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    Effect of thermal annealing on the structure of LiCoO2 powders prepared by co-precipitation method
    (2021-12-01)
    Khejonrak, Awadol
    ;
    Chanlek, Narong
    ;
    Sukkha, Usa
    ;
    Triamnak, Narit
    ;
    Chirawatkul, Prae
    Lithium cobalt oxide (LiCoO<inf>2</inf>) powder was prepared by co-precipitation method and annealed at different temperatures of between 300 and 700 °C. The effect of annealing temperature and effect washing process with deionized water on the crystal structures of the prepared LiCoO<inf>2</inf> powders were thoroughly studied by Synchrotron powder X-Ray Diffraction (Syn-XRD), X-ray Absorption Spectroscopy (XAS), Dispersive Raman Microscopy (Raman) techniques. The change in chemical composition as a function of annealing temperature was also investigated by X-ray Photoelectron Spectroscopy (XPS) technique. The crystal structural results identified the phase evolution of the prepared LiCoO<inf>2</inf> powders upon heat treatment. The formation of HT-LiCoO<inf>2</inf> phase was observed at annealing temperature as low as 300 °C.
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    Influences of calcination temperature on structural properties of MnFe2O4 nanopowders synthesized by co-precipitation method for reusable absorbent materials
    (2018-01-01)
    Junlabhut, P.
    ;
    Nuthongkum, P.
    ;
    Pechrapa, W.
    Manganese Ferrite (MnFe<inf>2</inf>O<inf>4</inf>) nanopowders have been synthesized via chemical co-precipitation method using metallic chlorides of manganese and iron as starting materials and sodium hydroxide (NaOH) was used as a precipitating agent. The obtained products were calcined at various temperatures of 400, 600, 800 and 1000°C. The structural properties and average crystallite size of after-calcined powders were investigated by X-ray diffraction (XRD) while morphologies of nanopowders were monitored by scanning electron microscope (SEM). The comparative study on chemical bonding of before-calcined and after-calcined powders have been carried out by Fourier transform infrared spectroscopy (FTIR). The co-precipitated MnFe<inf>2</inf>O<inf>4</inf> powders show good absorption of Methylene blue (MB) from aqueous solution and could be separated under a magnetic field. These results suggest that the co-precipitated MnFe<inf>2</inf>O<inf>4</inf> could be proposed as a reusable absorbent for removing MB with several cycles.
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    Effect of cobalt dopant on structural and optical properties of co-precipitated TiO2 nanopowders
    (2016-01-01)
    Junlabhut, Prasopporn
    ;
    Wattanawikkam, Chakkaphan
    ;
    Phoohinkong, Weerachon
    ;
    Mekprasart, Wanichaya
    ;
    Pecharapa, Wisanu
    The effects of cobalt (Co) addition on structural and optical properties of TiO<inf>2</inf> nanopowders have been investigated. A co-precipitation method was employed to synthesize TiO<inf>2</inf> nanoparticles with various Co additives from 0-10 mol% using tetrabutyl titanate and Cobalt (II) nitrate hexahydrate as starting precursors for Ti and Co source, respectively. The crystallinity of Co-doped TiO<inf>2</inf> nanopowders is heightened by calcination process. The crystal structure, phase formation and the corresponding functional groups of Co-doped TiO2 were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The scanning electron microscope (SEM) was taken to observe their morphologies. The chemical compositions of Co additive into TiO<inf>2</inf> matrix are confirmed by EDAX. Their optical properties were investigated by diffuse reflectance spectroscopy. Diffuse reflectance spectra of samples exhibit the increasing absorption in visible region with an increasing Co content. The overall characterization results indicated that the crystallinity and optical properties of TiO<inf>2</inf> nanoparticles are significantly affected by Co dopant.
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    Characterization of ZnO:Sn nanopowders synthesized by co-precipitation method
    (2014-01-01)
    Junlabhut, Prasopporn
    ;
    Mekprasart, Wanichaya
    ;
    Noonuruk, Russameeruk
    ;
    Chongsri, Krisana
    ;
    Pecharapa, Wisanu
    ZnO:Sn nanopowders were synthesized by co-precipitation method using zinc acetate dihydrate and tin (IV) chloride hexahydrate as a precursors. Co-precipitate of ZnO:Sn nanopowders with various Sn additive 0-50 %wt were obtained by calcination process at 500 °C. The corresponding functional groups and chemical bonding of the samples were investigated by Fourier Transform Infrared Spectroscopy (FTIR). The effects of Sn addition on structural and morphological properties of ZnO:Sn nanopowders have been investigated by X-ray diffraction (XRD), Raman Spectroscopy (Raman) and Scanning electron microscopy (SEM). The chemical bonding of Zn-O, Sn-O and Sn-OH in ZnO:Sn nanopowders were observed by FTIR results. The phase formation of this coumpound was observed with increasing Sn content with calcined at 500 °C. These results indicate that the crystallinity and structural of ZnO nanopowders are significantly affected by Sn dopant.
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    Study of antifungal activities of CuO/ZnO nanocomposites synthesized by co-precipitation method
    (2013-10-29)
    Phiwdang, Kankanit
    ;
    Phensaijai, Mongkol
    ;
    Pecharapa, Wisanu
    In this work, series of CuO/ZnO functional nanocomposites were synthesized through co-precipitation method using CuCl<inf>2</inf>·H<inf>2</inf>O and ZnCl<inf>2</inf> as starting materials with various molar ratio of copper:zinc, followed by annealing process at 600°C for 2 hours to obtain CuO/ZnO nanocomposites. The structures of the composites were analyzed using X-ray diffraction and field emission scanning electron microscopy. For XRD result, diffraction peaks of the composites reveal the well-crystalline characteristic indicating the mixture phase of CuO and ZnO. SEM results show different morphologies of CuO, ZnO and Cu-Zn oxide nanocomposites appearing in quasi spherical structure.The composites were used for antifungal activity via agar disk diffusion method. It is found that the composite with certain ratio of Cu:Zn exhibits superiority in partial inhibition of strain AspergillusflavusTrichoderma comparing to either pure CuO or ZnO. © (2013) Trans Tech Publications, Switzerland.
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    Structure properties of as-synthesized Cu-doped ZnO nanopowder synthesized by co-precipitation method
    (2013-01-01)
    Thaweesaeng, Napaporn
    ;
    Supankit, Sineenart
    ;
    Techidheera, Wicharn
    ;
    Pecharapa, Wisanu
    pure ZnO and Cu - doped ZnO nanopowders (1, 2, 3, 4 and 5 wt% Cu) were synthesized by coprecipitation method without further post-heat treatment. The as-synthesized powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Raman spectroscopy. The XRD results represented as-synthesized Cu-doped ZnO nanopowders in hexagonal wurtzite structure and SEM images demonstrated the shape and size of as-prepared samples. In addition, Raman spectra confirm space group of ZnO. All results indicated significant influence of Cu doping on relevant structural properties of ZnO. © 2013 The Authors.