coefficient, and the figure of merit increased with the temperature rise for both samples. The boron-doping effect increased the electrical and thermal conductivity, decreased the Seebeck coefficient, and decreased the figure of merit.

In this study, boron doped and undoped Bi2O3-Er2O3 nanocomposite fibers were produced via electro... more In this study, boron doped and undoped Bi2O3-Er2O3 nanocomposite fibers were produced via electrospinning technique. Obtained fibers were turned into ceramics via calcination process. Obtained nanocomposite fibers and ceramics were characterized by Fourier transform infrared, x-ray diffraction, and scanning electron microscopy techniques. X-ray diffraction results show that boron undoped Bi2O3-Er2O3 ceramic consisted of face-centered cubic Bi2O3-Er2O3 phase. However, boron doped Bi2O3-Er2O3 ceramic consisted of orthorhombic phase. Crystallite sizes of the ceramics were evaluated using Scherrer's equation. Crystallite sizes of boron doped and undoped ceramics were calculated as 50 and 17 nm, respectively. The average fiber diameters for boron doped and undoped poly vinyl alcohol/Bi-Er acetate nanofibers were calculated as 79 nm and 96 nm, respectively. The Brunauer Emmett teller results show that boron undoped and doped Bi2O3-Er2O3 nanocrystalline powder ceramic structures sintered at 800 have surface area of 20.44 and 12.93 m2/g, respectively.

Calcia-stabilized cerium doped cubic zirconia nanocrystalline ceramic was synthesized using poly ... more Calcia-stabilized cerium doped cubic zirconia nanocrystalline ceramic was synthesized using poly (vinyl alcohol) as a polymeric precursor. Obtained ceramic was pressed into a cylindrical pellet and sintered at 850 °C. The calcined and sintered ceramics were characterized by XRF, XRD, BET and SEM. The XRD pattern of the calcined ceramic shows that the ceramic has a face centered cubic crystal structure. The SEM results show that the grain size of the ceramic was increased after sintering. The BET surface areas were determined as 13.236 and 4.397 m2 g−1 for the calcined and sintered ceramics, respectively.

Biocompatible polyvinyl alcohol=polyethylene glycol and polyvinyl alcohol=polypropylene glycol co... more Biocompatible polyvinyl alcohol=polyethylene glycol and polyvinyl alcohol=polypropylene glycol copolymer mats were prepared by
electrospinning. The composite fiber mats were subjected to detailed physical analysis complemented by scanning electron microscopy
and Fourier transformations infrared spectroscopy. Scanning electron microscopy images showed that the morphology and diameters
of the fibers were mainly affected by the types of polymers and their copolymer compositions. Microbial culture results showed
that among the tested fibrous mats polyvinyl alcohol=50% polyethylene glycol gave the best results in preventing the cell attachment
and proliferation. This novel electrospun matrix would be used as potential wound dressing material for skin regeneration.

Polymer-Plastics Technology and Engineering, 2014

In this study, PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fiber mats were prepa... more In this study, PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fiber mats were prepared via electrospinning. Synthesized nanofibers were characterized by DSC, FT-IR and SEM. DSC results showed that the nanofibers were degraded at 400°C and 450°C. The addition of PVP-K30, PVP-I and chitosan to PVA/PAA structure increased the thermal stability of the nanofibers. SEM micrographs showed that synthesized nanofibers are linear. Fiber diameter measurements showed that average diameters of the fibers are less than 0.5 micron. The average diameters of PVA/PAA, PVA/PAA/PVP, PVA/PAA/PVP-I and PVA/PAA/PVP/Chitosan fibers were calculated as 458 nm, 237 nm, 139 nm, and 270 nm, respectively.

Metallurgical and Materials Transactions A, Aug 2014

In this study, the boron-doped barium-stabilized bismuth cobalt oxide thermoelectric nanocrystall... more In this study, the boron-doped barium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powders were produced by the polymeric precursor technique. The powders were characterized by X-ray diffraction, scanning electron microscopy, and the physical properties measurement system. The X-ray diffraction results showed that these patterns have mixture of two phases as face-centered cubic and body-centered cubic. Values of the crystallite size, the dislocation density, and the microstrain were calculated by the Scherrer equation. According to these values, the crystallite size decreased from 60 to 51 nm with the boron addition in the boron-undoped and boron-doped samples, respectively. The scanning electron microscope results showed that nanograins are rarely seen in the boron-undoped samples, but nanograins turn into needle-like and layered structures with boron addition. The diameters distribution of nanofibers was calculated. The average diameter of the boron-doped sample is smaller than the boron-undoped sample. The physical properties measurement system values showed that the electrical and thermal conductivity, the Seebeck coefficient, and the figure of merit increased with the temperature rise for both samples. The boron-doping effect increased the electrical and thermal conductivity, decreased the Seebeck coefficient, and decreased the figure of merit.

