Papers by Kandasamy Ramamurthi
Journal of Materials Science: Materials in Electronics, 2017
fluorescence peak observed at ~327 nm. Raman studies of the samples obtained from Experiment 1 an... more fluorescence peak observed at ~327 nm. Raman studies of the samples obtained from Experiment 1 and Experiment 2 showed a slight shift in the vibrational frequency. I-V studies carried out to investigate the electrical properties of the SnO 2 thin film formed by simple drop casting method revealed better ohmic contact and its suitability for gas sensing applications.
Ceramics International, 2016
In this work, influence of cetyltrimethylammonium bromide (CTAB) cationic surfactant of various c... more In this work, influence of cetyltrimethylammonium bromide (CTAB) cationic surfactant of various concentrations on the structural, morphological, dielectric and magnetic properties of cobalt ferrite (CoFe 2 O 4) nanoparticles, prepared by co-precipitation method, is reported. Powder X-ray diffraction, Fourier transform infrared and Raman spectral analyses confirmed the formation of cubic spinel structure of CoFe 2 O 4 nanoparticles. Transmission electron microscopy measurement revealed that the addition of CTAB cationic surfactant helps to control the size of CoFe 2 O 4 nanoparticles. Dielectric properties of CoFe 2 O 4 nanoparticles were enhanced by the addition of CTAB concentrations. Saturation magnetization (M s), coercivity (H c) and retentivity (M r) of CoFe 2 O 4 were significantly enhanced due to addition of CTAB in the synthesis process of CoFe 2 O 4 nanoparticles. Hence, the present results imply that the addition of CTAB cationic surfactant in the synthesis process controls the size of CoFe 2 O 4 nanoparticles and thus considerably influences the dielectric and magnetic properties of CoFe 2 O 4 .
Vanadium pentoxide (V 2 O 5) thin films were deposited by spray pyrolysis technique. Precursor so... more Vanadium pentoxide (V 2 O 5) thin films were deposited by spray pyrolysis technique. Precursor solution was prepared in two ways:(i) ammonium meta-vanadate (AMV) was dissolved in distilled water to prepare 0.1 M precursor solution; (ii) required amount of AMV was taken in a beaker and a few ml of concentrated nitric acid was added to it, which was then heated and maintained at 60 º C for 10 minutes. After naturally cooling the solution to the room temperature, required amount of distilled water was added to this to prepare 0.1 M aqueous solution. Fluorine doped vanadium oxide films were prepared adding ammonium fluoride of 5 wt. % and 15 wt. % in separate solution. These precursor solutions were used to deposit V 2 O 5 and fluorine doped V 2 O 5 films on the microslide glass substrate at 400°C. X-ray diffraction results show that the deposited films are in the mixed phase of V 2 O 5 and VO 2 .Increasing the concentration of ammonium fluoride in the precursor solution suppresses the ...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2010
... [7] PM Rateesh Kumar, C. Sudha Karthia, KP Vijayakumar, F. Singh, DK Avasthi, T. Abe, Y. Kash... more ... [7] PM Rateesh Kumar, C. Sudha Karthia, KP Vijayakumar, F. Singh, DK Avasthi, T. Abe, Y. Kashiwaba, GS Okram and S. Kumar, J. Appl. Phys. 97 (2005), p. 013509. [8] RL Fleischer, PB Price and RM Walker, J. Appl. Phys. 36 (1965), p. 3645. ...
Pure zinc oxide (ZnO) and Molybdenum doped zinc oxide (Mo:ZnO) thin films were deposited at 673K ... more Pure zinc oxide (ZnO) and Molybdenum doped zinc oxide (Mo:ZnO) thin films were deposited at 673K on micro slide glass substrates using spray pyrolysis technique. Deposited thin films are characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and UV-Visible Spectroscopy techniques. X-ray diffraction analysis of the ZnO films confirm the formation of hexagonal wurtzite crystal system and the preferred growth orientation is along (002) plane for pure and Mo doped (0.25 wt.%, 0.75 wt.% and 1 wt.%) ZnO films. For the 0.5 wt.% Mo:ZnO thin film, the (101) peak becomes prominent. The XRD intensity of the (002) peak decreases with increasing Mo doping concentration for 0.25 wt.% and 0.5wt.% then the intensity of (002) plane increases for 0.75 wt.% and 1 wt.% of Mo doping. Lattice parameter, dislocation density and strain were evaluated for the pure and Mo:ZnO thin films. Scanning Electron microscope images show nearly uniform distribution ...
