Abstract: Manganese doped alpha-lithium iodate have been synthesized and single crystals have been grown for nonlinear optical applications. The grown crystal has been subjected to single crystal X-ray diffraction to confirm the structure. The crystalline perfection was assessed by high-resolution X- ray diffractometer (HRXRD). Second harmonic generation (SHG) efficiency was found to be 71 times than that of KDP. The UV–Vis-NIR spectroscopic study revealed that the grown crystal has good optical transparency in the visible region clearly indicates that Mn doped α-LiIO3 crystals can be used as window material in optical instruments. Presence of dopant was confirmed by energy-dispersive spectrometry.
Abstract: Click chemistry is used for synthesizing polymers for second order NLO study. The molecular weights found by gel-permeation chromatography (GPC), were in the range of 7000-55000 g/mol. Differential scanning calorimetry shows glass transition temperature (Tg) above 120 oC. From electronic spectra order parameter of the poled films were calculated to be 0.1-0.5. The change in surface morphology after poling was checked by atomic force microscopy. By using a pulsed Nd:YAG laser (1064nm), the second harmonic generation (SHG) intensity was measured. The SHG intensity was also studied as a function of against temperature and time respectively.
Abstract: L-asparagine L-tartrate (LAT), an organic compound has been synthesized from aqueous solution and bulk single crystal has been grown by slow evaporation technique. Powder X-ray diffraction studies confirmed the monoclinic structure of the grown LAT crystal. The presence of functional groups of the grown crystal was identified by FTIR studies. Linear optical property of the grown crystal was studied by UV-Vis spectral analysis. Microhardness studies reveal that the crystal possesses relatively higher hardness compared to other organic nonlinear optical crystals. Dielectric response of the L-asparagine L-tartrate crystal was analyzed for different frequencies at various temperatures. Kurtz-Perry powder second harmonic generation test confirmed the nonlinear optical properties of the as-grown LAT crystal.
Abstract: Lead zirconium titanate thinfilms have been prepared by the cost effective spin coating method on glass and stainless steel substrate with the following optimized coating parameters, (1) Coating period of the sol - 4th to 5th day, (2) Spin rate – 2500 rpm, (3) Spin time – 10 Sec, (4) Number of coating – 8, (5) Heat treatment temperature - 450 °C and (6) Heat treatment duration – 8 Sec. The developed PZT thinfilms are annealed between the temperature 200 oC and 1000 oC. The XRD profile of all the PZT thinfilms annealed at different temperatures confirm polycrystalline perovskite structure with preferred orientation along (110) plane. The thermal conductivity measurement of the PZT thinfilm samples annealed at different temperatures illustrates a non linear decline with the increase in annealing temperature. The sheet resistance and resistivity measurement of the PZT specimen show a maximum value of 15.6 MΩ/ and 13.7 x 10-6 Ω-cm, for the PZT thinfilm annealed at the temperature 1000 oC. Hardness of the PZT thinfilms annealed at different temperatures is measured in the Vickers scale. A maximum hardness of 740 VHN and a minimum hardness of 220 VHN is observed for the PZT thinfilm annealed at the temperature 1000 °C and 300 °C respectively. The 2D and 3D AFM micrograph of the PZT thinfilm annealed at 1000 °C illustrates fine grain growth, smooth and uniform surface pattern with large number of grain boundaries.
Abstract: Picolinium maleate (PM), a novel organic compound has been synthesised and bulk crystal has been grown from the aqueous solution by slow evaporation technique. The structure of the grown crystal was elucidated by using single crystal XRD analysis and powder XRD pattern further confirmed the crystallinity of the grown PM crystal. The presence of functional groups in PM were identified by FTIR spectral analysis. UV-Vis spectral studies revealed that PM crystals are transparent in the wavelength region 327–1100 nm. The laser damage threshold value of PM crystal was measured using Nd:YAG laser. The second harmonic conversion property was studied by Kurtz and Perry powder technique.
Abstract: We concentrate on the low temperature slow solvent evaporation method and characterization of pure and 1, 10 phenanthraline doped KB5 and describe its potential as a non-linear optical material. The grown crystal has been subjected to single crystal X-ray diffraction analysis to identify the unit cell parameters and crystal system. The presence of carbon, hydrogen and oxygen content were confirmed by CHN analysis. The Kurtz’s-Perry powder SHG efficiency was determined for both pure and 1, 10 phenanthraline doped KB5 crystals as 1.6 and 2.2 times than that of pure KDP. Laser damage threshold studies of the pure and doped KB5 crystals have been found to be Q-Switched Nd-YAG laser.
Abstract: Nickel oxide (NiO) thin films were deposited on glass substrates at various target to substrate distances in the range of 60 to 80 mm by dc reactive magnetron sputtering technique. It was observed that target to substrate distance influenced the morphological, optical and electrical properties of the deposited films. The optical results revealed that the optical transmittance of the films increased with increasing the target to substrate distance upto 70 mm, thereafter it was decreased. The increase in transmittance of the films was due to an increase in size of the grains. The NiO films exhibited an optical transmittance of 60 % and direct band gap of 3.82 eV at target to substrate distance of 70 mm. The films showed high electrical resistivity of 37.3 Ωcm at target to substrate distance of 60 mm and low electrical resistivity of 5.1 Ωcm at target to substrate distance of 70 mm. At high target to substrate distance of 80 mm the electrical resistivity of the film was increased.
Abstract: Tristhiourea Zinc(II)sulphate (ZTS) and rare earth Neodymium(III)Nitrate doped Tristhiourea Zinc(II)sulphate compounds were synthesized and single crystals were grown from aqueous solution by slow evaporation technique. The cell parameters of the grown crystals were evaluated by single crystal X-ray diffraction studies and powder X-ray diffraction analysis further confirmed the crystalline nature of the grown crystals. The presence of functional groups in the grown crystals was confirmed by FTIR analysis. UV-Visible absorption spectra reveal the cutoff wavelengths of grown crystals. TGA/DTA thermal analyses revealed that the materials have good thermal stability. The incorporation of the impurity (Nd3+) entered into ZTS crystals was confirmed by SEM-EDX analysis. The microhardness studies on the grown crystal samples revealed that the hardness increases with applied load for all the grown crystals. From the values of work hardening coefficient, ZTS and Neodymium(III)Nitrate doped ZTS crystals were found to be soft category materials. The second harmonic signal from ZTS and Neodymium(III) Nitrate doped ZTS crystals were tested by Kurtz-Perry method using Nd:YAG laser.
Abstract: Optical quality 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) crystals have been grown by a novel technique. In conventional growth methods, it was difficult to control the position of spontaneous nucleation, number of nuclei, cluster formation and the nucleation period. Difficulty in the nucleation and growth positioning was effectively solved by the slope nucleation method (SNM) and sizable DAST crystal was grown by two zone growth technique (TZGT) using a seed. Furthermore removal and fixing of seed crystal was difficult in the two zone growth technique. In the present study, we could obtain optical quality bulk DAST crystals by combining SNM and TZGT. The growth rates, size are estimated with respect to temperature gradient and slope shape. The structural, functional and optical analyses were carried for the grown crystals and the results are discussed in detail.