In the present work, nanocrystalline disodium 6-hydroxy-5-[(2-methoxy-5-methyl-4-sulfophenyl) azo]-2-naphthalenesulfonate (AR) thin films based devices were prepared by using electro-spin technique under best conditions. The nanostructure characteristics of the AR surfaces were found to be nanosphere-like structure by using scanning electron microscopy (SEM). The dark and 100 mW/cm(2) illuminated current density voltage (J-V) characteristics of the prepared heterojunctions by using different metal like Pt, Al and Cu were discussed at a temperature of 300 K. A diode-like behavior was obtained for all the studied devices and the rectification characteristics were obtained and compared. In addition, the arrangement protection and ideality factors demonstrated high interface reliance. Exposure of light on the AR dye / different metal structures produces a photocurrent which suggests the production of free carriers in all cases with different values which elucidate that these structures are promising for optoelectronic device applications. (C) 2018 Elsevier GmbH. All rights reserved.

•The junction of Au/AlPcCl/PTCDI/ITO exhibit rectifying characteristic showing a p–n diode like behavior.•High photosensitivity for the device is observed.•The device shows an improvement in photovoltaic parameters.•The interface states density is not effective on the device performance characteristics under high frequency.

In this work, nanocrystalline thin films of 2,3-naphthalocyanine (NPC) were successfully deposited by a thermal evaporation technique at room temperature under high vacuum (∼10−4 Pa). The crystal structure and surface morphology were measured using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. A preferred orientation along the (0 0 1) direction was observed in all the studied films and the average crystallite size was calculated. Scanning electron miscroscopy (SEM) images of NPC films at different thermal treatment indicated significant changes on surface level patterns and gave clear evidence of agglomeration of nanocrystalline structures. The molecular structural properties of the thin films were characterized using Fourier transform infrared spectroscopy (FTIR), which revealed the stability of the chemical bonds of the compound under thermal treatment. The dark electrical conductivity of the films at various heat treatment stages showed that NPC films have a better conductivity than that of its earlier reported naphthalocyanine films and the activation energy was found to decrease with annealing temperature. The absorption edge shifted to the lower energy as a consequence of the thermal annealing of the film and the fundamental absorption edges correspond to a direct energy gap. The temperature coefficient of the onset and optical band gaps for the film was calculated to be −4.4 × 10−4 and −1.76 × 10−3 eV/K, respectively. The effect of thermal annealing on the photovoltaic properties of Al/NPC/ITO devices was also considered. The as-deposited device showed maximum power conversion efficiency about 0.70% under illumination of 100 mW/cm2, whereas 2.65% power conversion efficiency was achieved after annealing the samples at 500 K for 1 h.

Thin film of poly(3-octylthiophene) (P3OT) was successfully prepared using dip coating technique. The morphology and the crystal structure of the prepared thin film were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. A study on interface states density distribution and characteristic parameters of the Al/P3OT/ITO device capacitor have been made. The diode parameters such as ideality factor, series resistance and barrier height were extracted from the forward biasing J-V characteristics. The energy distribution of the interface state density D-il was determined from the forward bias J-V characteristics by taking into account the bias dependence of the effective barrier height. The C-V and G/omega-V characteristics were measured in the frequency range from 10 kHz to 1 MHz and dc biasing voltage swept from -4V to +4 Vat room temperature (300 K). The non-ideal behavior of J-V and C-V characteristics can be attributed to the presence of the interface and the series resistance. (C) 2011 Elsevier B.V. All rights reserved.