Journal of Sol-Gel Science and Technology, Apr 2014

The study performs preparation of the precursor thin films with MgO doped ZnO nanocrystalline cer... more The study performs preparation of the precursor thin films with MgO doped ZnO nanocrystalline ceramics by electrospinning technique and their characterizations by small and wide angle X-ray scattering methods. The prepared films on Si and commercial glass wafers as nanoceramic mats were calcined at 320, 340, 360 and 380 °C. The role of the annealing conditions on the morphological changes and uniformity of the films was also investigated. Results show that, the thermal process and choice of the wafer are critical for film morphology at the nano and atomic scales through the network shrinkage and crystallization, respectively. Samples show mono/poly disperse isolated nanoclusters/regular lamellar distributions/and embedded aggregations.

POLYMER-PLASTICS TECHNOLOGY AND ENGINEERING, May 28, 2013

This study focuses on the fabrication of poly(vinyl alcohol)/ poly(vinyl pyrrolidone)-Iodine nano... more This study focuses on the fabrication of poly(vinyl alcohol)/ poly(vinyl pyrrolidone)-Iodine nanofibers via electrospinning. Electrospun fibers were characterized by FT-IR, DSC and SEM techniques. DSC results indicated that the thermal stability of nanofibers were improved after the addition of chitosan and poloxamer 188. SEM images showed that the spongiform structure is much more compact and fibrous in the case of added chitosan, with an average fiber diameter of 374nm, whereas the addition of poloxamer 188 resulted in a more porous and beaded composition, with average fiber diameter of 489nm.

ADVANCES IN APPLIED CERAMICS, Aug 2013

In this paper, the fabrication and characterisation processes of both boron doped and undoped bar... more In this paper, the fabrication and characterisation processes of both boron doped and undoped barium stabilised bismuth cobalt oxide nanocrystalline ceramic powders using polymeric precursor were reported. Obtained boron doped barium stabilised bismuth cobalt oxide nanocrystalline ceramic powders, which have been synthesised by polymeric precursor technique at temperatures below 900 degrees C and at atmospheric condition, were characterised by X-ray diffraction, Fourier transform infrared and scanning electron microscopy techniques. According to X-ray results, fcc and bcc phases coexist in the samples of the nanocrystalline ceramic powders. Crystallite sizes for body centred cubic structure were calculated using Scherrer equation for both boron doped and undoped samples. In addition, lattice parameters were calculated for all samples.

CURRENT NANOSCIENCE, Aug 2013

PVA/PAA/PEG/PVP nanofibers with HPMC and aloe vera were fabricated by electrospinning method. HPM... more PVA/PAA/PEG/PVP nanofibers with HPMC and aloe vera were fabricated by electrospinning method. HPMC was added to the hybrid polymer solution as the water retention agent and aloe vera which are known over centuries were also added to the system to promote the healing of wounded or infected skin. The fabricated nanofiber mats were characterized using SEM, DSC, and FT-IR. SEM Images exhibited that the electrospun nanofibers were homogenous and linear. The nanofiber diameters ranged between 80-480 nm.

POLYMER-PLASTICS TECHNOLOGY AND ENGINEERING, Sep 26, 2013

The PVA/PVP, PVA/PVP with 5% and 10% chitosan and PVA/PVP-Iodine fibers were produced via electro... more The PVA/PVP, PVA/PVP with 5% and 10% chitosan and PVA/PVP-Iodine fibers were produced via electrospinning technique. Their morphological and chemical characteristics were examined with SEM, TGA, FT-IR, viscometer and four-point probe conductivity measurement apparatus. The addition of chitosan increased the viscosity and the electrical conductivity of the polymer. The increase chitosan contents resulted in the diameters of the fibers smaller than expected. This was attributed to the increase in the viscosity of the solution and the electrical conductivity of the resulting fibers. The DSC results show that iodine was efficiently cross-linked with the polymer, forming an amorphous structure.

