Growth and vibrational spectroscopy of K2LiyNixCo1-x(SO4)2• 6H2O (y=0. 1; 0. 2; 0. 3; 0. 4) crystals

The mixed crystals of the Tutton's salt doped with Li following the empirical formula K2LiyNixCo1-x(SO4)(2)center dot 6H(2)O, 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.