Pudukkottai, India
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Kumaran S.M.,Hh The Rajahs College
Journal of Materials Science: Materials in Electronics | Year: 2012

ZnS:Cu thin films have been deposited on glass substrate by a simple neutral pH solution synthesis route and chemical bath deposition technique. The copper concentration was varied between 0 and 0.1 M%. The X-ray diffraction and scanning electron microscope studies show the average size of the nanoparticles are below 4 nm (Bohr diameter). The effect of film thickness on the optical and structural properties has been studied. The optical absorption studies show the band gap energy of ZnS:Cu films decreases from 3.68 to 3.43 eV as thickness varied from 318.3 to 334.1 nm. The structural estimation shows the variation in particle size from 2.67 to 3.14 nm with thickness. The insignificant change in band gap may be due to the increase in particle size and quantum size effect. © Springer Science+Business Media, LLC 2011.


Ashokkumar M.,Hh The Rajahs College | Muthukumaran S.,Hh The Rajahs College
Physics Procedia | Year: 2013

The chemical bath deposition (CBD) method has become very popular in recent years, especially for the thin film deposition, because it has less expensive than other thin film deposition methods which allows for the manufacture of relatively low cost devices. Cd0.9Zn0.1S thin films have been deposited on galass substrate with different deposition times from 30 min to 90 min by chemical bath deposition method. The optical and structural properties are investigated for different deposition times to get better insight into the microstructure of the material. The average grain size of the films is increased from 204 to 347 Å with increase in deposition time. The micro strain of the films is measured from XRD studies. The absorption of the films is increased and shifts the absorption peak to lower wavelength sides with deposition time. The energy gap of the films is increased with deposition times as observed in grain size. The micro strain, band gap and absorption enhancement with deposition time are due to the grain size enhancement with deposition time. © 2013 The Authors.


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.


Muthukumaran S.,Hh The Rajahs College | Ashok Kumar M.,Hh The Rajahs College
Materials Letters | Year: 2013

ZnS:Cu thin films were deposited on glass substrate using chemical bath by neutral pH solution synthesis route. Cu is varied between 0 and 0.1 M%. The XRD measurement shows hexagonal structure with the average crystalline size between 1.67 and 2.47 nm (below Bohr diameter). Energy dispersive X-ray spectrum reveals the presence of Cu in the ZnS lattice. The increase of lattice parameters, the reduction of particle size and a small shift in XRD peaks by Cu-doping reveals the substitution of Cu2+ ions into the ZnS lattice. The observed red shift of green emission from 506 to 519 nm in photoluminescence spectra confirms the presence of Cu2+ ions that are embedded in the ZnS matrix. © 2012 Elsevier B.V.


Valarselvan S.,Hh The Rajahs College | Manisankar P.,Alagappa University
Electrochimica Acta | Year: 2011

The electrocatalytic reduction of dioxygen by one mono and four dihydroxy derivatives of 9,10-anthraquinone (AQ) incorporated in polypyrrole (PPy) matrix on glassy carbon electrode has been investigated. The electrochemical behaviour of the modified electrodes was examined in various pH media and both the formal potential of anthraquinones and reduction potential of dioxygen exhibited pH dependence. AQ and PPy composite film showed excellent electrocatalytic performance for the reduction of O 2 to H 2O 2. pH 6.0 was chosen as the most suitable medium to study the electrocatalysis by comparing the peak potential of oxygen reduction and enhancement in peak current for oxygen reduction. The diffusion coefficient values of AQ at the modified electrodes and the number of electrons involved in AQ reduction were evaluated by chronoamperometric and chronocoulometric techniques, respectively. In addition, hydrodynamic voltammetric studies showed the involvement of two electrons in O 2 reduction. The mass specific activity of AQ used, the diffusion coefficient of oxygen and the heterogeneous rate constants for the oxygen reduction at the surface of modified electrodes were also determined by rotating disk voltammetry. © 2011 Elsevier Ltd. All rights reserved.


Muthu Kumaran S.,Hh The Rajahs College
Journal of Alloys and Compounds | Year: 2012

In situ ultrasonic measurements have been carried out in a 2024 Al-Cu-Mg alloy heat treated from 300 to 623 K. Different specimens have been prepared by (i) solution annealed at 766 K for 1 h, and (ii) water quenched then aged at 463 K for 10 h or 32 h. High temperature ultrasonic measurements from 300 to 623 K reveal the three transitions, (i) formation of GPB zone around 346 K, (ii) dissolution of GPB zones and S″ phase at 492 K, and (iii) the formation of semi-coherent S′ phase at 557 K which have been confirmed by DSC studies and SEM/TEM characterization. The different phase transformations and dissolutions at high temperature have been explained by the ultrasonic method and are compared to DSC and characterization with TEM. The first and second differential plot of the ultrasonic parameters with respect to temperature is identified as an effective tool in clearly identifying the fine scale precipitation/dissolution events. © 2012 Elsevier B.V. All rights reserved.