JOM, Jan 2014

Boron-doped strontium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powd... more Boron-doped strontium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powders were produced by using a polymeric precursor technique. The powders were characterized by using x-ray diffraction (XRD), scanning electron microscopy (SEM), and physical properties measurement system (PPMS) techniques. The XRD results showed that these patterns have a two-phase mixture. The phases are face-centered cubic (fcc) and body-centered cubic (bcc). Values of the crystallite size, dislocation density, and microstrain were calculated by using the Scherrer equation. The lattice parameters were calculated for fcc and bcc phases. The SEM results showed that needle-like grains are formed in boron-undoped composite materials, but the needle-like grains changed to the plate-like grains with the addition of boron. The distribution of the nanofiber diameters was calculated and the average diameter of the boron-doped sample is smaller than the boron-undoped one. PPMS values showed that the electrical resistivity values decreased, but the thermal conductivity values, the Seebeck coefficients, and figure of merit (ZT) increased with increasing temperature for the two samples.

Ceramics International, Mar 21, 2013

The synthesis of boron undoped and doped indium stabilized bismuth oxide nanoceramic powders via ... more The synthesis of boron undoped and doped indium stabilized bismuth oxide nanoceramic powders via the polymeric precursor technique were described. The physical properties of the precursor polymer solutions (pH, surface tension, viscosity and conductivity) were measured.

The morphological and structural characteristics of the nanoceramic powders were investigated by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier transform infrared spectroscopy ( FTIR).

The lattice constant, average particle size, microstrain and dislocation density of the samples were calculated. The results show that the average particle size decreased while both the microstrain and the dislocation density values increased in the boron doped indium stabilized bismuth oxide. The structure proposed from FTIR spectra is mainly based on BiO6 and BiO3 units.

Journal of Sol-Gel Science and Technology, 2013

In this study, erbia (Er2O3)-doped Bi2O3 ceramics were prepared from sol–gel derived nanocrystall... more In this study, erbia (Er2O3)-doped Bi2O3 ceramics were prepared from sol–gel derived nanocrystalline powders. The morphological properties were investigated by scanning electron microscopy. X-ray diffraction (XRD) analysis was carried out in order to characterize the phase and crystal structure of the powder samples. Temperature dependent electrical properties were determined by thermogravimetry/differential thermal analyzer (TG/DTA) and 4-point probe techniques. The stable fluorite face centered cubic δ-type phase was observed at room temperature from the XRD result, which was supported by the DTA and temperature dependent electrical conductivity measurements. Electrical conductivity results indicate that there is a transition approximately at 650 °C, which can be attributed to an order–disorder transition (ODT). The activation energy values obtained from the Arrhenius approach for heating and cooling process were presented. Two regimes, corresponding to high temperature region (HTR) and low temperature region (LTR), were observed. As a result of morphological changes during the ODT, the electrical conductivity modifies and the activation energies are different for studied sample at HTR and LTR.

Abstract Er 2 O 3 doped calcia stabilized zirconia based inert matrix fuel containing CeO 2 as a ... more Abstract Er 2 O 3 doped calcia stabilized zirconia based inert matrix fuel containing CeO 2 as a surrogate for PuO 2 was fabricated for a wide range of concentration using the polymer-to-ceramic conversion technique via metal acetate preceramic hybrid polymer solutions. Samples were characterized by XRD, SEM and AFM techniques. Nanocrystallite size variation in the samples was evaluated using peak broadening values by means of the Scherrer formula.

"This innovation is related to the production of nano crystalline preferably pelleted This innova... more "This innovation is related to the production of nano crystalline preferably pelleted This innovation related the coverage of preferably pelleted uranium dioxide nuclear fuel containing various amount of combustible poison such as gadolinium oxide with boron nitride.
It enables the coverage of advanced nuclear fuels with boron nitride with the use of ammonia and boron tribromide.
stabilized preferably boron doped bismuth oxide solid oxide fuel cell ceramic material with the use of a polymer solution and electrospinning technique. The bismuth source is preferably bismuth acetate or bismuth nitrate if desired and lanthanum source is preferably lanthanum acetate or lanthanum nitrate if desired.
This patent involves the addition of boron in order to obtain the ceramic material at lower temperature with the density close to the theoretical value preferably using boric acid as the boron source. This will enable us to obtain high quality hard ceramic composite material resistant against chemical, erosion and elevated temperatures.
The polymer material to be electrospun are the single or the hybrid or the combined uses of glycol (PEG), polyethylene oxide (PEO), polyvinyl acetate (PVAc), polyvinyl pyrolydine (PVP) and/or polyvinyl alcohol (PVA).
The resulting electrospun and dry nano- fiber polymer material is calcified at preferably at 800 oC for preferably 2 hours. If carbon is not completely removed and the purity of the resulting material is not at a satisfactory level, the product is subjected to another thermal process preferably at the same temperature and preferably under air atmosphere. The oven can be fed with oxygen gas as desired in order to increase the efficiency of the combustion process and decrease the combustion time. The material can then preferably be grinded and pressed as pellet form."