Arabian Journal of Chemistry, 2017
Nonlinear optical material, 4-chloro-4 0 methoxy benzylideneaniline (CMOBA) was synthesized and s... more Nonlinear optical material, 4-chloro-4 0 methoxy benzylideneaniline (CMOBA) was synthesized and single crystal of CMOBA was grown by slow evaporation method. Functional groups of CMOBA were identified using the Fourier transform infrared spectral analysis and the molecular structure was confirmed by 1 H and 13 C NMR spectral analyses. Grown crystal was subjected to single crystal X-ray diffraction analysis to obtain unit cell parameters. UV-Vis-NIR optical study revealed that the UV cut off occurs at the wavelength of about 390 nm and the crystal is transparent in the wavelength range of 400-1100 nm. Second harmonic generation efficiency of the powdered CMOBA is about 3.7 times that of potassium dihydrogen orthophosphate. By using open aperture Z-scan (Nd:YAG, 532 nm, 5 ns) the measured effective two-photon absorption coefficient b was 3 • 10 À12 m/W. The melting point of the material is $125°C. The dielectric constant and dielectric loss were estimated for various frequencies at different temperatures.
Journal of Magnetism and Magnetic Materials, 2014
ABSTRACT Magnetic nanoparticles of chromium substituted cobalt ferrite (CoFe2−xCrxO4) were prepar... more ABSTRACT Magnetic nanoparticles of chromium substituted cobalt ferrite (CoFe2−xCrxO4) were prepared by the co-precipitation method for different concentrations (x=0.0, 0.1, 0.2 and 0.3) of chromium (Cr) and were annealed at 600 °C for 3 h. Formation of single phase cubic spinel structure was confirmed by X-ray diffraction analysis and the average crystallite size was in the range of 15–23 nm. Studies on the energy dispersive spectroscopy confirm the presence of Cr in Cr substituted CoFe2O4 nanoparticles. Transmission electron microscopy observations revealed that CoFe2O4 and Cr substituted CoFe2O4 nanoparticles are uniformly distributed and not highly agglomerated. Dielectric properties such as dielectric constant (ε′) and dielectric loss (εʺ) of prepared nanoparticles were investigated as a function of frequency and temperature. The dielectric study reveals that dielectric constant and dielectric loss are higher for Cr substituted CoFe2O4 than the corresponding value of pure CoFe2O4 nanoparticles. Studies on magnetic properties revealed that the saturation magnetization of samples decreases with increasing Cr concentration and lies in the range of 69.67–42.71 emu/g for the prepared samples. Strong red emission and weak blue and UV emissions are observed from the fluorescence spectral analysis of the prepared pure and Cr substituted CoFe2O4 nanoparticles.
CrystEngComm, 2013
ABSTRACT The organic nonlinear optical material of 4-bromo-4′-nitrobenzylidene aniline (BNBA, C13... more ABSTRACT The organic nonlinear optical material of 4-bromo-4′-nitrobenzylidene aniline (BNBA, C13H9BrN2O2), a new derivative of benzylideneaniline family, was synthesized and purified by repeated recrystallization. Single crystals of BNBA were grown in acetone solvent by slow evaporation at room temperature. Its (3+1)-dimensional incommensurately modulated structure was elucidated from single crystal X-ray diffraction data obtained at 173 K. The non-centrosymmetric structure was solved and refined in the monoclinic superspace group A2(α0γ)0; the unit cell parameters are a = 10.5217(10) Å, b = 16.2535(16) Å, c = 7.4403(7) Å, β = 110.709(7)°, modulation vector q = 0.0658(1)a*–0.2658(1)c*. At 290 K, the structure is partially disordered, however, the local structure of domains is identical to that at 173 K. The 1H and 13C NMR and Fourier Transform Infrared and FT-Raman spectroscopic studies confirmed the molecular structure. The Kurtz powder second-harmonic generation (SHG) test reveals that the SHG efficiency of BNBA is about 9.4 times higher than that of potassium dihydrogen phosphate. According to the thermogravimetric, differential thermal and differential scanning calorimetric analyses, BNBA is a stable phase starting from room temperature and up to the melting point, 436 K. The optical nonlinearity of BNBA was investigated at 532 nm using 5 ns laser pulses, employing the open aperture Z-scan technique.
