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Amr A. Nada, Hanaa Selim and Mikhael Bechelany

Abstract

The dye-sensitized solar cells made of NiO@ZnO nanoparticles were synthesized by a novel Pechini route using different NiO molar concentration ratios. The thermal, structural morphological, optical and electrical properties of the prepared samples were investigated using thermal gravimetric analysis and differential scanning calorimetery (TGA/DSC), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), FT-IR and Raman spectroscopy, UV-diffuse reflectance (UV-DRS), photoluminescence (PL) and current-voltage (I-V) measurements. The success of doping process was confirmed by the XRD patterns, which revealed the existence of new peak at 43.2° corresponding to secondary phase NiO. UV spectra exhibited red shifts in NiO doped ZnO NCs and PL spectra showed strong emission band at 355 nm. The doping of ZnO with NiO was intended to enhance the surface defects of ZnO. The current-voltage measurements showed an improvement of the short circuit photocurrent (Jsc) and fill factor (FF) and a decrease in the open circuit voltage (VOC) for dye-sensitized solar cell (DSSC) based on NiO-ZnO NCs. A clear enhancement in efficiency of DSSC from 1.26±0.10 % for pure ZnO to 3.01±0.25 % for NiO-ZnO NCs at the optimum doping with 1.5 mol% of NiO to ZnO (ZN1.5) was observed. The obtained material can be a suitable candidate for photovoltaic applications.

Open access

S. Khodorov, M. Karpovski, I. Feldman and V. Shelukhin

Abstract

Direct writing of low resistance wires on an amorphous Ge-Sb-Te matrix is reported. A 1342 nm continuous wave laser was used for local heating of the sample to form these wires. Mechanical contact was not needed for making the conducting elements. The properties of the samples were investigated down to 1.4 K and the laser conditions required for the writing of low resistance GST wires were found. The results are discussed with a view to possible applications, such as connectors and electrical wires made only via remote light exposure of the samples to make different resistors and non-linear elements

Open access

K.V. Madhuri and M. Bujji Babu

Abstract

Tungsten trioxide (WO3) thin films were prepared by thermal evaporation technique on thoroughly cleaned glass substrates at high pressure of 133.322 mPa in presence of argon. The substrate temperature was maintained from 6 °C to 8 °C with the help of a cold jar. The deposited films were annealed at 400 °C in air for about 2 hours. The films were characterized in terms of their composition by X-ray photoelectron spectroscopy. Subsequently, the laboratory developed dry lithiation method was used to intercalate lithium atoms into as-deposited films in various proportions. With the amount of lithium content inserted into the film, the films showed coloration in visible and near infrared regions. The morphology, coloration efficiency and optical constants of annealed and lithiated films were calculated.

Open access

D. Pieniak

Abstract

The objective of this paper was study and analysis of damaging process of multi-ply structure applied in dentistry. The aim was to analyze and experimentally evaluate tolerance of macro-damage of first ply (FPF - first ply failure) of multi-ply composite. A studied structure of composite makes a carrying structure for dental applications e.g. adhesive bridges. Influence of reinforcement structure on the residual carrying capacity of the studied multi-ply materials has been demonstrated. It has been shown that the type of fiber and fiber ribbon architecture play a major role in strength of studied reinforcements. Structures included in the study differ by the moment of macro-damage occurrence, carrying capacity and residual stiffness.

Open access

Mieczysław Szczypiński, Kazimierz Reszka and Michał M. Szczypiński

Abstract

The subject of this research is the structure of a Si nanolayer deposited on a FeCrAl wire surface by means of magnetron sputtering method. Si layer was selected as one of possible protections of the wire surface against excessive corrosive-erosive wear. In order to increase the power necessary for the DC discharge of the magnetron with Si cathode, a second magnetron with an aluminum disc as a cathode was used. The wire was attached to a carousel holder to ensure its rotation around the magnetron. The thickness of the deposited layers was about 150 nm. A wire surface examination indicated the presence of defects such as gaps between grains, cavities as well as severely deformed grains of surface layer. The research was conducted on the sample sections which had been prepared by focused ion beam method (FIB). The technique of transmission microscopy, which was used for observation, allowed us to obtain images in bright field (BF), dark field (DF), as well as in high resolution (HREM). The studies were also performed on the wire surface after the cutting process of the expanded polystyrene blocks. A metallographic optical microscope Nikon MA200 with a large depth of field was used for the examination which showed the presence of carbon deposit products. Additionally, a composition microanalysis was carried out along the line within selected areas of samples, with the use of energy dispersive spectroscopy (EDS). A large impact of wire surface defects on Si layer forming was found as well as a high direct homogeneous growth. The examination of the sections indicated the existence of a mechanism of defects sealed by Si layer, where directionality of grains growth in these areas revealed the tendency for vertical location relative to defects surface. Consequently, closed nanopores, i.e. spaces not covered with Si layer, were created. It is a characteristic feature of areas with defects covered with an oxide film created in a natural way.

