Potassium-cobalt sulphate crystal growth assisted by low frequency vibrations

•K2Co(SO4)2·6H2O single crystals were grown from vibrational activated solution.•Growth rate from the activated solution was twice more comparing to common growth.•Vibrational grown crystal has 1 order less dislocation density.•Vibrational grown crystal differed by better transmission and higher microhardness. Single crystals of K2Co(SO4)2·6H2O were grown from solution using the temperature reduction method enhanced by the axial low frequency vibration control technique (AVC-technique). Physical modeling of heat-mass transfer in solution under the AVC action was performed. The growth rate of the AVC grown crystal was found to be twice that of the crystal grown under natural convection conditions. Analysis of spectral characteristics (absorption and Raman spectra) as well as structural properties (dislocation density and microhardness) of the grown crystals showed the significant superiority of the AVC technique for the growth of K2Co(SO4)2·6H2O crystals.