8566

7947

كارشناسي ارشد

ماده چگال

اصفهان: دانشگاه صنعتي اصفهان، دانشكده فيزيك

1392

ده،93ص.: مصور،جدول،نمودار ﴿رنگي﴾

ص.ع.به فارسي و انگليسي

مهدي رنجبر

هادي سلامتي

7/12/92

اسماعيل عبدالحسيني سارسري، عليرضا علافچيان

فيزيك

ID7947

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Eximer laser treatment of TiO2 WO3 thin films for self cleaning gasochromic applications Sara Ghayeb Zamharir s ghayeb@ph iut ac ir Date of Submission 2014 18 01 Department of Physics Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Dr Mehdi Ranjbar ranjbar@cc iut ac ir Abstract Tungsten oxide thin films with a suitable catalyst coating such as Pd or Pt are extensively used in fabrication of hydrogen optical sensors based on gasochromic property In these sensors the dissociation of H2 molecules on the catalyst surface and subsequent injection of proton electron into WO3 structure leads to optical alteration of WO3 layer The efficiency and durability of Pd WO3 sensors directly depend on the number of catalyst atoms However the adsorption of contaminated species like CO on the catalyst surface known as catalyst poisoning decreases the number of available sites for hydrogen dissociation resulting in destructive effects on gasochromic response On the other hand anatase titanium oxide is a capable semiconductor to break down the surface contaminations due to its photocatalytic property Therefore fabricating of TiO2 WO3 thin films may be a new approach to eliminate catalyst poisoning in hydrogen optical sensors The required temperature for anatase TiO2 formation is 400 600 C which in turn causes WO3 crystallization hence poor gasochromic response So modern laser annealing technique was utilized in order to form anatase TiO2 In this regared pulsed laser deposited TiO2 WO3 thin films were exposed to single pulse of excimer laser with different energies Our findings show that anatase TiO2 structure forms at 110 mj energy Increasing laser energy leads to crystallization of monoclinic WO3 Furthermore morphology and elements distribution in our samples change after laser irradiation Laser annealing reduces optical transmittance and band gap of TiO2 WO3 thin films too Water contact angle measurments confirm enhanced hydrophilicity after laser treatment Moreover laser irradiated samples at 110 mj and 170 mj have the best photocatalytic and gasochromic activities respectively Keywords Tungsten oxide Titanium oxide Pulsed laser deposition Gasochromic Catalyst poisoning Photocatalyst Laser annealing PDF created with pdfFactory trial version www pdffactory com

مهدي رنجبر

هادي سلامتي

اسماعيل عبدالحسيني سارسري، عليرضا علافچيان