S. Som; S. Dutta; Subrata Das; Mukesh Kumar Pandey; Ritesh Kumar Dubey; S. P. Lochab; S. K. Sharma
Abstract
Herein, a comparative study on the structural and luminescence properties of optimized Y2O3:Eu 3+ /Tb 3+ nanophosphor has been reported after 150 MeV Ni 7+ , 120 MeV Ag 9+ and 110 MeV Au 8+ ion beam irradiation at various fluences ranging from 1×10 11 to 1×10 13 ions/cm 2 . The X-ray diffraction ...
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Herein, a comparative study on the structural and luminescence properties of optimized Y2O3:Eu 3+ /Tb 3+ nanophosphor has been reported after 150 MeV Ni 7+ , 120 MeV Ag 9+ and 110 MeV Au 8+ ion beam irradiation at various fluences ranging from 1×10 11 to 1×10 13 ions/cm 2 . The X-ray diffraction results confirm the cubic phase in case of unirradiatedY 2 O 3 :Eu 3+ /Tb 3+ nanophosphor. The loss of crystallinity was observed after ion irradiation and Au ion is more effective to damage the crystal structure in these phosphors. The transmission electron microscopic results show the reduction of the particle size from 100 nm to 50, 30 and 20 nm after ion irradiation with the Ni 7+ , Ag 9+ and Au 8+ ions, respectively. Diffuse reflectance spectra show a blue shift in the absorption band owing to the increase in the band gap after ion irradiation. An increase in the photoluminescence intensity without any shift in the peak positions was observed with the increase in the ion fluence. The colour tunability was observed with ion irradiation as the colour coordinate varies from red to white chromaticity.
Ranjana S. Varma; D.C. Kothari; A.K. Mallik; A. Bhatnagar; D. Kanjilal; S. Santra; R.G. Thomas; R. Tewari; S. Neogy; G.K. Dey
Abstract
Silver ion exchanges on silicate glasses were carried out at different temperatures 320 °C, 400 °C, and 500 °C for 60 min. The exchanged glasses were either annealed at 500 °C for 60 min or swift heavy ion (SHI) irradiated using 120 MeV Ag 9+ ions at a fluence of 5 x 10 12 ions/cm 2 . ...
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Silver ion exchanges on silicate glasses were carried out at different temperatures 320 °C, 400 °C, and 500 °C for 60 min. The exchanged glasses were either annealed at 500 °C for 60 min or swift heavy ion (SHI) irradiated using 120 MeV Ag 9+ ions at a fluence of 5 x 10 12 ions/cm 2 . Silver nanoparticles were formed in the samples ion exchanged at 500 °C without any post-exchange treatments. Post-exchange annealing treatment resulted in silver nanoparticle formation for samples ion exchanged at temperature of 320 °C and 400 °C. Whereas post irradiation treatment for ion exchanged sample at 320 °C resulted in Ag4 nanocluster formation. After post-irradiation, the density of Ag nanoparticles increases for the sample ion exchanged at temperature of 500 °C. RBS was used to obtain silver depth profiles in the ion exchanged samples. Near surface accumulation of Ag atoms is observed in the RBS spectra for the samples prepared at high ion exchange temperature of 500 °C or SHI irradiated samples, in which Ag nanoparticle formation was also observed. UV-vis absorption spectroscopy and Transmission Electron Microscopy (TEM) were used to obtain signatures of nano-particles and to estimate their size. The ion exchanged glasses without nanoparticles were characterized for their possible use in multimode planar waveguides. The post-exchange treated glasses lost their waveguide property, but exhibited nonlinear optical property indicating their potential use for optical switching. Open aperture z-scan measurements for the sample prepared at high ion exchange temperature of 500 °C shows optical limiting behavior, whereas the samples prepared at low ion exchange temperature followed by annealing or irradiation show saturation behavior.
N.J. Shivaramu; B.N. Lakshminarasappa; K.R. Nagabhushana; Fouran Singh
Abstract
Nanocrystalline erbium doped yttrium oxide (Y2O3:Er 3+ ) was synthesized by the sol-gel technique using citric acid as complexing agent. The synthesized samples were characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM) techniques for phase-purity and microstructure. ...
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Nanocrystalline erbium doped yttrium oxide (Y2O3:Er 3+ ) was synthesized by the sol-gel technique using citric acid as complexing agent. The synthesized samples were characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM) techniques for phase-purity and microstructure. Er 3+ doped Y2O3 crystallizes in cubic phase with an average crystallite size of 24.3 nm. The pellets of Y2O3:Er 3+ were irradiated with 100 MeV swift Si 8+ ions with fluence in the range of 3×10 11 - 3×10 13 ions cm -2 . Three well resolved thermoluminescence (TL) glows with peaks at ~422, 525 and 620 K were observed in Er 3+ doped Y2O3 samples. It was observed that the TL intensity was found to increases with increasing Er 3+ concentration up to 0.4 mol% in Y2O3 and thereafter it decreases with further increase of Er 3+ concentration. Also, the intensity of low temperature TL glow peak (~422 K) increases with increasing ion fluence up to 1×10 12 ions cm -2 and decreases with further increase of ion fluences. The TL trap parameters were calculated by glow curve shape method and the deconvoluted glows were exhibit of second order kinetics.
T. Diana; D. C. Agarwal; P. K. Kulriya; S. K. Tripathi; H. Nandakumar Sarma
Abstract
100 MeV Ag ions have been used to study the swift heavy ion (SHI) induced modification in Te/Bi bilayer system. The samples were analysed using Rutherford backscattering spectroscopy (RBS), Atomic force microscopy (AFM) and X-ray diffractometer (XRD). The elemental depth study with RBS results show a ...
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100 MeV Ag ions have been used to study the swift heavy ion (SHI) induced modification in Te/Bi bilayer system. The samples were analysed using Rutherford backscattering spectroscopy (RBS), Atomic force microscopy (AFM) and X-ray diffractometer (XRD). The elemental depth study with RBS results show a strong mixing between the top Te layer and the underlying Bi layer on irradiation. Surface roughness as calculated by AFM is found to increase from 8 to 30 nm on irradiation for the fluence 3x10 13 ions/cm 2 . XRD results confirm the formation of Bi-Te alloy phases on mixing and are expected to be formed due to the interfacial reaction taking place within the molten ion tracks. Ion beam mixing has the potential to induce the formation Bi-Te alloy thin films which are the promising candidate for thermoelectric applications near room temperature.
Vinod Kumar; L. P. Purohit;Fouran Singh; R. G. Singh
Abstract
Swift heavy ion (SHI) induced modification in structural and optical properties of undoped and doped nanocrystalline (nc) ZnO films deposited by sol-gel method are investigated. These nanocrystalline films were irradiated by MeV ions of Au, Ag and Ni at various ion fluences. The structural properties ...
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Swift heavy ion (SHI) induced modification in structural and optical properties of undoped and doped nanocrystalline (nc) ZnO films deposited by sol-gel method are investigated. These nanocrystalline films were irradiated by MeV ions of Au, Ag and Ni at various ion fluences. The structural properties were studied using X-ray diffraction and it shows that the average crystallite size of ZnO films is observed to increase by the irradiation. The atomic force microscopy (AFM) study of films shows that the roughness of the films varies with increase in the fluence. A maximum transmittance is observed to be 85% in the visible region for doped films. It is also shown that the bandgap of undoped and doped ZnO films is varied using SHI irradiation. The modifications of structural and optical properties are explained in terms of thermal spikes induced by SHIs.
