Browsing by Author "Maaza, M"
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Item Synthesis, characterization and ab initio study of WO3 nanocubes with peculiar electrochemical properties(Springer, 2021) Bashir, A. K.H; Morad, R; Nwanya, A. C; Akbari, M; Sackey, J; Kaviyarasu, K; Madiba, I. G; Ezema, F. I; Maaza, MSimple sol–gel method has been exploited to deposit Sn-doped TiO2 thin flms on glass substrates. The resultant coatings were characterized by X-ray difraction (XRD), UV–visible techniques (UV–Vis), Fourier transform infrared spectroscopy (FTIR), and photoluminescence analysis (PL). The XRD pattern reveals an increase in crystallite size of the prepared samples with the increasing doping concentration. A decrease in doping concentrating resulted in the decrease in bandgap values. The diferent chemical bonds on these flms were identifed from their FTIR spectra. The photoluminescence analysis shows an increase in the emission peak intensity with increasing dopant concentration, and this can be attributed to the efect created due to surface states. The prepared samples were tested as antibacterial agent toward both Gram-positive and Gram-negative bacteria like S.aureus (Staphylococcus aureus) and E.coli (Escherichia coli), respectively. The size of the inhibition zones indicates that the sample shows maximum inhibitory property toward E.coli when compared to S.aureus.Item Towards stimuli-responsive functional nanocomposites: Smart tunable plasmonic nanostructures au-v02(University of the Western Cape, 2010) Kama Kama, Jean Bosco; Maaza, M; Knoesen, DThe fascinating optical properties of metallic nanostructures, dominated by collective oscillations of free electrons known as plasmons, open new opportunities for the development of devices fabrication based on noble metal nanoparticle composite materials. This thesis demonstrates a low-cost and versatile technique to produce stimuli-responsive ultrafast plasmonic nanostructures with reversible tunable optical properties. Albeit challenging, further control using thermal external stimuli to tune the local environment of gold nanoparticles embedded in V02 host matrix would be ideal for the design of responsive functional nanocomposites. We prepared Au-V02 nanocomposite thin films by the inverted cylindrical reactive magnetron sputtering (ICMS) known as hollow cathode magnetron sputtering for the first time and report the reversible tuning of surface plasmon resonance of Au nanoparticles by only adjusting the external temperature stimuli. The structural, morphological, interfacial analysis and optical properties of the optimized nanostructures have been studied. ICMS has been attracting much attention for its enclosed geometry and its ability to deposit on large area, uniform coating of smart nanocomposites at high deposition rate. Before achieving the aforementioned goals, a systematic study and optimization process of V02 host matrix has been done by studying the influence of deposition parameters on the structural, morphological and optical switching properties of V02 thin films. A reversible thermal tunability of the optical/dielectric constants of V02 thin films by spectroscopic ellipsometry has been intensively also studied in order to bring more insights about the shift of the plasmon of gold nanoparticles imbedded in V02 host matrix.Item Towards stimuli-responsive functional nanocomposites: Smart tunable plasmonic nanostructures au-v02(University of the Western Cape, 2010) Kama Kama, Jean Bosco; Maaza, M; Knoesen, DThe fascinating optical properties of metallic nanostructures, dominated by collective oscillations of free electrons known as plasmons, open new opportunities for the development of devices fabrication based on noble metal nanoparticle composite materials. This thesis demonstrates a low-cost and versatile technique to produce stimuli-responsive ultrafast plasmonic nanostructures with reversible tunable optical properties. Albeit challenging, further control using thermal external stimuli to tune the local environment of gold nanoparticles embedded in V02 host matrix would be ideal for the design of responsive functional nanocomposites. We prepared Au-V02 nanocomposite thin films by the inverted cylindrical reactive magnetron sputtering (ICMS) known as hollow cathode magnetron sputtering for the first time and report the reversible tuning of surface plasmon resonance of Au nanoparticles by only adjusting the external temperature stimuli. The structural, morphological, interfacial analysis and optical properties of the optimized nanostructures have been studied. ICMS has been attracting much attention for its enclosed geometry and its ability to deposit on large area, uniform coating of smart nanocomposites at high deposition rate. Before achieving the aforementioned goals, a systematic study and optimization process of V02 host matrix has been done by studying the influence of deposition parameters on the structural, morphological and optical switching properties of V02 thin films. A reversible thermal tunability of the optical/dielectric constants of V02 thin films by spectroscopic ellipsometry has been intensively also studied in order to bring more insights about the shift of the plasmon of gold nanoparticles imbedded in V02 host matrix.