Browse

91 - 100 of 1,108 items :

  • Functional and Smart Materials x
Clear All
Synthesis and characterization of high-efficiency low-cost solar cell thin film

Abstract

Polycrystalline chalcogenide semiconductors play a vital role in solar cell applications due to their outstanding electrical and optical properties. Among the chalcogenide semi-conductors, CdZnS is one kind of such important material for applications in various modern solid state devices such as solar cells, light emitting diode, detector etc. Due to their applications in numerous electro-optic devices, group II-VI semiconductors have been studied extensively. In recent years, major attention has been given to the study of electrical and optical properties of CdZnS thin films. In this work, Cd1−xZnxS thin films were prepared by chemical bath deposition technique. Phase purity and surface morphology properties were analyzed using field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD) studies. Chemical composition was studied using energy dispersive spectrophotometry (EDS). Optical band gap property was investigated using UV-Spectroscopy. Electrical conductivity studies were performed by two probe method and thermoelectric power setup (TEP) to determine the type of the material. This work reports the effect of Zn on structural, electrical, microstructural and optical properties of these films.

Open access
Synthesis, Characterization and Biological Properties of Intercalated Kaolinite Nanoclays: Intercalation and Biocompatibility

Abstract

The aims of the present study were to synthesize the intercalated kaolinite samples with dimethylsulfoxide (DMSO), glutamic acid (GA), succinimide (SIM), cetylpyridiniumchloride (CPC), and hexadecyltrimethylammoniumchloride (HDTMA+); to characterize by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), and to determine the hemocompatibility and the cytotoxic effects of the intercalated kaolinite nanoclays on human lymphocytes. It was found that the intercalation with DMSO did not cause any decrease in cell viability until its maximum concentration (500 µg/mL), however, the intercalation with SIM, CPC, and (HDTMA+) causd important decreases in lymphocyte viabilities. It was determined that no significant decrease was observed in protein content of the lymphocyte cells exposed to the kaolinite nanoclays except the ones intercalated with SIM. Furthermore, the pristine kaolinite nanoclays which were intercalated with DMSO, GA, and SIM exhibited high hemocompatibility and the nanoclays intercalated with CPC and (HDTMA+) were highly hemocompatibile for the amounts below 125 and 500 µg/mL, respectively. All the results of this work can serve for the human risk assesment of intercalated nanoclays.

Open access
Trends of Joining Composite AlSi-SiC Foams

Abstract

The paper consist of characterization of the essence of structure, properties and application of AlSi-SiC composite foams as well as limitations and possibilities of their joining. Porous structure with porosity up to 80% and exceptional properties of aluminium foams are the reason of their numerous application and interest of their joining. Consideration of methods of welding, soldering and gluing AlSi9-SiC10 composite foams, the joint structure, and properties. Recommendations for surface preparation of foam, and different joining procedures aimed at control the porosity of the foam and glued surface roughness were established. Result of EDS and XRD investigations of the AlSi9-SiC10 composite foams joint were considered.

Open access
X-ray photoelectron spectroscopy (XPS) study of Heusler alloy (Co2FeAl) interfaced with semiconductor (n-Si) structure

Abstract

Layered magnetic heterostructures are very promising candidates in spintronics in which the influences of interfaces, surfaces and defects play a crucial role. X-ray photoelectron spectroscopy (XPS) study has been performed for studying in detail the chemical state and electronic structure of Co2FeAl (CFA) Heusler alloy interfaced with Si substrates. XPS survey scan spectra have clearly shown the presence of Fe, Co and Al signal along with the signal due to Si. The presence of Co, Fe and Al signal confirms the formation of CFA alloy phase. Our XPS results support our previous study [1] on CFA/Si structure in determining the magnetic and transport properties across the interface.

Open access
Analysis of surface properties of Ti-Cu-Ox gradient thin films using AFM and XPS investigations

Abstract

The paper presents results of investigations on surface properties of transparent semiconducting thin films based on (Ti-Cu)oxide system prepared using multi-magnetron sputtering system. The thin films were prepared using two programmed profiles of pulse width modulation coefficient, so called V- and U-shape profiles. The applied powering profiles allowed fabrication of thin films with gradient distribution of Ti and Cu elements over the thickness of deposited layers. Optical investigations allowed determination of transparency of prepared films that reached up to 60 % in the visible part of optical radiation, which makes them attractive for the transparent electronics domain. Surface properties investigations showed that the surface of mixed (Ti-Cu)oxides was sensitive to adsorption, in particular to carbon dioxide and water vapor. Soft etching with argon ions resulted in surface cleaning from residuals, however, deoxidation of Cu-oxide components was also observed.

