Growth of mixed K2(Ni,Co)(SO4)2·6H2O crystals under stationary conditions of supercooling and forced convection of the aqueous solution

Abstract The technique and the scheme of the system for growing single crystals, including complex mixed composition, under stationary conditions of supercooling and forced convection of aqueous solution were described. Solubility in water of various compositions of K 2 Co x Ni 1−x (SO 4 ) 2 ·6H 2 O (KCNSH) and the dependence of Co content in the KCNSH crystal of Co concentration in the saline part of aqueous solutions of KCNSH have been measured in the temperature range of 30–70 °C. It was found that the growth sectors {0 0 1} and {1 1 0} differ in Ni and Co contents. The Ni/Co ratio is dependent on the value of solution supersaturation. The optical transmission spectra of crystals grown showed high transmittance in the UV region of the spectrum and the almost complete absorption of light in the visible spectrum. It is concluded that the crystals grown can be used as efficient UV filters.