Luminescence and energy transfer mechanisms in CaWO4 single crystals

► The band structure of CaWO4 was calculated in the framework of DFT LAPW method. ► Calculation results were validated via joint analysis with experimental data. ► The bandgap Eg of CaWO4 was determined as 4.90±0.15 eV. ► The correlation between the band structure and excitation spectrum is demonstrated. ► Influence of competitive relaxation channel on energy transfer to STE is shown.