Thin films of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) were prepared by thermal evaporation technique under high vacuum at room temperature (300 K). The prepared films were identified by scanning electron microscopy (SEM), and X-ray diffraction (XRD). The capacitance-voltage (C-V) characteristics of PTCDA/n-Si heterojunction was measured at different temperatures ranging from 300 to 400 K under dark condition. The dependence of C-2 on V for the device PTCDA/n-Si was found to be almost linear which indicates that the junction is abrupt and then the essential junction parameters were obtained. The built-in potential and the acceptor carrier concentration are found to be strongly temperature dependent. Capacitance was also measured under illumination of 100 mW/cm(2) condition in the temperature range 300-400K. The capacitance of the device is found to increase with increasing illumination intensity due to the irradiated light induced electron-hole pairs in the depletion region as well as the decrease in the depletion layer. The dark current density-voltage (J-V) characteristics show the rectification effect which may be due to the formation of junction barrier at PTCDA/n-Si interface. The photovoltaic characteristics were determined by analyzing the dependence of short circuit photocurrent density J(SC) and the open circuit voltage V-oc on the illumination intensity at different temperatures. PTCDA is useful material to be used in photovoltaic devices. (C) 2011 Elsevier B.V. All rights reserved.

In this work, the organic thin films of pyronine B(PYR.B) were deposited by thermal evaporation technique under high vacuum (similar to 10(4) Pa). The crystal structure, examined by X-ray powder diffraction, indicates that the films are single phase with strong preferred (4 0 0) orientation. Scanning electron micrographs of the films indicate a clearly almost uniform distribution with large grain sizes in the range 5-10 mu m. The molecular structure and electronic transitions of PYR. B were investigated by Fourier-transform infrared (FTIR). Fluorescence characteristic of PYR. B at room temperature (300 K) exhibits visible band peak located at 569.65 nm. The color parameters were extracted from the reflectance spectrum of PYR. B. The optical constants such as refractive and extinction indices were determined from the measured transmittance and reflectance spectra using the spectrophotometric method. The dependence of absorption coefficient on the photon energy was determined and the analysis of the result showed that the optical transition in PYR. B is allowed and direct. The current density-voltage (J-V) characteristics in dark show the rectification effect due to the formation of Schottky barrier at Al/PYR. B interface. The photovoltaic parameters were calculated from the J-V characteristics under illumination through ITO and discussed in detail. (C) 2011 Elsevier B.V. All rights reserved.

The growth and importance of medical and related health care and hygiene textile sectors are attributed to the improvement and innovations in both textile technology and medical procedures. The aim of this study was to examine some of the structural properties of pure poly(vinyl alcohol) (PVA) and hydroxypropyl cellulose (HPC) doped PVA of different weight percentages. This will lead to the choice of the optimum conditions suited for specific medical and surgical applications for which textile materials are currently used. Thermogravimetry was used to develop an instrumental system for the study of thermal stability and for identification of the individual components of several polymer blends. Derivative thermogravimetry provided clear information and distinguished between different generic types. Also, differential scanning calorimetry and its derivatives gave accurate values of glass-transition temperature and melting temperature and gave detailed features of the steps of weight loss and changes in the heat of fusion. The X-ray diffraction technique was used to determine the crystallinity/amorphosity ratio and the change in crystallite size at different dopant concentrations. The effect of doping with HPC on PVA structure was studied with spectrophotometric analyses. Variations in the group coordination in the IR region were followed. The data obtained indicated that measurable and remarkable changes in the thermal stability of PVA occurred at different doping concentrations. This may have been because the diffusion of dopant caused structural changes in the polymer matrix. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1914–1923, 2005

Lithia ceramics with three Li 2 O:Al 2 O 3 :SiO 2 molar ratios 1:1:6, 1:1:8 and 1:1:10 were prepared and vitrified. The samples obtained at optimum firing conditions were selected to study the effect of developed phases including porosity on their optical properties. Spectrophotometrical analysis and applying the CIE system for total transmission including scattering and spectral reflectance were adopted. Crystallinity was defined morphologically using scanning electron microscope (SEM). The data indicated that the structure parameters being minimum crystallite size, maximum microstrain and porosity are related to SiO 2 content. The spectral behavior depended on the nature of the glassy matrix which in turn is related to the phase compositions of the ceramic and its crystallite size. Tristimulus transmittance peak values were reduced in parallel with increases SiO 2 content. Relative brightness and chromaticity revealed similarities for bodies with larger crystallite size and minimal microstrain having the lowest and highest LAS molar ratios.