Open access
Characterization of CuO/n-Si heterojunction solar cells produced by thermal evaporation

Abstract

Copper(II) oxide (CuO) in powder form was evaporated thermally on the front surface of an n-Si (1 0 0) single crystal using a vacuum coating unit. Structural investigation of the deposited CuO film was made using X-ray difraction (XRD) and energy dispersive X-ray analysis (EDX) techniques. It was determined from the obtained results that the copper oxide films exhibited single-phase CuO properties in a monoclinic crystal structure. Transmittance measurement of the CuO film was performed by a UV-Vis spectrophotometer. Band gap energy of the film was determined as 1.74 eV under indirect band gap assumption. Current-voltage (I-V) measurements of the CuO/n-Si heterojunctions were performed under illumination and in the dark to reveal the photovoltaic and electrical properties of the produced samples. From the I-V measurements, it was revealed that the CuO/n-Si heterojunctions produced by thermal evaporation exibit excellent rectifying properties in dark and photovoltaic properties under illumination. Conversion efficiencies of the CuO/n-Si solar cells are comparable to those of CuO/n-Si produced by other methods described in the literature.

Open access
Effect of MgB2 additives on structure, electrical and thermal properties of Eu1Ba2Cu3O7

Abstract

The effect of MgB2 addition on the Eu1Ba2Cu3O7 (EBCO) ceramics was systematically studied. Series of Eu1Ba2Cu3O7 + x(MgB2) samples (x = 0 wt.%, 0.05 wt.%, 0.1 wt.%, 1 wt.%, 3 wt.%) were prepared using traditional solid state method. X-ray powder diffraction measurements were used for phase identification. The lattice parameters and orthorombicity decreased with MgB2 addition. A standard four point measurement method was used to determine transition temperatures Tc of superconducting samples. Tc values of the samples were decreasing with MgB2 concentration. TGA results indicate thermal stability of doped samples.

Open access
Electrical and optical properties of new Pr3+-doped PbWO4 ceramics

Abstract

Polycrystalline samples of new scheelite-type tungstates, Pb1−3x xPr2xWO4 with 0.0098 ⩽ x ⩽ 0.20, where denotes cationic vacancies have been successfully prepared by a high-temperature solid-state reaction method using Pr2(WO4)3 and PbWO4 as the starting reactants. The influence of the Pr3+ substitution in the scheelite framework on the structure and optical properties of prepared new ceramic materials has been examined using powder X-ray diffraction method (XRD) and UV-Vis-NIR spectroscopy. The results of dielectric studies of Pb1−3x xPr2xWO4 samples showed both low values of dielectric constant (below 14) and loss tangent (below 0.2). The electrical conductivity and thermoelectric power measurements revealed a low conductivity (∼2 × 10−9 S/m) and the sign change of thermoelectric power around the temperature of 366 K suggesting the p-n transition. These results are discussed in the context of vacancy, acceptor and donor levels as well as the Maxwell-Wagner model.

Open access
Enhancement in magnetic and electrical properties of Ni substituted Mg ferrite

Abstract

In this work, Ni substituted magnesium spinel ferrites having general formula Mg1−xNixFe2O4 (where x = 0.0, 0.1, 0.15, 0.2, 0.25 and 0.3) were synthesized by standard solid state reaction method. All the samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), DC resistivity measurements. X-ray diffraction analysis confirmed the single spinel phase. The lattice constant decreased with increasing Ni content due to the difference in the ionic radii of Mg2+ and Ni2+ ions. The FT-IR spectra reveled two prominent frequency bands in the wave number range of 400 cm−1 to 600 cm−1, which confirmed the cubic spinel structure of obtained compound and completion of chemical reaction. Magnetic studies revealed that the saturation magnetization increased with the substitution of Ni. The increase in magnetization was explained on the basis of distribution of magnetic and non-magnetic cations among A and B sites of the spinel lattice. A significant influence of cation distribution on DC electrical resistivity and activation energy was observed.

Open access
Fabrication of DSSCs with biebrich scarlet, alizarine cyanine green and evans blue dyes as new organic photosensitizers

Abstract

Dye sensitized solar cells are photoelectrochemical cells mimicking photosynthesis. They represent a new generation of solar cells which is intensively studied nowadays. This cell was fabricated using TiO2 nanoparticles coated on FTO glass, organic dyes as photosensitizer, PEDOT:PSS as counter electrode and iodide-triiodide as electrolyte. The present work aims at the use of low cost new organic dyes viz. biebrich scarlet, alizarine cyanine green and evans blue for DSSC as an alternative to metallic dyes. In the present work, I-V characteristics, energy or power conversion efficiencies of the dyes have been studied in different solvents. The photoelectrochemical properties of the dyes were observed under 1.5 AM condition.

Open access