Structure, refractive and electronic properties of K2SO4:Cu2+ (3%) crystals

K2SO4:Cu2+ (3%) crystal has been synthesized and its crystal structure is characterized by means of the X-ray diffraction method and discussed within the second coordination environment description. Experimental dispersions of the refractive indices and birefringence have been studied. The introduction of impurity leads to a decrease in refractive indices values for all principal directions and significantly change the absolute birefringence values, without altering the character of the dispersions. Electronic structure and optical spectra of K2SO4:Cu2+ (3%) crystal are calculated using the density functional theory. To verify data of the present band-structure calculations, X-ray photoelectron spectroscopy and X-ray emission spectroscopy were used. These allowed to measure binding energy values of the core-level electrons of the constituting atoms, energy distribution of electronic states within the valence-band region and partial distribution of O 2p states. The experimental data is found to be in good agreement with theoretical band-structure calculations. [Display omitted] •High quality K2SO2 crystals doped by 3% of Cu2+ have been synthesized by slow evaporation technique.•Crystal structure is analyzed within second coordination environment approach.•The influence of Cu2+ doping on refractive properties of the crystal is studied both experimentally and theoretically.•The electronic band structure and origin of the electronic levels are analyzed by means of DFT.•The theoretical band structure data is confirmed by the experimental survey XPS and XES spectra.