Kumaran S.M.,Hh The Rajahs College | Gopalakrishnan R.,P.A. College
Journal of Sol-Gel Science and Technology | Year: 2012

Ce doped ZnO nanoparticles (Zn 1-xCe xO, x = 0.0, 0.05 and 0.1) have been synthesized by sol-gel method at annealing temperature of 500 °C for 1 h under Ar atmosphere. The synthesized samples have been characterized by powder X-ray diffraction (XRD), energy dispersive X-ray studies, UV-Visible spectrophotometer and fourier transform infrared (FTIR) spectroscopy. The XRD measurements indicate that the prepared nanoparticles have a hexagonal wurtzite structure and CeO 2 crystallites. The calculated average crystalline varied from 21.97 to 15.62 nm with increase in Ce concentrations. The increase in lattice parameters reveals the substitution of Ce into ZnO lattice. The presence of functional groups and the chemical bonding is confirmed by FTIR spectra. PL spectra of the Zn 1-xCe xO system show that the shift in near band edge emission from 386 to 363 nm and a shift in blue band emission from 517 to 485 nm which confirms the substitution of Ce into the ZnO lattice. © Springer Science+Business Media, LLC 2012.


Muthukumaran S.,Hh The Rajahs College | Gopalakrishnan R.,Oxford Engineering College
Optical Materials | Year: 2012

Cu doped ZnO (Zn1-xCuxO, x = 0, 0.02, 0.04 and 0.06) nanopowders have been synthesized by co-precipitation method and annealed at 500°C for 2 h under Ar atmosphere. The synthesized samples have been characterized by powder X-ray diffraction, energy-dispersive analysis X-ray (EDAX) spectra, UV-Visible spectrophotometer and Fourier transform infrared (FTIR) spectroscopy. The XRD measurement reveals that the prepared nanoparticles have different microstructure without changing a hexagonal wurtzite structure. The calculated average crystalline size decreases from 22.24 to 15.93 nm for x = 0 to 0.04 then reaches 26.54 nm for x = 0.06 which is confirmed by SEM micrographs. The change in lattice parameters, micro-strain, a small shift and broadening in XRD peaks and the reduction in the energy gap from 3.49 to 3.43 eV reveals the substitution of Cu2+ ions into the ZnO lattice. Hydrogenation effect improves the crystal quality and optical properties. It is proposed that Cu doping concentration limit is below 6% (0.06) molar fraction which is supported by the detailed XRD analysis and the derived structural parameters. This Cu concentration limit was proposed as below 5% by previous studies. The presence of functional groups and the chemical bonding is confirmed by FTIR spectra. PL spectra of the Zn1-xCuxO system show that the shift in near band edge (NBE) UV emission from 398 to 403 nm and a shift in green band (GB) emission from 527 to 522 nm which confirms the substitution of Cu into the ZnO lattice. © 2012 Elsevier B.V. All rights reserved.


Muthukumaran S.,Hh The Rajahs College | Gopalakrishnan R.,Oxford Engineering College
Physica B: Condensed Matter | Year: 2012

Un-hydrogenated and hydrogenated Cu, Co co-doped ZnO (Zn 0.96-xCo 0.04Cu xO, x=0.03, 0.04 and 0.05) nanopowders have been synthesized by co-precipitation method. The synthesized samples have been characterized by powder X-ray diffraction, energy dispersive X-ray spectra, UV-Visible spectrophotometer and Fourier transform infrared spectroscopy. The calculated average crystalline size increases from 37.3 to 50.6 nm for un-hydrogenated samples from x=0.03 to 0.05 and it changes from 29.4 to 34.9 nm for hydrogenated samples. The change in lattice parameters, micro-strain, a small shift of X-ray diffraction peaks towards lower angles and reduction in energy gap reveal the substitution of Cu 2 ions into Zn-Co-O lattice. The hydrogenation effect reduces the particle size and induces the more uniform distribution of particles than the un-hydrogenated samples which is confirmed by SEM micrographs. Photoluminescence spectra of Zn 0.96-xCo 0.04Cu xO system shows that red shift in near band edge ultraviolet emission from 393 to 403 nm with suppressing intensity and a blue shift in green band emission from 537 to 529 nm with enhancing intensity confirms the substitution of Cu into the Zn-Co-O lattice. © 2012 Elsevier B.V. All rights reserved.


Muthukumaran S.,Hh The Rajahs College | Gopalakrishnan R.,P.A. College
Journal of Materials Science: Materials in Electronics | Year: 2012

Undoped and heavily Mn-doped with ZnO nano-particles (Zn 1-xMn xO, x = 0.0, 0.05, 0.1 and 0.2) annealed under Ar atmosphere have been synthesized by a sol-gel method. The structural properties and optical absorption of the prepared samples have been examined by powder X-ray diffraction, energy dispersive X-ray analysis, Fourier transform infrared (FTIR) spectroscopy and UV-visible spectropho-tometer. Hexagonal wurtzite structure of the samples is confirmed by the XRD spectra. The average crystalline size of the Zn 1-xMn xO nanoparticles has been calculated from X-ray line broadening and is decreased from 35.73 to 18.24 nm with increase in Mn concentrations from 0.0 to 0.2. The increase in lattice parameters indicates the substitution of Mn in ZnO lattice. SEM and TEM photographs indicated that the grain size of undoped ZnO is bigger than the Mn-doped ZnO which is due to the limitations of grain growth upon Mn doping. The presence of functional groups and the chemical bonding due to Mn doping is confirmed by FTIR spectra. PL spectra of the Zn 1-xMn xO system showed that the shift in near band edge emission at 390 nm and a blue band emission at 450-490 nm which confirms the substitution of Mn. © 2012 Springer Science+Business Media, LLC.

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