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Anandan S.,Thiruvika Government Arts College | Muthukumaran S.,Hh The Rajahs College
Optical Materials | Year: 2013

Undoped and Yttrium doped ZnO nanopowders (Zn1- xYxO, 0 ≤ x ≤ 0.05) were prepared by sol-gel method and annealed at 500 C for 4 h under air atmosphere. The prepared nanopowders were characterized by powder X-ray diffraction, energy dispersive X-ray spectra, UV-Visible spectrophotometer and Fourier transform infrared spectroscopy. The EDS analysis confirmed the presence of Y in the ZnO system. Both atomic and weight percentages were nearly equal to their nominal stoichiometry within the experimental error. XRD measurement revealed the prepared nanoparticles have different microstructures without changing a hexagonal wurtzite structure. The calculated average crystallite size decreased from 26.1 to 23.2 nm for x = 0-0.02 then reached 24.1 nm for x = 0.05. The change in lattice parameters was demonstrated by the crystal size, bond length, micro-strain and the quantum confinement effect. The observed blue shift of energy gap from 3.36 eV (Y = 0) to 3. 76 eV (Y = 0.05) (ΔEg = 0.4 eV) revealed the substitution of Y3+ ions into ZnO lattice. The presence of functional groups and the chemical bonding are confirmed by FTIR spectra. The appreciable enhancement of PL intensity with slight blue shift in near band edge (NBE) emission from 396 to 387 nm and a red shift of green band (GB) emission from 513 to 527 nm with large reduction in intensity confirm the substitution of Y into the ZnO lattice. Y-doped ZnO is useful to tune the emission wavelength and hence is appreciable for the development of supersensitive UV detector. © 2013 Elsevier B.V. All rights reserved. Source


Sankar K.R.,Coromandel International Ltd | Venkatraman B.R.,Periyar Evr Government Arts College | Arivoli S.,Thiruvika Government Arts College
Research Journal of Pharmaceutical, Biological and Chemical Sciences | Year: 2013

Adsorption of MG dyes by the plaster of Paris was studied through the batch equilibrium techniques. The influence of contact time, initial concentration of dyes, pH and other ions were experimentally verified. The Freundlich and Langmuir models tested to describe the equilibrium isotherm reaction. The kinetics process of dyes adsorption on plaster of paris were described by applying pseudo second order, Elovich model and intra-particle diffusion and the kinetics data indicate that the adsorption follows pseudo second order kinetic surface adsorption. The equilibrium and thermodynamic parameters of the adsorption process were determined from the sorption behavior of pop and it results indicate that the adsorption of MG dye by pop is follows spontaneous nature and endothermic process. Source

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