Photonic crystals in biology

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Poster Session, Tuesday, June 15 Theme A1 - B702 Synthesis and characte rization of TiO 2 nanotubes filed with NiFe 2 O 4 nanocrystals A.A. Fargali 1 , M . H. Khedr 1 , M. Bahagat 2 * and A. F. Moustafa 1 1 Chemistry Dep. Fac. of Sci. Beni-Sueif Univ., Beni-Sueif , Egypt 2 CMRDI, Egypt Abstrac t-TiO 2 NTs is the most attractive catalyst in many fields of application, as semiconductors, photocatalyst, gas sensor. There are many method for preparation of TiO 2 NTs, anodization, Templates assistance, and thermal method. In this work TiO x nanotubes was prepared from anatase phase of TiO 2 powder with crystal size 90 nm via hydrothermal treatment in 10M NaOH at different time and temperature flowed by ion exchange reaction. The samples prepared at higher temperature and longer reaction time shows high quantity and good c rystallinity than those prepared at lower temperature and shorter reaction time. TiO x Nanotubes was treated in oxygen at 500 o C for 2 h to obtain anatase phase of TiO 2 nanot ube s (TiO 2 NTs). The filling process of TiO 2 NTs with NiFe 2 O 4 occurs by immersing TiO 2 NTs in mixed solution of iron nitrate and nickel nitrate with adjusted molar ratio. The percentage of filling process depends strongly on the concentration of mixed solution and the immersing time. The empty and filled TiO 2 NTs was characterized using XRD, TEM, and SEM. The filled NTs was reduced at different temperatures to obtain Ni-Fe nanoalloy inside NTs, we found that the optimum temperature for complete reduction of filled NTs is 600 o C, which produced Ni-Fe nanoa lloy and saving geometry of nanotube s. The photocatalytic activity of as prepared, heated, empty, filled and reduced NTs was studied for the degradation of Brobopyrogallol red (Bb red) and adsorption of some heavy metals. *Corresponding author: m_bahgat70@yahoo.com 6th Nanoscience and Nanotechnology Conference, zmir, 2010 369
Poster Session, Tuesday, June 15 Theme A1 - B702 Structural and electrical properties of spray deposited pure and Sb doped tin oxide * Güven Turgut, Demet Tatar, Serdar Aydın, Erdal Sönmez and Bahattin Düzgün K. K. Education Faculty, Department of Physics, Ataturk University, Erzurum 25240, Turkey Abstract— Pure and 2wt. % Sb doped tin oxide (SnO 2 :Sb) thin films were prepared by spray pyrolysis onto glass substrates at 420 0 C. X-ray diffraction (XRD) analysis showed that all films are polycrystalline and Sb doping increased crystallinity. The films are prefentially oriented along the (110) direction. Atomic force microscopy (AFM) studies showed that roughness (RMS) of 22.52 nm for undoped films has been slightly reduced to 15.56 nm on Sb doping films. Hall effect studies have been performed on SnO 2 (TO) and SnO 2 :Sb(ATO) films coated on glass substrates.The electrical study reveals that the films are degenerate and exhibit n-type electrical conductivityand also Sb doping increased carrier concentrarion(n), decreased sheet resistance(Rs) and resistivity(ρ). Among transparent and conducting oxides (TCOs), tin oxide (TO) is widely used in solar cells, display devices, hybrid microelectronics, stable resistors, touch-sensitive switches digital displays [1], electro-chromic displays and gas sensors [2] etc. due to theirs low electrical resistivity, high optical transmittance in visible region, high optical reflectance in infrared region, chemically inert and mechanically hard [3]. Many researchers focused on doping TO, because electrical, structural and optical properties of TO can be changed by doping with F or Sb [1-8]. In this study, pure and 2 wt.% Sb doped SnO 2 thin films onto glass substrates at 420 ο C were deposited by spray pyrolysis technique. The spray pyrolysis technique is an attractive method to obtain thin films because of its simple and inexpensive experimental arrangement [9], ease of adding doping materials, reproducibility [3], high growth rate and mass production capability for uniform large area coatings [7]. We investigated structural, morphological and electrical properties of pure and Sb doped SnO 2 thin films. The structural characterization of the films was carried out by X-ray diffraction (XRD) measurements using a Rigaku D/Max-IIIC diffractometer (λ=1.5418Å for CuKα radiation) at 30 kV, 10 mA. Surface morphology was examined by atomic force microscopy (AFM, which was produced by Nanomagnetics- Instrument). The electrical measurements were carried out by Hall measurements in van der Pauw configuration. (a) (b) Fig. 2. AFM images of (a) pure tin oxide (SnO 2 ) and (b) 2wt.% Sb doped tin oxide (SnO 2 :Sb) The AFM study reveals nanostructural growth of the film. AFM analysis showed that, Sb doping decreased RMS value for TO, thus Sb doping improved the film morphologies. The negative sign of Hall coefficient confirmed that the films are n-type. As seen from Table 1, Sb doping decreased sheet resistance (Rs), resistivity(ρ) and increased carrier concentration(n) and Hall mobility(μ). Table 1. Electrical properties of SnO 2 and 2wt.% Sb doped tin oxide ( SnO 2 :Sb) Sample Rs (Ωcm -2 ) ρ (x10 -4 Ωcm) n (x10 18 cm -3 ) μ (cm 2 /V s) SnO 2 728,3 64,1 0,215 452 SnO 2 :Sb 114,9 6,4 1,7 560 In summary, undoped and Sb doped SnO 2 thin films have successfully been via a simple and cost-effective spray pyrolysis technique. Structural analyses showed that the Sb doping increased crystallinity and improved surface morphology. Electrical studies revealed that Sb doping decreased resistivity of tin oxide film and increased carrier concentration. Fig. 1. XRD patterns of SnO 2 (TO) and SnO 2 :Sb (ATO) XRD images showed that the films are polycrystalline and are prefentially oriented along (110) direction. Other peaks observed are (101), (200) and (211). Further, the crystallinity was seen to be increasing, since peak intensities increased as Sb doping. *Corresponding author: guventurgut@atauni.edu.tr [1] K. Ravichandran, et al. Journal of Ovonic Research. 5, 93-69 (2009). [2] E. Elangovan et al. Journal of Crystal Growth. 276, 215-221 (2005). [3] B. Thangaraju, Thin Solid Films. 402, 71-78 (2002). [4] S. Lee, B. Park, Thin Solid Films. 510, 154-158 (2006). [5] K. Ravichandran, P. Philominethan, Materials Letters. 62, 2980-2983 (2008). [6] E. Elangovan, K. Ramamurthi, Applied Surface Science. 249, 183-196 (2005). [7] K. Ravichandran, G. Muruganantham, Physica B. 404, 4299-4302 (2009). [8] E. Elangovan, K. Ramamurthi, Cryst. Res. Technol. 38, 779-784 (2003). [9] R.R. Kasar et al. Physica B. 403, 3724-3729 (2008). 6th Nanoscience and Nanotechnology Conference, zmir, 2010 370
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