Arnab Sankar Bhattacharyya; Ritambhara Dash
Abstract
The rGO-ZnO composite was found promising improvement over the photocatalytic ability of pure ZnO and is useful for other Opto-chemical applications. ZnO/rGO composite was synthesized by the sol-gel method. The morphology of rGO caused better dispersion of the ZnO crystallites The reducing agent ammonia ...
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The rGO-ZnO composite was found promising improvement over the photocatalytic ability of pure ZnO and is useful for other Opto-chemical applications. ZnO/rGO composite was synthesized by the sol-gel method. The morphology of rGO caused better dispersion of the ZnO crystallites The reducing agent ammonia was varied in concentration during the synthesis. A reduction in the crystallization was observed for lower concentrations (0 – 1%) of ammonia which got stabilized in higher concentrations (>1%). The crystalline morphology showed variations from being close to amorphous to 38 nm. The average crystallite size was 15 nm. The rGO induced nonradiative phononic modes in the optical transition process when present in lower concentration but interestingly aided the crystallization process in a preferential crystallographic orientation which however got lowered in intensity for >2% ammonia concentration. The defect states formed in the rGO/ZnO composite in the form of oxygen vacancies, zinc interstitials, and vacancies caused a decrease in band gap due to indirect transitions. The role of ammonia in the performance of the composites was found to be significant
Raviraj M. Kulkarni; Ramesh S. Malladi; Manjunath S. Hanagadakar
Abstract
Photocatalytic degradation of textile dye derivative Methyl Orange (M.O) has been studied in aqueous medium using 2% copper doped zinc oxide (2% Cu-ZnO) nanoparticles under UV irradiation. Simple inexpensive chemical precipitation method was used for synthesis of pure and copper doped zinc oxide nanoparticles. ...
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Photocatalytic degradation of textile dye derivative Methyl Orange (M.O) has been studied in aqueous medium using 2% copper doped zinc oxide (2% Cu-ZnO) nanoparticles under UV irradiation. Simple inexpensive chemical precipitation method was used for synthesis of pure and copper doped zinc oxide nanoparticles. The prepared nanoparticles pure and copper doped zinc oxide was characterized by X-ray Diffraction Technique (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis. The prepared nanoparticles were hexagonal wurzite structure. Photocatalytic efficiency of 2% Cu-ZnO were evaluated by studying mineralization of methyl orange (M.O.) as a model compound. The M.O. kinetics degradation was investigated under different parameters such as pH of the medium, catalyst dosage, M.O concentration, intensity of light etc. In addition reusability aspects of nanoparticles where also studied, which reveals that reused nanoparticles exhibited same results as that of virgin particles. Copyright © 2018 VBRI Press.
Raviraj M. Kulkarni; Ramesh S. Malladi; Manjunath S. Hanagadakar
Abstract
Liquid Impregnation (LI) technique was developed to prepare 1% and 2% Ag doped Titania nanoparticles. The characterization of the prepared nanoparticles was achieved by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and Transmission Electron Microscopy ...
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Liquid Impregnation (LI) technique was developed to prepare 1% and 2% Ag doped Titania nanoparticles. The characterization of the prepared nanoparticles was achieved by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and Transmission Electron Microscopy (TEM). The crystallite size was obtained by Scherrer equation analysis of XRD main peak of doped and undoped nanoparticles. It was observed that crystallite size of bare TiO2 was 17.00 nm, whilst the crystallite size of 1% Ag doped titania and 2% Ag doped titania was 13.07 nm to 14.17 nm. TEM images ascertained that particle size of Ag-TiO2 nanoparticles were in the range 40-45 nm in length and 10-15 nm in width. The pH of the solution exerted a negative effect on photodegradation rate of sparfloxacin. The masking effect on the degradation of sparfloxacin was observed at higher catalyst dosages. The increase in UV intensity linearly enhanced the degradation rate of sparfloxacin and the influence of initial sparfloxacin concentration on the degradation rate was investigated and discussed. Copyright © 2018 VBRI Press.
P. Neelima; S. R. Murthy
Abstract
Microwave-hydrothermal (M-H) method had been employed to synthesize a series of Dy3+doped Mn-Zn ferrite Mn0.6Zn0.4Fe2–xDyxO4 (x=0, 0.01, 0.03, 0.05, 0.07, 0.09) nanopowders at 160°C/30 min. The prepared samples have been characterized by Fourier Transform Infrared Spectrometer. The grain size ...
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Microwave-hydrothermal (M-H) method had been employed to synthesize a series of Dy3+doped Mn-Zn ferrite Mn0.6Zn0.4Fe2–xDyxO4 (x=0, 0.01, 0.03, 0.05, 0.07, 0.09) nanopowders at 160°C/30 min. The prepared samples have been characterized by Fourier Transform Infrared Spectrometer. The grain size of sintered ferrites are in the range of 60-70 nm. Decrease in saturation magnetization and increase in coercivity were observed with an increase of Dy3+ concentration in Mn-Zn ferrites. The complex permeability and complex permittivity of the prepared samples were measured in the frequency range of 2–18 GHz using a using a vector network analyzer. It is observed that small variation of Dy3+ substitution in spinel ferrite tailored microwave absorbing parameters dramatically. The reflection loss (RL) increased with the Dy3+ content upto x ≤ 0.03. The sample with x=0.03 of thickness 2.3 mm showed minimum reflection loss of -20.5 dB with a bandwidth of 3.8 GHz. Thus the present materials exhibit good microwave absorption properties and hence can act as EMI suppressors. Copyright © 2018 VBRI Press.
Martin Wilhelm; Mikael Syväjärvi; Peter J. Wellmann
Abstract
Among the various SiC polytypes, cubic 3C‐SiC is much more difficult to grow in high crystalline quality than the commercially introduced hexagonal 6H‐SiC and 4H‐SiC counterparts. Besides some benefits of 3C‐SiC for transistor applications related to a greater electron mobility and a lower metal‐oxide‐semiconductor ...
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Among the various SiC polytypes, cubic 3C‐SiC is much more difficult to grow in high crystalline quality than the commercially introduced hexagonal 6H‐SiC and 4H‐SiC counterparts. Besides some benefits of 3C‐SiC for transistor applications related to a greater electron mobility and a lower metal‐oxide‐semiconductor interface trap density compared to 4H‐SiC, new potential optoelectronic applications have been introduced very recently. Boron doped 3C‐SiC may act as an ideal candidate for an intermediate band (IB) solar cell material. Aluminum doped p‐type 3C‐SiC could lead to the development of efficient optoelectrochemical water splitting cells. Finally, 3C‐SiC with its various intrinsic point defects has been considered as a suitable candidate for future spintronic‐applications. All these applications will critically depend on further understanding defect behaviour on atomic level. In our study we investigated free standing n‐type and p‐type 3C‐SiC material grown in our lab. Temperature dependent photoluminescence measurements revealed the presence of carbon vacancy related VC and VC-CSi defect transitions in the p‐type materials but not in the n‐type materials. This observation present in as grown 3C-SiC is believed to have significant impact on the optoelectronic applications. Copyright © 2017 VBRI Press.