Open access

S.H. Jabarov, V.B. Aliyeva, T.G. Mammadov, A.I. Mammadov, S.E. Kichanov, L.S. Dubrovinsky, S.S. Babayev, E.G. Pashayeva and N.T. Dang

Abstract

Raman spectroscopy measurements of a monoclinic layered semiconductor TlGaSe2were performed in a pressure range up to 10.24 GPa. The pressure-induced first-order phase transition accompanied by reconstruction of the layer structure was observed at the pressure P ~ 0.9 GPa. The mode-Grüneisen parameters of intralayer bonds were calculated for TlGaSe2. The contribution of thermal expansion to temperature changes of phonon frequencies was defined. The type of intralayer bonds and their pressure transformation were analyzed in layered TlGaSe2. It was shown that the nature of intramolecular forces in molecular crystals and intralayer forces in layered GaS, GaSe and TlGaSe2is similar

Open access

R. Vasanthakumar, W. Nirmala, R. Santhakumari, R. Meenakshi and A. Sinthiya

Abstract

4-aminopyridinium adipate monohydrate (4APA) was grown by slow evaporation solution growth technique. The functional groups in the grown crystal were identified from FT-IR spectral evaluation. The optical properties together with transmittance of the grown crystal were obtained from UV-Vis spectroscopic study. The mechanical and thermal properties of the grown crystal were studied using Vickers microhardness and TGA/DTA analyses, respectively. Microhardness test revealed that 4-aminopyridinium adipate monohydrate crystal is a soft category material. The density functional method (DFT) was performed using B3LYP with the 6-311G (d,p) basis set. The electronic charge distribution, reactivity of the molecules and the molecular electrostatic potential (MEP) of the grown crystal were analyzed using the B3LYP method. The intermolecular interactions that exist in the crystal structure of the 4APA have also been investigated by Hirshfeld surface analysis. The nonlinear optical properties of the 4APA crystal were confirmed by Kurtz-Perry technique.

Open access

Bartłomiej Dec, Mateusz Ficek, Michał Rycewicz, Łukasz Macewicz, Marcin Gnyba, Mirosław Sawczak, Michał Sobaszek and Robert Bogdanowicz

Abstract

The main subject of this study are molecular structures and optical properties of boron-doped diamond films with [B]/[C]ppm ratio between 1000 and 10 000, fabricated in two molar ratios of CH4-H2mixture (1 % and 4 %). Boron-doped diamond (BDD) film on the fused silica was presented as a conductive coating for optical and electronic purposes. The scanning electron microscopy images showed homogenous and polycrystalline surface morphology. The Raman spectroscopy confirmed the growth of sp3 diamond phase and sp2carbon phase, both regular and amorphous, on the grain boundaries, as well as the efficiency of boron doping. The sp3/sp2ratio was calculated using the Raman spectra deconvolution method. A high refractive index (in a range of 2.0 to 2.4 at λ= 550 nm) was achieved for BDD films deposited at 700 °C. The values of extinction coefficient were below 1.4 at λ= 550 nm, indicating low absorption of the film

Open access

I.S. Yahia, Mohd. Shkir, V. Ganesh, M.M. Abutalib, H.Y. Zahran and S. Alfaify

Abstract

Herein, we report a successful development of nano-scale pure and Al and Mn co-doped PbI2 using facile microwaveassisted route. Structural study was done through X-ray diffraction analysis of grain size, dislocation density and lattice strain. The crystallite size was found to vary from 28 nm to 40 nm due to Al:Mn co-doping in PbI2. The presence of various vibrational modes was confirmed by FT-IR spectroscopy and red shifting was observed in peak positions compared to the bulk. Surface morphology, examined using a scanning electron microscope, confirmed the formation of single crystal nanosheets of a thickness in the range of 10 nm to 30 nm. The single crystal nanosheets were found to be transformed to large area nanosheets due to the doping. Enhancement in dielectric constant from ~7.5 to 11 was observed with increasing Al doping concentration. Linear attenuation coefficient was calculated and showed the enhancement of blocking gamma rays with increasing doping concentration. Its value was found to increase from 7.5 to 12.8 with the doping. The results suggest that the synthesized nanostructures can be used for detection and absorption of gamma rays emitted by 137Cs and 241Am sources.

Open access

C.H. Voon, B.Y. Lim, S.C.B. Gopinath, Y. Al-Douri, K.L. Foo, M.K. Md Arshad, S.T. Ten, A.R. Ruslinda, U. Hashim and V.C.S. Tony

Abstract

Cuprous oxide, a narrow bandgap p-type semiconductor, has been known as a potential material for applications in supercapacitors, hydrogen production, sensors, and energy conversion due to its properties such as non-toxicity, easy availability, cost effectiveness, high absorption coefficient in the visible region and large minority carriers diffusion length. In this study, Cu2O nanostructured thin film was fabricated by anodizing of Cu plates in ethylene glycol containing 0.15 M KOH, 0.1 M NH4F and 3 wt.% deionized water. The effects of anodizing voltage and temperature of electrolyte were investigated and reported. It was found that nanoporous Cu2O thin film was formed when anodizing voltages of 50 V and 70 V were used while a dense Cu2O thin film was formed due to the aggregation of smaller nanoparticles when 30 V anodizing voltage was used. Nanoplatelets thin film was formed when the temperature of electrolyte was reduced to 15 °C and 5 °C. X-ray diffraction confirmed the presence of Cu2O phase in thin film formed during anodizing of Cu plates, regardless of the anodizing voltage and temperature of electrolyte. Photoluminescence spectroscopy showed the presence of Cu2O peak at 630 nm corresponding to band gap of 1.97 eV. A mechanism of the formation of Cu2O thin film was proposed. This study reported the ease of tailoring Cu2O nanostructures of different morphologies using anodizing that may help widen the applications of this material