Crystallization and characterization of K2NixCo1-x(SO4)2·6H2O mixed crystals for ultraviolet light filters and sensors

• Published in: Solid state sciences 2023-09, Vol.143, p.107261, Article 107261
• Main Authors: Abdulwahab, A.M., Gaffar, M.A., El-Fadl, A. Abu
• Format: Article
• Language: English
• Subjects: Dehydration; Infrared spectra; Mixed crystals; Tutton salts; Ultraviolet light filter
• ISSN: 1293-2558; 1873-3085
• DOI: 10.1016/j.solidstatesciences.2023.107261

Mixed Tutton salts K2NixCo1-x(SO4)2·6H2O (KNICOSH) single crystals with x = 0, 0.20, 0.50, 0.80 and 1 were grown at 309 K using the slow evaporation of supersaturated aqueous solutions. X-ray diffraction analysis revealed the monoclinic structure, space group P21/a (C_2 h^5) and Z = 2, for each crystal obtained in this work. Thermal investigation showed several peaks that indicated the dehydration process, the exothermic reactions and melting points of K2NixCo1-x(SO4)2·6H2O crystals. The temperatures of these peaks increased with increasing x value, and it means that the crystals rich with Ni have higher thermal stability than those rich with Co. The infrared spectra of KNICOSH crystals showed three types of modes (internal modes of the sulfate ion, internal modes of water and librational modes of water). The wavenumber of internal modes of water increased systematically with increasing Ni content which indicate that the water molecules in KNISH crystal have hydrogen-bonding stronger than that of KCOSH crystal. The wavenumber of other infrared spectra modes changed unsystematically with increasing Ni content. K2Ni0.50Co0.50(SO4)2.6H2O crystal has the most absorption for the light at the visible range while at the ultraviolet region the absorption is low (high transmittance). This behavior enhanced its efficiency for using in ultraviolet light filters and sensors. [Display omitted] •Single crystals of KNICOSH were grown using slow evaporation.•All obtained crystals have the monoclinic structure.•The Ni rich crystals have thermal stability better than those rich with Co.•Water molecules in KNISH have hydrogen-bonding stronger than KCOSH.•KNI50CO50SH crystal has high efficiency for ultraviolet filters and sensors.