Specimens of dry cortical bovine bone and bone equivalent ceramic of Ca/P ratio 1.95 were prepared and subjected to two fast neutron fluences of 1.15 x 10(6) and 1.13 x 10(8) n/cm(2). Radiation damage was assessed by following their surface morphologies (SEM) and their selected area electron diffraction (SAED) patterns of both specimens using the scanning and diffraction electron microscope techniques.The results indicated that fast neutron irradiation induced phase changes from crystalline to quasi-amorphous state. The amorphism observed in the morphological habit proved the metamictization process as complemented by SAED amorphous hallow especially with the higher fluence.

Four fritted glaze formulae were prepared using soda feldspar replacing potash one. Surface and interface of the applied glazes were followed through scanning electron microscopy and diffuse reflectance. The latter parameters were converted to the CIE system to get brightness. Pores formation in the interface were traced and related to composition. Degrees of crystallinity were assessed by measuring X-ray line broadening and were supplemented by group coordination traced by infrared analysis. It was found that the introduction of soda in frits reduced bubble formation and improved aesthetic components. Crystallite sizes varied with acidity of the glaze and the strain induced by glassy portions was followed The coordination of Al, B and Zr ions were verified. The extent and interrelation of these findings with calculated chemical composition and structural characteristics of the glazes were highlighted. Rapid rate of cooling reduced crystallite size, increased strain level and affected coordination sites of the ions.

In the present work, the effect of different doses of gamma rays ranging from 50 to 500 kGy on the transmission spectra and the tristimulus transmittance as well as the absorption coefficient in the range 400-700 nm of poly(vinyl chloride) (PVC) were studied by the optical transmission spectra. Variation in the group coordination in the near infrared region (700-3000 nm) were also studied. The data indicated that measurable and remarkable changes in the transmittance of the irradiated samples, as well as decrease in the tristimulus transmittance values, as compared to the unirradiated PVC sample were detected. Moreover, the irradiated samples acquire various colors depending on the radiation doses.Linear empirical formulae are estimated to determine gamma doses from the values of CIE translucency and the absorption coefficients of PVC at 550 and 650 mu m.

For monoporosa rapid fired tiles, eight fritted glaze formulae were designed to have soda feldspar in place of potash. Various ratios of frit/Kaolin and ZnO/ZrSiO4 were also tried. The properties of surface and interface of glazes were characterized through measuring their diffuse reflectance and pore development by scanning electron microscopy. Results were interpreted in terms of crystallite size and strain calculated from Xray line broadening. The cation coordination assessed by infrared analysis along with composition enlightened the glaze network structure. Detailed structural analyses aimed for future environmental studies. It was found that the reduced bubble formation in frits and hence elimination of pinholes and surface toughness in the glaze were related to high acidic glaze. The variation of ZnO and/or ZrSiO4 affected reflection and chromaticity as well as the size and shape of the pores developed in the interface. Results of stresses produced in the opacifier grains related to thermal expansion data of the glaze.

A newly developed bone equivalent hydroxyapatite was derived from veterinary bone (VHAP). Sections of 1 cm of six rabbit mandibles were equally replaced by this VHAP graft. Radiological studies by X-ray were performed pre-operatively, immediately, and 1, 2 and 3 months post-operatively. The graft host-bone interface was examined periodically by scanning electron microscopy (SEM). Accompanying structural changes of the graft 3 months post-operatively were compared with the pre-operative findings by infra-red (IR) spectroscopic analysis. Complete union of the biomaterial to the host bone after 3 months was evidenced radiologically. SEM proved complete graft integration. This was accompanied by a decrease in optical density of the IR analysis of post-operative VHAP, indicating some leaching of the ions. Clinically, the graft was completely incorporated in the mandible without any complications. We discuss the use of VHAP in humans to reconstruct post-surgical mandibular defects.

