F. Yakuphanoglu

Structural and optical properties of nanostructure CdZnO films.

CdZnO thin films with different ratio of CdO and ZnO (3:1, 1:1, and 1:3) were grown on glass substrate using sol-gel spin coating method. The morphology of the CdZnO films depends on the amount of ZnO and CdO in the films. The optical band gap of the CdZnO films depends on the compositions of CdO and ZnO. Films having higher amount of CdO shows the presence of grains along with the fiber nature of ZnO, whereas the film with lower percentage of CdO shows fiber nature of the film very similar to pure ZnO film. The optical bandgap of CdZnO (3:1), CdZnO (1:1), and CdZnO (1:3) films was calculated to be 2.80, 2.49, and 2.52 eV, respectively. Other optical properties such as refractive index, extinction coefficient, and dielectric constants were calculated using the optical data. The volume and surface energy loss functions were also calculated and observed to increase with increase in the photon energy.

Strontium substituted hydroxyapatites: Synthesis and determination of their structural properties, in vitro and in vivo performance.

The objective of this study is to present a detailed report related to the synthesis and characterization of strontium substituted hydroxyapatites. Based on this purpose, hydroxyapatite (HAp) bioceramics with different amounts of strontium (e.g., 0, 0.45, 0.90, 1.35, 1.80 and 2.25 at.%) were prepared using a sol-gel method. The effects of Sr substitution on the structural properties and biocompatibility of the samples were studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques, in vitro and in vivo tests. All the samples composed of the nanoparticles ranging from 21 to 27 nm. The presence of Sr at low levels influenced the crystal size, crystallinity degree, lattice parameters and volume of the unit cell of the HAp. Both in vitro conditions and soaking period in simulated body fluid (SBF) significantly affected these properties. Especially, the (Ca+Sr)/P molar ratio gradually decreases with increasing soaking period in SBF. Animal experiments revealed the bone formation and osseointegration for all samples, and as compared with other groups, more reasonable, were observed for the sample with the lowest Sr content.

Electrical and optical properties of newly synthesized glyoxime complexes

Abstract In this study, the electrical and optical properties of newly prepared Ni(L 1 H 2 ) and Ni(L 2 H 2 ) complexes have been investigated and the results obtained were analyzed. It is seen that these complexes have inorganic semiconductor properties. The activation energies ( E a ) for the complexes were calculated by using Arrhenius plots and their optical band gaps have been determined through the optical spectra. Thermal probe measurements indicated that these samples have n -type of electrical conductivity.

Solid state electrical conductivity properties of copper complexes of novel oxime compounds containing oxolane ring

Abstract In this study, a novel dioxime having the 1,3-oxolane group, 1,2-dihydroxyimino-3,7-diaza-9,10-O-cyclohexylidenedecane (L1H2) and 9,10,bis(hydroxyimino)-4-8,11,15-tetraaza-1,2,17,18-O-dibenzaloctadecane (L2H2), were synthesised from 1,2-O-benzal-4-aza-7-aminoheptane, which was prepared from a reaction of 1-choloro-2,3-O-benzalpropane and dichlorogloxime. The electrical properties of complexes of those ligands with Cu(II) salts were investigated and obtained results were analyzed. It was seen that these complexes had semiconducting properties. The activation energies (Ea) were calculated for the complexes by using the Arrhenius plot. Thermal probe measurement indicated that these complexes had an n-type electrical conductivity.

Photoluminescence and refractive index dispersion properties of ZnO nanofibers grown by sol–gel method

Zinc oxide thin film was grown on glass substrate using sol-gel spin coating method. The optical constants and dispersion energy parameters of the zinc oxide thin film were determined using optical characterization method. The optical band gap of the n-type ZnO semiconductor was found to be 3.24 eV. The refractive index dispersion of the ZnO obeys the single oscillator model. The dispersion energy and oscillator energy values of the ZnO film were found to be 13.74 eV and 6.61 eV, respectively. The real and imaginary parts of the dielectric constant of the ZnO film were determined. The photoluminescence spectra of the ZnO film indicate a peak around 401 nm (3.10 eV) due to the electron transition from the energy level of interstitial Zn to valance band and the another peak is observed around 530 nm (2.34 eV) which is attributed to the oxygen vacancies in ZnO.

A spectroelectrochemical study on single-oscillator model and optical constants of sulfonated polyaniline film.

The optical properties of sulfonated polyaniline (SPAN) thin film prepared by electrochemical method have been investigated. Polychromic behavior of SPAN thin film (transparent yellow-green-dark blue) was observed when the cyclic voltammograms were taken between -0.25 V and +1.90 V (vs. Ag/AgCl, sat.) during the growth of polyaniline film. In situ UV-vis spectra of the polymers-indium tin oxide (ITO) glass electrode were taken during the oxidation of the polymers at different applied potentials. The direct band gap values of SPAN thin film changed from 3.771 eV to 3.874 eV with the applied potentials. From in situ UV-vis spectra, the optical constants such as refractive index and dielectric constant of the SPAN thin film were determined. The important changes in absorption edge, refractive index and the dielectric constant were observed due to the applied potentials. The refractive index dispersion curves of the film obey the single-oscillator model and oscillator parameters changed with the applied potentials. The most significant result of the present work is in situ spectroelectrochemical method, which can be used to modify the optical band gaps and constants.

