Papers by Keyword: Zinc Oxide (ZnO)

Abstract: Efficient light management in solar cells can be achieved by incorporating plasmonic nanoscatterers that support surface plasmons: excitations of conduction electrons at the interface/surface. As known, light trapping increases the amount of light absorbed by bouncing the light within the cell, giving it a chance to be absorbed thereby increasing the absorption and scattering cross-section. The challenge is to fabricate these plasmonic nanoparticles in cost-effective method as well as without hampering optical, electrical and topographical properties of underneath layers. Here in this report a simple two step method was adopted to fabricate silver nanoparticles on zinc oxide followed by topographic and elemental analysis thereof. Numerical calculation was carried out to elucidate optical scattering of silver nanoparticles of various sizes as well as that of dimer. Near-electric field distribution of single silver nanoparticles and dimer along with the individual component of electric field was simulated by finite different time domain analysis. Using the benefit of increased scattering cross-section and ease of such nanoparticles fabrication, a cell configure is proposed herewith.

Abstract: Zinc and iron oxide nanoparticles were synthesized using natural bio-polymeric templates viz. cellulose and sodium alginate. Cellulose fibres from different sources viz. filter-and blot-papers, were used as templates for this purpose. The synthesized Zinc oxide nanoparticles were characterized by X-ray diffraction (XRD), fourier transform infra-red spectra (FT-IR), UV-Visible spectrophotomer (UV-Vis) and scanning electron microscopic (SEM) studies. XRD studied confirmed the formation of highly crystalline hexagonal wurtzite phase of ZnO in all the synthesized nanoparticles. The average crystallite sizes of the nanoparticles obtained using different templates, were well below 50 nm. Characteristics of the zinc oxide nanoparticles obtained by template-based techniques were compared with those obtained by co-precipitation technique. Influence of various templates on the characteristics of metal oxide nanoparticles was studied.

Abstract: ZnO nanowalls were synthesized by chemical vapor deposition at temperature of 650 °C for 1 hour on the silicon substrate. The morphologies of samples were characterized by scanning electron microscopy (SEM). The result from X-ray diffraction (XRD) confirmed that the ZnO nanowalls were vertical c-axis orientation. A room temperature Photoluminescence peak at 378 nm is ultraviolet emission (UV) and the broad peak at wavelengths around 450-650 nm is corresponding to the green emission of ZnO nanostructure. This synthesis may be applicable for gas sensor or solar cells.

Abstract: This study aimed to use the zinc dust which is a waste from hot-dip galvanizing plant for the synthesis of ZnO nanoparticles using microwave-assisted process. The precursor solution was prepared by dissolved as received zinc-dust powder in nitric acid. Then it was precipitated by NaOH at required pH and microwave irradiated in a household microwave oven at power of 100W for 10-20 min. The effects of preparation conditions and an addition amount of poly ethylene glycol (PEG; MW2000) for synthesis of ZnO on its properties were investigated. The synthesized nanoparticles were characterized for their phase structure, morphology and surface area by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET), respectively. The photocatalytic activity was determined by the degradation of methylene blue solution under UV irradiation. It was found that microwave heat treatment and addition of optimum amount of PEG could enhance the photocatalytic activity of precipitated ZnO particles. The resultant ZnO particles prepared by an addition of 0.25wt% PEG and microwave irradiation for 20 min exhibited the highest photodegradation rate among other products.

Abstract: This study investigated the effect of aluminium dopant on ZnO morphologies synthesized by microwave assisted method. The precursors used were Zn (NO₃)₂.6H₂O, NaOH and AlCl₃.6H₂O. The conditions for microwave heating were 160 and 640W, 10 min with 5s ON/15s OFF step. Microwave assisted heating generates heat to activate the formation of ZnO. Phase study was carried by X-ray diffraction which confirmed the formation of wurtzite structure of ZnO for all synthesized conditions. Microstructure was studied by a scanning electron microscope which revealed different crystal morphologies of ZnO at different amount of Al doping concentrations. ZnO rod was about 3-5 μm in length and 200 500 nm in cross section with hexagonal crystal plane. During microwave heating, nucleation of ZnO rods started at a point leading growth into larger flowers. In this work, it was suggested that Al acted as a nucleating agent and affected the c-axis orientation for ZnO crystal growth. Small needles/rod-like crystals were observed probably due to fast nucleation and a decrease of growth on (002) plane.

Abstract: A simple method for obtaining ZnO-Fe₃O₄ nanocomposites using solid-state reaction Zn + 3Fe₂O₃ ZnO + 2Fe₃O₄ is suggested. An analysis of the characteristics and properties of ZnO-Fe₃O₄ nanocomposites was carried out by a combination of structural and physical methods (X-ray diffraction, scanning electron microscopy, photoelectron spectroscopy, Mössbauer measurements, X-ray fluorescent analysis, and magnetic measurements). The magnetization of the hybrid ZnO-Fe₃O₄ films is equal to 440 emu/cm³. The resulting Fe₃O₄ nanoparticles are surrounded by a ZnO shell and have sizes ranging between 20 and 40 nm.

Abstract: Zinc oxide (ZnO) is a low toxicity and environmentally friendly material, and it is applied on devices, sensors or actuators for trending towards green-life. A porous ZnO film deposited by a rapid process of aerosol deposition (AD) was employed as the gas-sensitive material in a CO gas sensor for reducing the manufacturing cost and time, further extending the AD application. A relative resistance change (R / R) of the ZnO gas sensor was used for CO gas measurement. The sensitivity of the fabricated ZnO gas sensors had a more outstanding performance about 49%, compared to the literature data reported by Joshi.

Abstract: Zinc oxide (ZnO) thin films were deposited by radio frequency (RF) magnetron sputtering technique on glass substrates in pure argon gas. The optical transmission stectra of the films were measured by ultraviolet-visible spectrophotometer. The effects of argon gas pressure on optical properties of the deposited films were investigated. The optical band-gap of the films was evaluated in terms of the Taucs law. The results show that the argon gas pressure has slightly affected the optical band-gap of the deposited films. Furthermore, the refractive index and extinction coefficient of the films were determined by means of the optical characterization methods. Meanwhile, the dispersion behavior of the refractive index was studied by the single-oscillator model of Wemple and DiDomenico, and the physical parameters of the average oscillator strength, average oscillator wavelength, oscillator energy, the refractive index dispersion parameter and the dispersion energy were obtained.

Abstract: Multi-component blends of polypropylene (PP), ethylene-1-octene copolymer (EOC) and zinc oxide (ZnO) are prepared by melt mixing using two-roll mill. Samples prepared by compression moulding have been investigated by using differential scanning calorimeter (DSC). It is found that addition of ZnO particles decreases PP melting point and increases crystallinity degree of PP. ZnO works as nucleation agent for PP by increasing quantity of crystallization centers, but at the same time decreasing structure quality. Because of the structure change mechanical properties are affected. At lower nanoparticle concentration some reinforcement effect I observed, while at higher particles concentration brittlening occurs. Crystalline structure and particles nature increases thermal stability of PP and PP/EOC blends.

Abstract: The structure of ZnO thin films grown in room temperature by reactive DC sputter technique on polyethylene terephthalate film were evaluated by SEM and TEM. The quality of ZnO thin films grown in room temperature were observed to vary widely. ZnO crystals grow without uniform orientation in early stage of growth, and then ZnO crystallinity improves as the ZnO thin films grow up. And ZnO crystallinity is influenced by roughened surface of PET film.