The European Physical Journal Applied Physics, 2013
We used a homemade spray pyrolysis technique described below to prepare Prussian blue (PB) electr... more We used a homemade spray pyrolysis technique described below to prepare Prussian blue (PB) electrochromic (EC) thin films as a new approach, that will facilitate the doping process of Prussian blue by another salt to alter its electrochromic properties. It can be deposited on conductive and nonconductive substrates, which is difficult by electrodeposition method. To evaluate the new approach we prepared a sample with electrodeposition technique (EDS) with the same procedures as literature to make a comparison with spray pyrolysis sample (SPS). The optical, structure, morphology and electrochemical properties of these films were studied by UV-visible spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry(CV) and chronoamperometry traces (CA), respectively. The measurements reveal that SPS has more stability, excellent reversibility, and homogeneity during cycling than EDS. The coloration efficiency (η) of SPS was 124.3 cm 2 /C while it was 47 cm 2 /C for EDS prepared from the same precursor materials and on the same substrate.
Crystal Research and Technology, 2003
Optical properties of spray deposited antimony (Sb) doped tin oxide (SnO 2) thin films, prepared ... more Optical properties of spray deposited antimony (Sb) doped tin oxide (SnO 2) thin films, prepared from SnCl 2 precursor, have been studied as a function of antimony doping concentration. The doping concentration was varied from 0-4 wt. % of Sb. All the films were deposited on microscope glass slides at the optimized substrate temperature of 400° C. The films are polycrystalline in nature with tetragonal crystal structure. The doped films are degenerate and n-type conducting. The sheet resistance of tin oxide films was found to decrease from 38.22 Ω/ for undoped films to 2.17 Ω/ for antimony doped films. The lowest sheet resistance was achieved for 2 wt. % of Sb doping. To the best of our knowledge, this sheet resistance value is the lowest reported so far, for Sb doped films prepared from SnCl 2 precursor. The transmittance and reflectance spectra for the as-deposited films were recorded in the wavelength range of 300 to 2500 nm. The transmittance of the films was observed to increase from 42 % to 55 % (at 800 nm) on initial addition of Sb and then it is decreased for higher level of antimony doping. This paper investigates the variation of optical and electrical properties of the as-deposited films with Sb doping.
… Section C: Crystal …, 2002
... G. Vasuki, a S. Thamotharan, a V. Parthasarathi, a * K. Ramamurthi, a S. Dubey b and DP Jinda... more ... G. Vasuki, a S. Thamotharan, a V. Parthasarathi, a * K. Ramamurthi, a S. Dubey b and DP Jindal b. ... Acta Cryst. E58, o355-o356.] ; Vasuki, Thamotharan et al., 2002 [Vasuki, G., Thamotharan, S., Parthasarathi, V., Ramamurthi, K., Dubey, S. & Jindal, DP (2002). E58, o753-o755.] ). ...
Acta Crystallographica Section E Crystallographic Communications
In the title salt, {[Li(C2H5NO2)2]ClO4} n , the Li+ cation is coordinated by four carboxylate oxy... more In the title salt, {[Li(C2H5NO2)2]ClO4} n , the Li+ cation is coordinated by four carboxylate oxygen atoms of the glycine molecules with a distorted tetrahedral geometry. The glycine exists in a zwitterionic form with protonated amino and deprotonated carboxylate groups. In the crystalline state, the title salt is primarily stabilized by intermolecular N—H...O and Cα—H...O interactions which interconnect various units. Hirshfeld surface analysis indicates that the intermolecular H...O/O...H interactions are the most important contributors to the crystal packing.
