Navegando por Autor "Ghosh, Santunu"
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Item Growth and characterization of ammonium nickel-cobalt sulfate Tutton’s salt for UV light applications.(2018) Ghosh, Santunu; Oliveira, Michelle de; Pacheco, Tiago de Sousa; Perpétuo, Genivaldo Julio; Franco, Carlos JoelWe have obtained a set of sample crystals of the family of Tutton’s salt comprise in the isomorphic series with general chemical formula (NH4)2NixCo(1−x) (SO4)2·6H2O, by employing growth from solutions by slow evaporation technique. The samples crystals were characterized by ICP-AES, X-ray powder diffraction analysis, thermogravimetric analysis, UV–Vis-NIR, Raman and FTIR spectroscopy. This type of material has been studied because of its physical and chemical properties not yet understood and they have potential technological applications. Chemical analysis of the samples by ICP-AES method allowed us to investigate the efficiency of the method of growth used. Thermogravimetric analysis provides the information about the thermal stability of the obtained crystals for high temperature applications, and powder X-ray diffraction analysis at ambient and high temperature reveals the structural quality and structural change of the samples respectively. We have used Raman spectroscopy in the range 100–4000 cm−1 and FTIR spectroscopy in the range 400–4000 cm−1 to understand the internal vibrational mode of the octahedral complexes [Ni(H2O)6]2+ and [Co(H2O)6]2+, SO42− and NH4+ tetrahedra. The transmittance of our mixed ammonium nickel cobalt sulfate hexahydrate (ACNSH) crystals is 75% in the UV region, which indicates that they are ideal to use in UV light filters and UV sensors.Item Growth and characterization of potassium cobalt nickel sulfate hexahydrate crystals : a new UV light filter.(2017) Pacheco, Tiago de Sousa; Ghosh, Santunu; Oliveira, Michelle de; Barbosa, Ananias Alves; Perpétuo, Genivaldo Julio; Franco, Carlos JoelSamples of the empirical formula Kþ 2 Ni2þ x Co2þ ð1 xÞ ðSO4Þ 2,6H2O were grown with a partial occupation of the cations Co and Ni. Mixed crystals with good optical quality were obtained by the slow evaporation growth method. In the decomposition process, these crystals suffer a mass loss of approximately 24%, equivalent to water molecules forming octahedral coordination ions of Ni and Co. The optical characteristics of the grown crystals were measured where transmittance reached more than 80% in the wavelength range of 190e390 nm. By Raman spectroscopy, the vibrational modes of SO2 4 , H2O and of the octahedral Ni(H2O)6 and Co(H2O)6 were identified.Item Growth and structural analysis of ammonium nickel cobalt sulfate hexahydrate crystals.(2017) Oliveira, Michelle de; Ghosh, Santunu; Pacheco, Tiago de Sousa; Perpétuo, Genivaldo Julio; Franco, Carlos JoelWe have obtained a set of crystals of the empirical formula (NH4)2NixCo(1−x)(SO4)2 · 6H2O with the different concentrations of Ni and Co, by employing the growth from the solution technique. We have chosen the monocrystal (NH4)2Ni0.3Co0.7(SO4)2 · 6H2O for the structural analysis. The structure was resolved by x-ray diffraction method and refined by the full-matrix least-squares method with the help of SHELXS software. This crystal belongs to a monoclinic space group P21/c with crystal parameters, a = 6.2455 (2) Å, b = 12.5065 (3) Å, c = 9.2303 (2) Å, α = γ = 90°, β = 106.995 (3)°, V = 689.49 (3) Å3, Z = 2. We have shown the configuration of the unit cell of the above monocrystal, along with that we have also reported the length, angles between the bonds and the geometry of the hydrogen bonds of the monocrystal.Item Growth and vibrational spectroscopy of K Li Ni Co SO H O 2 1 42 2 yx x − ( ) . 6 ( 0. 1; 0. 2; 0. 3; 0. 4 y = ) crystals.(2020) Pacheco, Tiago de Sousa; Ludwig, Zélia Maria Da Costa; Dores, Diogo Rubio Sant' Anna das; Perpétuo, Genivaldo Julio; Franco, Carlos Joel; Paiva, Edinei Canuto; Ghosh, SantunuThe mixed crystals of the Tutton’s salt doped with Li following the empirical formula K2LiyNixCo1-x (SO4)2.6H2O, were synthesized from the slow evaporation of the solvent at constant temperature. The presence of K, S, Ni, Co and O elements in the studied crystalline structure was confirmed by EDS spectroscopy using a scanning electron microscope and their quantification including Li was carried out with the help of ICP-OES technique. Raman spectroscopy in the range 100−3600 cm−1, confirmed the presence of tetrahedral (SO4), octahedral complexes Ni(H2O)6, Co(H2O)6, and H2O molecules in the crystal structure. Our UV–vis studies have shown that the mixed crystals have good optical transparency in the ultraviolet (200−350 nm) and infrared (750−1000 nm) region. The direct and indirect optical energy gap of the synthesized crystals were determined from the Tauc’s plot. XRD diffractograms of the sample crystals do not show any specific changes due to the presence of Li ion in the crystalline network.