Faculty Publications

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Subject: search.filters.subject.Cadmium compounds

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Now showing 1 - 10 of 25
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    Characterization of thin film Al/p-CdTe schottky diode
    (2008) Mahesha, M.G.; Kasturi, V.B.; Shivakumar, G.K.
    A study has been made on the behavior of Al/p-CdTe thin film junction grown by thermal evaporation method. I-V characteristics show that the Al makes Schottky contact with p-CdTe. The variation of junction capacitance with frequency and voltage has been studied to evaluate the barrier height. The activation energy and band gap have been estimated by studying variation of resistivity with temperature. Using all these data, band diagram of Al/p-CdTe has been proposed. © TÜB?TAK.
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    Characterization of p-CdTe/n-CdS hetero-junctions
    (2009) Mahesha, M.G.; Bangera, K.V.; Shivakumar, G.K.
    Nano-crystalline CdTe/CdS thin film hetero-junctions have been grown on glass substrate by thermal evaporation technique. The growth conditions to get stoichiometric compound films have been optimized. The grown hetero-junctions have been characterized for their I-V characteristics. Analysis of I-V characteristics has been made to investigate the current conduction mechanism in p-CdTe/n-CdS hetero-junction. The band gap energy of cadmium telluride and cadmium sulfide films have been computed from the study of variation of resistance with temperature. Based on the study, band diagram for p-CdTe/n-CdS hetero-junction has been proposed.
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    Studies on vacuum deposited p-ZnTe/n-CdTe heterojunction diodes
    (2011) Rao, K.G.; Bangera, K.V.; Shivakumar, G.K.
    The present paper reports the fabrication and detailed electrical characterization of p-ZnTe/n-CdTe heterojunction diodes prepared by vacuum deposition method. The possible conduction mechanisms of the heterojunction diode were determined by analyzing the I-V characteristics. The C-V characteristics of the heterojunction diodes were studied to determine the barrier height, carrier concentration and thickness of the depletion region in the heterojunction. A theoretical band diagram of the heterojunction was drawn based on Anderson's model. © 2010 Elsevier Ltd. All rights reserved.
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    Effect of chelaters on bioaccumulation of Cd (II), Cu (II), Cr (VI), Pb (II) and Zn (II) in Galerina vittiformis from soil
    (2013) Damodaran, D.; Shetty K, K.; Raj Mohan, B.
    Remediation of heavy metal contaminated soil and water streams are of great necessity as heavy metals are toxic and pose hazardous ecological impacts. Low cost mitigation measures like phytoremediation and mycoremediation are commonly employed. Mycoremediation using macro fungi (mushroom) have proven to provide effective tolerance using an efficient accumulation mechanism in removing heavy metals from soil. The current paper reports the heavy metal remediation potential of macro fungi on soil artificially contaminated with 50mgkg-1 of Cu (II), Cd (II), Cr (VI), Pb (II), and Zn (II) ions. Galerina vittiformis belonging to Strophariacea family was found to be effective in removing the heavy metal from the soil under study within 30 days. Both chemical and biological chelaters at 1, 5, and 10mmolkg-1 concentrations were found to increase the mycoremediation potential of the organism. This study showed that G. vittiformis are efficient in remediating heavy metal from contaminated soil and that their remediation potential can be enhanced by the addition of chelaters. © 2013 Elsevier Ltd.
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    Role of cadmium on corrosion resistance of Zn-Ni alloy coatings
    (Allerton Press Inc. journals@allertonpress.com, 2014) Rao, V.R.; Hegde, A.C.
    Cadmium (Cd) catalyzed Zn-Ni alloy plating has been accomplished galvanostatically on mild steel (MS) using gelatin and glycerol as additives. The effect of addition of Cd into Zn-Ni bath has been examined in terms of nickel (Ni) content and corrosion resistance of Zn-Ni-Cd ternary alloy coatings. The process and product of electrolysis under different concentrations of additives and Cd have been investigated by cyclic voltammetry (CV). The effects of current density (c.d.) on Ni content of the alloy have been studied by spectrophotometric method, supported by EDX analysis. The deposition has been carried out under different concentrations of Cd ranging from 0.004 to 0.1 M. The corrosion rates (CR) of Zn-Ni alloy coatings have been found to decrease drastically with addition of Cd. It has been also revealed that the CR of binary Zn-Ni alloy coatings decreased with the increase of Cd concentration only up to a certain optimal concentration, i.e., up to 0.02 M, and then remained unchanged. An effort to change the anomalous type of codeposition into normal one by changing the molar ratios of the metal ions, i.e. [Cd2+]/[Ni2+] as 0.01, 0.05 and 0.25 has remained futile. CV study demonstrated an important role of Cd in mutual depositions of Zn2+ and Ni2+ ions by its preferential adsorption, thus leading to the increased Ni content of the alloy. The bath composition and operating parameters have been optimized for deposition of bright and uniform Zn-Ni-Cd alloy coatings. Changes in the surface morphology and phase structure of Zn-Ni alloy coatings due to addition of Cd has been confirmed by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) study respectively. Experimental investigations so as to identify the role of Cd in codeposition Zn-Ni alloy coatings have been carried out and the results are discussed. © 2014 Allerton Press, Inc.
