The luminescence of CaWO4: Bi single crystals

Influence of doping with Bi3+ ions and Bi3+-Na+ or Bi3+-Li+ ions pairs on luminescence, emission kinetics and light yield of CaWO4 crystals has been investigated. It has been shown that under excitation in the A-band at 272 and 287 nm, related to the Bi3+ ions absorption, the luminescence peaked at 468 nm decaying with time τ=0.41 μs is observed. For bismuth concentration 50-500 ppm and the equimolar concentrations of the Bi3+ ions accompanied by Na+ or Li+ ions compensators the significant suppression of the phosphorescence peaked at 520 nm, related to the defect WO3-VO complex, and an improvement of scintillation characteristics of the CaWO4 are noticed. Energy transfer from the defect WO3-VO and regular WO42− oxy-anions to Bi3+ ions have been observed at room temperatures and discussed.