K₂Co(SO₄)₂ · 6H₂O single crystals of optical quality have been grown and the effect of solution pH on their solubility and transmission spectra has been investigated. A kinetic growth curve is obtained for the (110) face and the onset temperature of dehydration is established for single-crystal samples. The structural quality of single crystals grown at different supersaturations is analyzed.

Large single crystals of copper sulfate pentahydrate CuSO4 · 5H2O of optical quality have been grown; they can be applied as broadband UV optical filters. Their transmission spectra are measured. The

The KH₂PO₄ solubility curves in pure water and in water with the addition of 50 ppm Fe³⁺ were refined. The KH₂PO₄ and KH₂PO₄: Fe³⁺ solutions stability to supercooling was evaluated by polythermal studies of the width of metastable zone. It was shown that Fe³⁺ addition makes the solution more stable. A series of Fe³⁺ doped KDP crystals were grown at different temperature and hydrodynamic regimes at supersaturation level up to 0.45. Their real structure was studied by X-ray projection topography and, as a result, the most suitable growth conditions are chosen. The transmittance spectra of prism sectors with ferric iron concentrations C_Fe up to 102 ppm were obtained. It was found that KDP crystals with C_Fe >60 ppm can be used as optical filters for suppressing transmission in UV-C and UV-B ranges.