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    Cadmium (II) and nickel (II) biosorption by Bacillus laterosporus (MTCC 1628)
    (Taiwan Institute of Chemical Engineers, 2014) Kulkarni, R.; Shetty K, V.; Srinikethan, G.
    Biosorption of heavy metals is a promising technology that involves removal of toxic metals from industrial waste streams and natural waters. The study describes the sorption of cadmium (II) [Cd (II)] and nickel (II) [Ni (II)] by dead biomass of Bacillus laterosporus, MTCC 1628. The biosorption conditions for the removal of Cd (II) and Ni (II) were examined by studying the effect of pH, contact time, biosorbent dosage and initial metal ion concentration. Shake flask studies yielded adsorption equilibrium in almost 120. min, for both the metals. It was found from Langmuir model that the maximum adsorption capacity for Cd (II) and Ni (II) ions was 85.47. mg/g and 44.44. mg/g respectively. Kinetic evaluation of the experimental data showed that the biosorption process followed pseudo-second order kinetics. Thermodynamic analysis showed that biosorption is an endothermic process with ?. H° of 5.45. kJ/mol for Cd (II) biosorption and 24.33. kJ/mol for Ni (II) biosorption. The surface characteristics of B. laterosporus biomass before and after metal biosorption were analyzed by using scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDAX) to study the changes in surface morphology and elemental constitution of the adsorbent. B. laterosporus exhibited a higher and better potential biosorbent for the removal of Cd (II) as compared to Ni (II) from aqueous solution. © 2013 Taiwan Institute of Chemical Engineers.
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    Preparation and evaluation of heavy metal rejection properties of polysulfone/chitosan, polysulfone/N-succinyl chitosan and polysulfone/N-propylphosphonyl chitosan blend ultrafiltration membranes
    (Elsevier, 2014) Kumar, R.; Isloor, A.M.; A.F., A.F.
    Heavy metal rejection properties of chitosan based polysulfone/chitosan (PSf/CS), polysulfonef/N-succinyl chitosan (PSf/NSCS) and polysulfone/N-propylphosphonyl chitosan (PSf/NPPCS) ultrfiltration (UF) membranes were evaluated. The rejection of membranes towards the copper, cadmium and nickel ions was studied during ultrafiltration (UF) by polymer enhanced ultrafiltration (PEUF) processes. The flux change during the UF process and the effect of pH on the rejection were determined. The membrane recycling property was studied during PEUF process by filtering chelated CuSO4 solution. A maximum of 78% of Cu, 73% of Ni and 68% of Cd rejection for M-5 membrane, 75% of Cu, 71% of Ni and 66% of Cd rejection for M-8 membrane and 76% of Cu, 69% of Ni and 66% of Cd rejection for M-2 membrane with reasonably good flux was observed. Further improvement in heavy metal ion rejection was achieved by PEUF process. Membrane M-5 showed a maximum of 98%, 95% and 92% rejection for Cu, Ni and Cd respectively with steady state flux of 117L/m2h. An increase in membrane recycling property after the metal ion rejection was mainly attributed to the hydrophilicity of CS, NSCS and NPPCS. © 2014 Elsevier B.V.
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    Band gap engineering of mixed Cd(1?x)Zn(x)Se thin films
    (Elsevier Ltd, 2017) Santhosh, T.C.M.; Bangera, K.V.; Shivakumar, G.K.
    This paper deals with band gap engineering in CdZnSe thin films. This was achieved by adding different amounts of zinc selenide (ZnSe) to cadmium selenide (CdSe). The weight percentage of ZnSe (x) was varied from 0 to 1 in steps of 0.2. The films were prepared using thermal evaporation technique. The structural analysis was carried out using X-ray diffraction. Surface morphology and elemental composition of the grown films was investigated using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) respectively. As deposited cadmium selenide thin films were dark reddish in color, changes to lemon-yellow with increase in ZnSe concentration. Electrical transport studies have been carried out using two probe method. Resistivity of the mixed films increased with increase in ZnSe concentration and it shows semiconducting behavior. It is observed that activation energy for conduction increases from 0.39 eV to 0.85 eV with increase in ZnSe concentration. Optical properties of the films were analyzed from absorption and transmittance studies. It is observed that the optical band gap increases gradually from 1.67 eV to 2.60 eV as ‘x’ varied from 0 to 1. © 2017 Elsevier B.V.