Browsing by Author "R, Arun Kumar"

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    GROWTH AND CHARACTERIZATION OF A NONLINEAR OPTICAL MATERIAL: L-HISTIDINE-DOPED IMIDAZOLINIUM L-TARTRATE
    (SpringerLink, 2019-04-24) P, Dhivya; R, Arun Kumar; T, Theivasanthi; G, Vinitha; M D, Kannan
    Imidazolinium L-tartrate (IMLT) crystals and L-histidine-doped IMLT crystals were grown by slow evaporation technique at room temperature. The powder x-ray diffraction technique confirms the lattice parameters and shifts in the peak positions attributed to the dopant L-histidine. The Fourier transform infrared (FTIR) spectrum reveals the assignments of characteristic bondings present in the grown crystals. The frequency-dependent dielectric constant and dielectric loss of pure and L-histidine-doped IMLT crystals have been investigated by the dielectric measurements. Doping has improved the optical parameters and was studied using UV–Vis-near infrared (NIR) spectral studies. The cut-off wavelengths of pure and 1 mol.% L-histidine-doped IMLT crystals were observed at 234 nm and 229 nm, respectively. The etching study examines the growth mechanism and surface morphology of the pure and L-histidine-doped IMLT crystals. The carbon-hydrogen-nitrogen (CHN) analysis conveys the percentage of carbon, hydrogen and nitrogen elements present in pure and L-histidine-doped IMLT crystals. The consequences of doping L-histidine in IMLT single crystal and their dominance in various properties of the crystal grown in aqueous solution by slow evaporation technique have been explored.
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    INVESTIGATIONS ON THE PROPERTIES OF L-PROLINE DOPED IMIDAZOLINIUM L-TARTRATE (IMLT) SINGLE CRYSTALS
    (SpringerLink, 2021-01-20) P, Dhivya; R, Arun Kumar; G, Vinitha
    In the present work, imidazolinium L-tartrate (IMLT) crystals and L-proline-doped IMLT crystals were grown by slow cooling solution growth technique. The powder X-ray diffraction technique reveals the lattice parameters and strains developed due to the doping of L-proline in 1, 3 and 5 mol concentrations. The transmittance spectrum unveils the contribution of the dopant atoms on the optical property of the grown crystals. Bandgap and cut-off wavelength are affected by the increase in the dopant concentration. The vibrational frequencies around 3132, 2925 and 1438 cm−1 are due to the O–H stretching in the carboxyl group, C–H stretching vibration of carboxyl group and aromatic ring vibrations, respectively, present in the grown crystals are observed in the FTIR spectroscopic analysis. The dielectric constant and dielectric loss of pure and L-proline-doped IMLT crystals with respect to the frequency of the applied electric field have been investigated by the dielectric measurements at room temperature. The surface morphology of the grown crystals was examined by the etching study which reveals the growth mechanism of pure and L-proline-doped IMLT crystals. Etch pits in rectangular pattern were found to appear. The percentages of carbon, hydrogen and nitrogen elements present in pure and L-proline-doped IMLT crystals were determined using CHN analysis. The third-order nonlinear susceptibility was calculated from the nonlinear absorption coefficient and nonlinear refractive index data obtained from the Z-scan analysis. The dopant, L-proline, has altered the properties of IMLT single crystal.
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    STUDY OF EFFICIENT SUSTAINABLE PHOSPHOR IN GLASS (P – I – G) MATERIAL FOR WHITE LED APPLICATIONS FABRICATED BY TAPE CASTING AND SCREEN-PRINTING TECHNIQUES
    (2023-12) Mitrabhanu, Behera; Rajashree, Panda; P, Dhivya; Dhananjay, Joshi; R, Arun Kumar
    n the recent years, phosphor coverted (pc) white light emitting diode (w-LED) has become a crucial and reliable lighting source. The most extensively used phosphor material employed in pc-wLED is the versatile yellow light emitting cerium-doped yttrium aluminium garnet, Ce3+:Y3Al5O12 (Ce:YAG) material. Here, the combination of blue light emitted by InGaN-GaN-based LED chip along with the down-converted yellow light (540 nm) emitted by Ce:YAG phosphor gives rise to the generation of efficient white light. Phosphor-in-glass (P-i-G) composites which are found to be efficient alternatives to phosphor-in-silicones structures are presented in this manuscript. The fabrication of P-i-G material through tape-casting and screen-printing methods are discussed and are critically reviewed. The mechanical and optical properties of the P-i-G samples prepared using the two methods (tape – casting and screen printing) are discussed.