The induced effects by radiation with gamma (γ) and thermal neutrons (N) on the radiophotoluminiscence, microhardness indentation number as well as the electric resistivity of the cellulose acetate films are investigated. The results indicate uniform and linear changes in these physical parameters with increasing absorbed doses D γ and D N for both types of irradiation. Furthermore, the dose response as a function of these induced changes promises a dosimetric use of cellulose acetate (CA) over the ranges from 10 0 to 10 5 Gy (1 Gy = 100 rad) and from 0.3 to 50 cSv (1 Sv = 100 cSv = 100 rem, i.e. 1 cSv= 1 rem) for gamma and thermal neutron radiation doses, respectively. The fading behaviour in CA as a radiation detector is found to be stabilized after 28 days and attained relative values 10–15% considering the three different techniques of measurements.

Thermoluminescence properties of pure Al2O3-ceramic discs doped with some oxides of alkali metals and B were investigated. Two groups of samples were studied: one with a low concentration of B and alkali oxides and the other with higher concentration. The first group shows a relatively higher stability and better reproducibility for γ-radiation and neutron-induced TL, which could be utilized in mixed radiation field dosimetry. The main disadvantage of these TL-materials is the relatively high rate of signal fading. A simple course of post irradiation heat annealing is proposed to overcome this drawback.

The effect of fast neutron bombardment (2 Mev Cf-252 source) With fluence of 1.07 x 10(18) n/cm2 on the linear thermal expansion of Li-beta-alumina ceramics was studied. Two ceramic groups in which the contents of oxides of Li, Na, K as well as B increased at the expense of alumina were prepared. Induced defects in terms of X-ray diffraction analysis were discussed to assess the use and applicability of these ceramics in neutron dosimetry.The thermal expansion data indicated that both groups exhibited reduction in the mean thermal expansion coefficient values upon irradiation. This is parallel with the shift in the lattice planes of the group with higher alumina and amorphism in the other one.Annealing of the neutron induced defects at 1000 degrees C denoted that partial recovery in higher aluminous group is detected. Approximately complete recovery in the other group revealed a higher state of metamictization.

Specimens of two ceramic groups of variable alkali, boron and alumina contents were prepared and exposed to fission neutron (252Cf source). Two techniques of irradiation were used. In the first technique, each sample received an accumulative fluence up to 1010 n/cm2. After each exposure the electric parameters such as d.c. electrical resistivity, relative dielectric constant, loss angle, relative dielectric loss constant and a.c. resistivity were studied to assess the radiation effects. In the second one, various samples were irradiated with a single neutron fluence in the range 105–1010 n/cm2 before measuring the d.c. electrical resistivity. The results indicate pronounced changes in the parameters measured which may be due to the various mechanisms such as thermal diffusion and outgassing that are occurring in the ceramic bodies during and after irradiation, especially by using the second irradiation technique. The possibility of applying these induced changes in the physical properties of the specimens upon irradiation for dosimetry purposes is discussed.

High-alumina ceramic bodies having Li-β-alumina and lithium aluminate structure with variable alkali and boron contents were prepared. The optimization of the ceramic properties was assessed through measuring their vitrification parameters within firing temperatures ranging from 1100 to 1300°C. Accompanying structural changes were followed through x-ray diffraction as well as scanning electron microscopy. Their D.C. resistivity as well as dielectric properties—relative dielectric constant, loss angle, relative dielectric loss constant, and A.C. resisitivity at variable frequencies within 2–50kHz and 200–500kHz ranges at 60, 90 and 120°C—were measured. The results indicated that optimum vitrification parameters are attained at 1250°C. The presence of boron oxide enhanced densification probably through more liquid formation with lower viscosity. The dielectric results are successfully correlated with variable structure and densification.

The effects of γ- and neutron-irradiation on the DC electric resistivity of polyethylene were investigated. The DC electric resistivity of polyethylene decreases as it is irradiated with γ-doses as well as by fast neutron fluences over the ranges 102−6 × 106 Gy and 108–1011 n/cm2, respectively. Moreover, the electric resistivity of polyethylene samples is more sensitive to irradiation by fast neutrons compared with equivalent doses of γ-rays.