Papers by Keyword: Growth from Solution

Abstract: Nanocrystalline Cobalt-doped TiO₂ was prepared by Sol-Gel technique, followed by freeze-drying treatment at-30°C temperature for 12hrs. The obtained Gel was thermally treated at 200,400,600, 800°C. 1%, 2% and 4% Cobalt doped TiO₂ nanopowder has been prepared X-ray Powder Diffraction (XRD), Scanning Electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), was used to study its structural properties. The XRD pattern shows the coexistence of anatase phase and rutile phase. Thermal gravimetric analysis shows Cobalt concentration affects thermal decomposition. UV-Vis Spectroscopy, Photo luminescence (PL), was used to study its Optical properties. Optical Bandgap were calculated with the incorporation of different concentration of cobalt. UV-Visible spectroscopy show variation in band gap for the sample treated at different temperature for same concentration. All Cobalt doped TiO₂ nanostructures shows an appearance of Red shift relative to the bulk TiO₂. The determination of magnetic properties was also carried out by Vibrating Sample Magnetometer.

Abstract: Barium strontium titanate nano powders were prepared by mixing ethanol solution of tetrabutyl titanate with an aqueous solution of Ba(OH)₂•8H₂O and Sr(OH)₂•8H₂O with a certain molar ratio of barium to strontium at 40°C－95°C. The products were characterized by thermogravimetry (TG), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM) and atomic force microscopy (AFM). The results show that the powders prepared with the reactant concentration of 0.8M are spherical in particle shape with the grain size of 50nm－65nm. When the annealing temperature of the powders is higher than 906°C, the hydroxyl groups existed in barium strontium titanate lattice are removed. XRD analysis demonstrate that the as-prepared powders are cubic phase. All the diffraction peaks are shifted towards higher diffraction angles and the lattice parameter a calculated decreases linearly with serial decrease of the molar ratio of barium to strontium.

Abstract: Influence of Glycine dopant in KHP single crystals have been investigated by slow evaporation solution growth technique. Concentration of Glycine in the KHP crystal was optimized and subjected to various spectral studies. Powder X-ray diffraction study reveals the orthorhombic structure of the grown pure and doped KHP crystals. The chemical components present in the crystals were confirmed with the help of FTIR spectrum. The enhancement of optical transparency in the doped KHP crystal was verified by UV-visible spectrum. The refractive indices along b-axis of the grown crystals were measured with Metricon-prism coupler instrument. The emission of green light confirms the SHG properties of the grown crystals.

Abstract: A nonlinear optical material Niobium doped L-Prolinium Picrate was synthesized and grown as single crystals by slow evaporation method. The grown crystals were subjected to structural, elemental, thermal, optical and dielectric studies. The structural analysis reveals that Nb : LPP belongs to the monoclinic crystallographic system with space group P21. Optical transparency of the grown crystals was investigated by UV-vis-NIR spectrum. The thermal analyses reveal that Nb doped L-Prolinium Picrate is thermally stable up to 185 °C. The dielectric constant and dielectric loss of the crystal were studied as a function of frequency. The nonlinear optical property of the grown crystal was confirmed by the Kurtz-powder second harmonic generation test and the results are compared with pure LPP. Mechanical strength of the crystal was also carried out by Vicker’s micro hardness test.

Abstract: Rare earth doped potassium hydrogen phthalate (KHP) single crystals have been grown by slow evaporation technique. Single and powder X-ray diffraction analysis confirms the structural and crystallinity of grown crystals. The functional groups of pure and doped KAP crystals have been identified by FTIR spectral studies. UV-Vis studies explore the optical transmittance of the grown crystals in the entire visible region. Nonlinear optical property of the pure and doped KHP crystals was confirmed by Kurtz-Perry powder test.

Abstract: Abstract. An organic NLO material L-Valinium Picrate (LVP) doped with nickel sulphate (5 mol %) was synthesized and crystals were grown from aqueous solution using slow evaporation method. The solubility, metastable zone width and induction period were determined. The second harmonic generation (SHG) relative efficiency of the LVP (Ni2+) 5 mol% is found to be 260 times higher than that of a standard reference material potassium dihydrogen phosphate (KDP) and 43 times of that of urea.

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: 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: 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: Monodispersed nanotriangles of gold have been prepared by a simple reaction between HAuCl₄·4H₂O, KOH and NH₂OH·HCl in the presence of gelatin. Gelatin played a decisive role as an inhibitor of the direct reaction of NH₂OH with AuCl₄- and coagulation of the growing gold in producing the triangle. In the absence of gelatin, we can only obtain irregular large gold particles. The products were characterized by X-ray powder diffraction, transmission electron microscopy and UV-visible absorption spectroscopy.