Papers by Keyword: Spray Pyrolysis

Abstract: Structural, electrophysical and thermoelectric properties of nanoscaled In₂O₃ films doped by Sn and Zn were studied. Thin films based on In₂O₃-SnO₂ and In₂O₃-SnO₂-ZnO systems were prepared by spray pyrolysis method from water solutions of metal chlorides. It was confirmed that In₂O₃-based films, especially the In₂O₃:Sn ones, are promising material for applications related to thermoelectricity. The power factor of obtained films was found to be on the level of the best samples prepared on the base of ITO system.

Abstract: In this paper the TiO₂ nanoparticle for scattering layers were prepared using hydrolytic and non-hydrolytic sol gel route. The TiO₂ nanoparticles by hydrolytic sol gel were prepare by adding 5 ml of titanium (IV) isopropanol (TTIP) with 15 ml isopropanol. Then this TTIP mixture was added dropwise into 250 ml water with adjusted pH to 3 using nitric acids. For non-hydrolytic sol gel route 12 gram of acetylacetone, 12 gram of TTIP and 16 gram of ethanol anhydrous were mixed in a beaker under vigorous stirring. Then the prepared TiO₂ nanoparticles solutions were deposited onto TiO₂ mesoporous layer via spray pyrolysis and assemble into complete solar cell. From the XRD (X-ray diffraction) results show that the phase of TiO₂ nanoparticles formed by hydrolytic sol gel route was amorphous and for non-hydrolytic route the phase formed was mixture of anatase and rutile. The efficiency of the solar cell shows that scattering layer prepare by hydrolytic route give higher efficiency, 6.0 x 10^-5 %, as compare to scattering layer prepare by non-hydrolytic route, 4.9 x 10^-5 %.

Abstract: A nanostructured heterojunction of CdS/Cd_2x(CuIn)_1-xS₂ with x=0.2 was prepared by chemical spray pyrolysis on ITO/glass substrate at 350 °C. The X-ray diffraction pattern obtained from CdS/Cd_2x(CuIn)_1-xS₂ solar cell confirmed the formation of Cd_2x(CuIn)_1-xS₂ (CCIS), CuInS₂, In₂S₃, and CdS phases, with crystallite size of 16 nm for CCIS and 26 nm for CdS films. The morphology of the film surface was obtained by AFM technique, which produced a greater grain size of 58.3 nm for CdS and 80 nm for CCIS surfaces. Optical absorbance analysis confirmed the composition-controlled electronic transition in the thin film, and the energy band gap was observed to red shift with the increase in the value of x. The electrical properties produced a P-type conductivity of CCIS with two activation energies. I–V characteristic in dark condition produced unsymmetrical heterojunctions, whereas abrupt-type heterojunctions were produced from the C–V curve. The solar energy conversion efficiencies achieved upon illumination of 100 mW/cm² were 0.35%, 0.5%, 0.9%, and 1.28% for CCIS thicknesses of 610, 800, 910, and 1000 nm, respectively.

Abstract: ZnO-SnO₂ mixed thin films were prepared by the spray pyrolysis technique using different molar ratios of zinc and tin in the starting solution. These mixed thin films were analysed by X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). XRD patterns of mixed thin films indicate the presence of tetragonal casseterite structure of SnO₂ and hexagonal wurtzite phase of ZnO. The grain sizes of mixed films were calculated from XRD patterns and found to be in the range of 17- 84 nm. Mixed thin films exhibit smaller grain size compared to that of pure thin films. Ultraviolet and visible emission peaks were observed in photoluminescence studies of these thin films. The relative contribution of the emission bands occurring from different kinds of defects is described in detail. UV emission peaks were mostly affected by the influence of ZnO. Blue shift in UV emission peaks suggests a reduction in grain size in mixed thin film and bandgap modulation caused by SnO₂.

Abstract: Polycrystalline CuInS₂ chalcopyrite thin films were formed on a Mocoated glass substrate by annealing of a spray deposited precursor film in a sulfur atmosphere at 600 °C. Partial incorporation of Ga in the CuInS₂ film with a Ga/In ratio of ca. 0.2 to form a Cu (In,Ga)S₂ mixed crystal was also prepared. Photoelectrochemical (PEC) analyses revealed that the Ga incorporation was effective to modulate electric and semiconductive properties of the chalcopyrite film. As a result, relatively large cathodic photocurrent responses in PEC analyses as well as high photovoltaic properties of a solar cell based on the Cu (In,Ga)S₂ film were obtained.

Abstract: Zinc oxide layer have been prepared by spray pyrolysis technique. The effect of substrate temperature on structural and optical properties of the prepared layer has been investigated. XRD patterns show that ZnO layers are polycrystalline with (002) plane as preferential orientation. FESM images show that ZnO layeres consist of nanorods. Semi-conducting MEH-PPV polymer, which prepared in our lab, was dissolved in THF and sprayed on glass and KBr substrates at 150 oC with two different carrier gases. Organic-inorganic solar cell from MEH-PPV with ZnO nanorods layers was constructed, characterized and its efficiency was calculated.

Abstract: Zinc oxide (ZnO) thin films were deposited on the glass substrates using Zinc acetate dehydrate solution through spray pyrolysis method. The films were obtained by spraying 0.05M concentrated solution at a rate of 0.5ml for 10 min and were deposited at different substrate temperatures ranging from 473K to 673K. A comprehensive study was carried out to realize the effect of substrate temperatures and subsequent annealing on optical properties of the ZnO thin films. It was observed that the band gap energy decreases with increases the substrate temperature and annealing. Optical constants such as the refractive index n and extinction coefficient k were determined from transmittance spectrum in the ultravioletvisible (UVVIS) regions by Swanepoel envelope method and crystallinity was confirmed by Urbach tail and atomic force microscope images.

Abstract: The ferritic stainless steels have been used in applications where suitable properties are required at high temperatures. These metallic materials are applied, for example, as interconnects in ITSOFC fuel cells (600-800 °C).The aim of this work is to produce a La, Sr and Co based coatings using the dip-coating and spray pyrolysis techniques, on an AISI 430 ferritic stainless steel. These coatings are known for acting as barriers, increasing the oxidation resistance when applied on stainless steel at high temperatures. The obtained coatings were heat treated at 800 °C for 120 min, seeking the formation of La_0,6Sr_0,4Co,and, then characterized regarding their morphology and microstructure using scanning electron microscopy (SEM) and X-ray diffraction. The results showed that the coatings obtained by spray pyrolysis covered regularly the surface while the ones obtained by dip-coating exhibited some crack formation.

Abstract: This paper reports a brief outlook of carbon nanotubes (CNT) history, synthesis methods as well as natural carbon sources such as camphor powder, turpentine, eucalyptus, palm, neem, coconut, castor, olive, corn, sesame oil, palm olein, waste cooking palm oil and waste chicken fat.

Abstract: La-doped SrTiO₃ (LST) powders were synthesized by ultrasonic spray pyrolysis using an aqueous solution of a metal nitrate. SEM images showed that the as-prepared LST powders had a spherical morphology with a diameter of 1 μm. XRD patterns showed that the crystal phase of the as-prepared powders was amorphous and that the powders crystallized to the perovskite phase by calcination at 900 °C. The sintered LST body had the highest electrical conductivity at a La doping concentration (La_x) of 0.1 under a reducing atmosphere. A solid oxide fuel cell (SOFC) with La_0.1Sr_0.9TiO₃Sm-doped CeO₂ (1:9) as the anode exhibited a maximum power density of 137.8 mW/cm² and an open circuit voltage of 1.08 V at 880 °C.