X-ray diffraction studies, electrical and optical properties of some metal complexes of the ligand including 1-amino-3-(N-benzylamino) propane

Abstract Metal complexes containing Cu +2 , Ni +2 and Cd +2 of the ligand including 1-amino-3-( N -benzylamino propane) named M2 — [CdL 1 ](Cl 2 ), M3 — [CuL 2 ](NO 3 ) 2 , M4 — [CuL 2 ](Cl 2 ) and M5 — [NiL 2 ](Cl 2 ) were investigated structurally by X-ray diffraction (XRD), electrically by two probe and optically by optical methods. From the XRD data, the unit cells of the samples were found as M2, monoclinic, and M3, M4 and M5, triclinic. Hot probe and thermoelectric power measurements indicated that the complexes M2, M3, M4 and M5 have n-type of electrical conductivity and optical band gaps of the complexes are 1.66, 1.31, 1.25 and 1.29 eV, respectively.

Modification of electrical properties of Al/p-Si Schottky barrier device based on 2′-7′-dichlorofluorescein

The charge conduction mechanism and electrical properties of Al/p-Si Schottky barrier device based on 2′-7′-dichlorofluorescein (DCF) were investigated by current density–voltage (J–V) and capacitance–voltage (C–V) methods. Thin film of DCF organic compound was deposited on p-Si substrate as an interfacial layer by spin-coating technique. The dark J–V characteristics indicate that the rectifying junction is formed at DCF/Al interface. The ideality factor and barrier height of the Al/DCF/p-Si Schottky diode are higher than that of Al/p-Si Schottky diode. The effect of the thickness of the DCF organic layer was investigated by evaluating electrical parameters, such as the barrier height, ideality factor, series resistance, and interface state density. It is seen that the thickness of the DCF layer significantly affects the electrical properties by influencing the space charge region of the Al/DCF/p-Si Schottky junction. The interface state density of the diode was determined using low-high frequency C–V plots and was of order of ≈1011 eV−1cm−2. The order of the interface state density of Al/DCF/p-Si is lower than most of metal/organic compound/inorganic semiconductor devices. The values of the barrier height of the studied diodes are significantly larger than those of conventional Al/p-Si Schottky diodes. The J–V curves in the reverse direction are taken and interpreted via both Schottky and Poole–Frenkel effects. Poole–Frenkel effect was found to be dominant in the reverse direction.The charge conduction mechanism and electrical properties of Al/p-Si Schottky barrier device based on 2′-7′-dichlorofluorescein (DCF) were investigated by current density–voltage (J–V) and capacitance–voltage (C–V) methods. Thin film of DCF organic compound was deposited on p-Si substrate as an interfacial layer by spin-coating technique. The dark J–V characteristics indicate that the rectifying junction is formed at DCF/Al interface. The ideality factor and barrier height of the Al/DCF/p-Si Schottky diode are higher than that of Al/p-Si Schottky diode. The effect of the thickness of the DCF organic layer was investigated by evaluating electrical parameters, such as the barrier height, ideality factor, series resistance, and interface state density. It is seen that the thickness of the DCF layer significantly affects the electrical properties by influencing the space charge region of the Al/DCF/p-Si Schottky junction. The interface state density of the diode was determined using low-high frequency C–V plo...

Electrical conductivity, dielectric permittivity and thermal properties of the compound aqua[bis(2-dimethylaminomethyl-4-NIT-phenolato)] copper(II) including NaCl impurity

Abstract The AC and DC conductivity, the dielectric permittivity and the thermal properties of the compound aqua[bis(2-dimethylaminomethyl-4-NIT-phenolato)] copper(II) including NaCl impurity were investigated. The AC conductivity follows a power law of the frequency σ(ω)∝ωs. At high frequency, where s is dependent of temperature, the conduction mechanism is reasonably well interpreted in terms of the correlated barrier hopping model. The DC conductivity indicates classical semiconductor behavior. So, it is evaluated that the sample is a typical inorganic semiconductor as its conductivity increases with increasing temperature and the electronic parameters such as activation energy and room-temperature conductivity are in the regime of semiconductors. It is also found that the dielectric constant and the dielectric loss values decrease with frequency and increase with temperature. The thermal properties were investigated under non-isothermal conditions by thermogravimetry (TGA) and differential scanning calorimetry (DSC). The kinetic parameters such as the order of the reaction, the activation energy (E), enthalpy of formation (ΔH) and characteristic temperatures of the exothermic peak were determined by means of the TGA and DSC techniques. The thermal conductivity shows enhancement with increasing temperature and, in the thermal conductivity mechanism, dominates transport of electrons.

Fabrication and electrical characterization of flower-like CdO/p-Si heterojunction diode

The electrical properties of a flower-like CdO/p-Si heterojunction diode have been investigated in the temperature range 80–400 K. The CdO thin film was deposited on p-type Si using the sol–gel spin coating method. The scanning electron microscope result indicates that the film has a flower-like structure. From the x-ray diffraction result, it is shown that the CdO film has a polycrystalline structure with preferential orientation along the (1 1 1) crystal plane. The optical band gap of the CdO film was found to be 2.57 eV. The ideality factor is n 2 which is due to the presence of non-ideal contact behaviour and the result of inhomogeneity and tunnelling. At lower temperatures, the charge transport mechanism results from the tunnelling mechanism, whereas at higher temperatures, it is controlled by recombination currents. The capacitance–voltage characteristic shows a typical abrupt heterojunction.