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Jayaweera P.M.,University of Sri Jayewardenepura | Jayaweera P.V.V.,SPD Laboratory Inc. | Jayasundara U.L.,University of Sri Jayewardenepura | Jayaweera C.D.,University of Sri Jayewardenepura | And 2 more authors.
Transactions of the Institutions of Mining and Metallurgy, Section C: Mineral Processing and Extractive Metallurgy | Year: 2011

The rate of leaching of iron from ilmenite (FeTiO 3) in hydrochloric acid (HCl) solutions is greatly enhanced by the presence of ultraviolet (UV) light. The magnitude of the air purged UV light illuminated leaching rate is approximately twofold higher than the N 2 purged leaching rate under dark conditions. The enhanced rate is attributed to the photo dissociation of polymeric titanium oxy species via oxidising radicals OH and HO 2 formed through Fe 3+/Fe 2+/H 2O Fenton type reactions. Photo dissociation and consequent non-deposition of polymer species in the pores of ilmenite particles cause the chemical reaction between FeTiO 3 and HCl acid in stirred solutions to become the rate determining step. The addition of H 2O 2 to the reaction mixture, in the presence and absence of UV light, further enhances iron leaching rate, confirming the role of radical species. © 2011 Institute of Materials. Source


Jayaweera P.V.V.,SPD Laboratory Inc. | Pitigala P.K.D.D.P.,Georgia State University | Shao J.F.,Georgia State University | Shao J.F.,Lanzhou University | And 6 more authors.
IEEE Transactions on Electron Devices | Year: 2010

A low-cost photoconductive dual-band detector based on a ZnO film sensitized with lead sulfide quantum dots (PbS-QDs) is reported. The UV response arises from the interband absorption of UV radiation by ZnO, and the IR response is due to the absorption in the PbS-QDs. The detector exhibits UV response from 200 to 400 nm with a peak responsivity of 4.0×105 V/W and detectivity D of 5.5× 1011 Jones at 370 nm at room temperature. The observed visiblenear IR response is from 500 to 1400 nm with a responsivity of 5.4×105 V/W and D of 7.3×1011 Jones at 700 nm operating at room temperature. By increasing the PbS-QD size, the IR response can extend up to 2.9 μm. © 2006 IEEE. Source


Liyanage D.,University of Shizuoka | Bandara H.M.N.,University of Peradeniya | Jayaweera V.,SPD Laboratory Inc. | Murakami K.,University of Shizuoka
Applied Physics Express | Year: 2013

Fluorine-doped tin oxide nanorod transparent thin films were fabricated with SnCl4·5H2O, NH4F, and ethylene glycol (EG) using an improved spray pyrolysis deposition technique. The fabricated nanorods showed a low resistance of 15.3Ω/sq and a good transparency of 70.8%. The nanorods have a higher surface area than the conventionally used thin films. © 2013 The Japan Society of Applied Physics. Source


Premalal E.V.A.,University of Shizuoka | Dematage N.,University of Shizuoka | Kaneko S.,SPD Laboratory Inc. | Konno A.,University of Shizuoka
Thin Solid Films | Year: 2012

Fluorine-doped tin oxide (FTO) thin films were prepared, at different substrate temperatures, using dilute precursor solutions of di(n-butyl)tin(iv) diacetate (0.1 M DBTDA) by varying the F - concentration in the solution. It is noticed that conductivity of FTO film is increasing by increasing the fluorine amount in the solution. Morphology of SEM image reveals that grain size and its distribution are totally affected by the substrate temperature in which conductivity is altered. Among these FTO films, the best film obtained gives an electronic conductivity of 31.85 × 10 2 Ω - 1 cm - 1, sheet resistance of 4.4 Ω/□ (ρ = 3.14 × 10 - 4 Ω cm) with over 80% average normal transmittance between the 400 and 800 nm wavelength range. The best FTO film consists of a large distribution of grain sizes from 50 nm to 400 nm range and the optimum conditions used are 0.1 M DBTDA, 0.3 M ammonium fluoride, in a mixture of propan-2-ol and water, at 470 °C substrate temperature. The large distribution of grain sizes can be easily obtained using low DBTDA concentration (~ 0.1 M or less) and moderate substrate temperature (470°C). © 2012 Elsevier B.V. Source


Premalal E.V.A.,University of Shizuoka | Dematage N.,University of Shizuoka | Kaneko S.,SPD Laboratory Inc. | Konno A.,University of Shizuoka
Electrochemistry | Year: 2012

Fluorine-doped tin oxide (FTO) thin films were prepared, at different substrate temperatures, using dilute precursor solutions of di(n-butyl)tin(iv) diacetate (0.1 M DBTDA) by varying the F - concentration in the solution. Morphology of SEM image revels that grain size and its distribution are affected by the substrate temperature. At the lowest temperature (400°C) the grain size become the smallest and at the highest temperature grain size become larger while at moderate temperature it has a large distribution of grain sizes. XPS calculation reveals that fluorine doping will decrease when substrate temperature is increased. Carrier concentration measured from hall coefficient analysis is found to be varying with the amount of fluorine doping as well as with the surface area of the film. Mobility becomes the lowest for the lowest grained FTO and it is the highest for the largest grained FTO. The best film, has large distribution of grain sizes (50-400 nm), gives an electronic conductivity of 31.85 Χ 10 2Ω -1cm -1, sheet resistance of 4.4fi/square with over 80% transmittance (400-800 nm). Optimum conditions of the best FTO film were 0.1 M DBTDA, 0.3 M ammonium fluoride, in a mixture of propan-2-ol and water, at 470°C substrate temperature. Dye-sensitized solar cells were fabricated using both the FTO films thus prepared and with the commercial FTO film. The best efficiency of 6.48% was observed for the cell fabricated from the best FTO films prepared at 470°C whereas the cells fabricated from the commercial FTO shows 5.30% light-to-electricity conversion efficiency (Illumination-A.M 1.5, Cell active area-1 cm 2, MPN based electrolyte-I -/I 3 -). © The Electrochemical Society of Japan All rights reserved. Source

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