Abstract: New nanocrystals (NCs) were engineered with a core/shell/shell system consisting of CdSe core/ CdTe shell/ CdS shell. The white light generation mechanism was described depending on mixing colors from the illuminated CdSe/CdTe/CdS core/shell/shell nanocrystals. The color mixed in CdSe/CdTe/CdS core/shell/shell NCs system were used to generate extreme white light when illuminated by InGaN/GaN UV LED (λ=360 nm) the core/shell/shell NCs system tuned the chromaticity coordinates to (0.332, 0.340) and increased the intensity of the emitted white light. The synthesis of the CdSe/CdTe/CdS core/shell/shell NCs were confirmed by SEM, AFM, XRD and photoluminescence (PL) experiments due to create of surface states defects information. This enhancement was recognized to the overlap of emission with the photoluminescence (PL) spectrum of CdSe/CdTe/CdS core/shell/shell NCs which indications to a cold white light generation. Current-voltage (I–V) characteristics indicate that the output current is good compared to the few voltages (6 V) used which give acceptable results to get a generation of white light.
Abstract: The optical absorption spectrum, Photoluminesces, and non-linear optical properties for Copper Phthalocyanine (CuPc) thin films (150,300 and 450 nm) respectively have been investigated via pulsed laser deposition technique. The absorption spectrum indicted that there are two bands one in UV around 330 nm which called B-band and the second in Visible around 650nm which called Q-band. Photoluminescence spectrum related to deposit samples has been determined with different thicknesses. From closed and open aperture Z-scan data non-linear absorption coefficient and non-linear refractive index have been calculated respectively using He-Ne laser which have beam waist of (24.2 μm), wave-length of (632.8 nm) and Rayleigh thickness was 2.9 mm. Through dividing closed by open apertures, non-linear refractive index was calculated accurately. Finally, the study also showed the suitability of the deposited films as an optical limiter at the wavelength 632.8 nm.
Abstract: The objective of the present work is the study the Ni concentration effect on the optical, structural and electrical properties of ZnO:Ni thin films deposited by pneumatic spray pyrolysis method. Un-doped and Ni-doped ZnO thin films were prepared from zinc acetate dihydrate and nickel chloride hexahydrate dissolved in distilled water onto glass substrates by pneumatic spray pyrolysis method. Solution concentration, substrate temperature and nozzle-substrate distance were kept constant during all deposition processes. Effect of nickel content on the optical, structural and electrical properties of as-prepared films obtained was investigated by UV–Vis-NIR spectrophotometry, X-ray diffraction and four-point probe technique. The results indicate that the deposited films are well adherent to the substrates, present surface roughness and have a preferential growth in the (002) direction. The observed transmittance in the visible region was situated between 60% and 70%. For Ni-doped ZnO, there are two separate phases. The Urbach energy, grain size, and electrical conductivity increase with Ni content. The same behavior for both the optical energy gap and the ZnO:Ni lattice parameters.
Abstract: It has been carried out preparation of Chrom/Nanocomposite ZrO2-Pillared Bentonite catalyst with varying the amount of impregnating precursor at 0 to 3% (w/w). Material characterization of catalyst was carried out using X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Infrared Spectroscopy (IR), Transmission Electron Microscope (TEM), Brunauer, Emmett, Teller (BET) and acidity measurement of ammonia-adsorption method. The results of research showed that pillarization was able to increase the basal spacing, surface area, diameter of pore and total volume of pore in catalyst, however increasing of impregnated Cr metal on bentonite caused the decreasing of basal spacing and surface area of catalyst but it would also caused the increasing amount of acid site. The experimental results showed that the catalyst could convert the castor oil into a liquid phase of 78.80% (w/w) with a biogasoline content of 32,73% (w/w).
Abstract: Polymer concrete is one kind of which is used as an additive of the binding material. Due to their high thermal stability, tensile and flexural strengths, high compressive strength and resistance to chemical, its popularity increasing rapidly and which is now widely used as a construction material. This paper explores a research study that has been establishing a standard correlation between concrete compressive strength with the amount of polymers and other ingredients. Hence a comparison was made between the conventional concrete and polymer concrete. As per ASTM C31, the mix design of polymer concrete is calculated and estimated the material quantity. In this research, a total of twenty-two trail mixes of polymer concrete were prepared with different amount of epoxy resin and hardener. In implementation of experimental program compressive strength test was performed for conventional concrete, polymer resin (epoxy resin) concrete with resin percentage 10%, 12%, 15%, 17% and 20% was performed and compared the results with polymer concrete (no-fly ash) with polymer concrete (fly ash) percentage 15%. It was found that the compressive strength of the polymer concrete was increased with increasing the percentage of a polymer. Compressive strength of the 17% and 20% polymer resin-based polymer concrete was 46.75 MPa and 48.32 MPa and cost was around 1,17,110.00 TK and 1,37,152.00 TK; respectively and also it was observed that by using fly ash the strength of the concrete could be increased significantly. It can be said that higher strength can be achieved with a comparatively high cost. However, the cost can be reduced by proper materials selection, mix ratio, curing and adequate quality control of the material.
Abstract: The present work lies in the framework of designing polymeric fibre reinforced materials to be used in nanosatellite structures (CubeSat). In the design of any structural system for a space mission the balance between mass, stiffness and strength must be taken into account, also the used materials have to be appropriated for the space environmental conditions. The CubeSat are exposed to high radiation levels (because of the sun irradiance), and so, the accurate determination of the thermal and radiation properties are a key issue for the materials design used in such applications. This work reports the thermal and radiation performance of a biphasic epoxy resin system incorporating two types of ceramic nanoparticles: zinc oxide and graphene, chosen as potential fillers to improve the thermal properties of the epoxy system. Materials are exposed to Gamma and UV radiation at rates of 1 kGy and 10 kGy and characterized after exposure. Different characterization techniques (Thermogravimetric analysis - TGA, Scanning Electron Microscopy - SEM and Colorimetry) are performed to determine thermal properties and possible material degradation after radiation exposure. The influence of the different nanofiller in the thermal and radiation response of the epoxy system are discussed. Thermal properties found are also added to the Finite Element Analysis of a CubeSat composite structure to estimate more accurately its performance under the thermal load and service conditions during satellite life cycle.