Journal of Materials Science: Materials in Electronics
ABSTRACT Transparent conducting CdO thin films were deposited on to glass substrates by spray pyr... more ABSTRACT Transparent conducting CdO thin films were deposited on to glass substrates by spray pyrolysis technique. The depositions were carried out at different substrate temperatures with varying film thickness. The effects of substrate temperature on structural, optical and electrical properties of CdO thin films were systematically studied. The CdO films were polycrystalline in nature with cubic crystal structure showing preferential orientation along (111) direction. Wettability results confirmed that the hydrophobic character of CdO thin film is enhanced with increase in substrate temperatures. The average transmittance is about 80 %, thus the films are transparent in the visible region. The optical band gap value of the CdO films increased from 2.24 to 2.34 eV with increase in the substrate temperature from 200 to 350 °C. Surface morphology studies reveal that the grain size and roughness of the films are increased with increase in the substrate temperature. The minimum value of electrical resistivity of the films is 1.40 × 10−3 Ω cm obtained at 350 °C. The maximum ethanol sensitivity of 33.45 % is observed for the substrate temperature of 300 °C. Thus the results authenticate that the substrate temperature influences the structural, optical, electrical and sensing properties of the deposited films.
physica status solidi (a)
Gallium-doped zinc oxide (GZO) transparent conducting thin films were prepared by a cost-effectiv... more Gallium-doped zinc oxide (GZO) transparent conducting thin films were prepared by a cost-effective spray-pyrolysis method on glass substrates at 400 8C for various concentration of gallium (0-5 at.%) in the spray solution. Electrical, optical, and structural properties of as-deposited and annealed GZO films were investigated using Hall measurement, optical transmission, X-ray diffraction, and atomic force microscopy. As-prepared and vacuum annealed GZO films at 400 8C are preferentially orientated along the (002) crystallographic direction and annealing has enhanced the crystallinity of the films. A vacuum-annealed GZO film (3 at.%) acquired the lowest resistivity of 6.5 Â 10 À3 V cm with Hall mobility and carrier concentration of 18 cm 2 /V s and 5.4 Â 10 19 cm À3 , respectively. The transmittance of GZO film for 1 at.% is $84% in the visible region (400-800 nm) and it is markedly increased to $92% with the transmission edge shift towards the shorter-wavelength side on annealing. However, neither doping nor vacuum annealing of ZnO films modify the near band edge (3.26 eV) of the film appreciably. Ga doping is found to compensate the radiative oxygen vacancy levels and thus quench the green luminescence at 2.8 eV.
Acta crystallographica. Section E, Crystallographic communications, 2016
The title mol-ecular salt, C9H12NO4(+)·Cl(-)·C9H11NO4, is isotypic with that of the bromide count... more The title mol-ecular salt, C9H12NO4(+)·Cl(-)·C9H11NO4, is isotypic with that of the bromide counterpart [Kathiravan et al. (2016 ▸). Acta Cryst. E72, 1544-1548]. The title salt is a second monoclinic polymorph of the l-dopa HCl structure reported earlier in the monoclinic space group P21 [Jandacek & Earle (1971 ▸). Acta Cryst. B27, 841-845; Mostad & Rømming (1974 ▸). Acta Chemica Scand. B28, 1161-1168]. In the title compound, monoclinic space group I2, one of the dopa mol-ecules has a positive charge with a protonated α-amino group and the α-carb-oxy-lic acid group uncharged, while the second dopa mol-ecule has a neutral charge, the α-amino group is protonated and the α-carb-oxy-lic acid is deprotonated. In the previously reported form, a single dopa mol-ecule is observed in which the α-amino group is protonated and the α-carb-oxy-lic acid group is uncharged. The invariant and variations of various types of inter-molecular inter-actions present in these two forms of dopa HCl structu...
Acta Crystallographica Section E Crystallographic Communications, 2015
In the title coordination polymer, {[Sr(C5H9NO2)(H2O)4]Br2}n, the proline molecule exists in a zw... more In the title coordination polymer, {[Sr(C5H9NO2)(H2O)4]Br2}n, the proline molecule exists in a zwitterionic form with one of the ring C atoms disordered over two sites [site-occupancy factors = 0.57 (6):0.43 (6)]. The SrIIion is nine-coordinated by six water O atoms, two monodentate and two μ2-bridging, and three carboxylate O atoms of the proline ligands, with two bridging [Sr—O range = 2.524 (4)–2.800 (5) Å]. In the crystal, there is no direct interaction between the proline molecules. However, the proline and water molecules associate with the bromide counter-anions through a number of intermolecular O—H...Br and N—H...Br hydrogen-bonding interactions, giving a three-dimensional supramolecular structure.
Acta Crystallographica Section E Structure Reports Online
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Papers by Kandasamy Ramamurthi