Suppression of self-trapped exciton luminescence in La3+- and Nd3+-doped BaF2

The self-trapped exciton (STE) luminescence at 300 nm with a decay time of 620 ns in pure BaF 2 can be suppressed by La 3+ or Nd 3+ doping. Crystals were studied with La concentrations ranging from 0.2 mol.% to 22 mol.% and Nd 3+ concentrations between 0.15 and 11 mol.% X-ray induced emission spectra at temperatures from 90 K to 430 K and decay-time spectra are presented. Information about trapping of electrons by La 3+ ions and the activation energy for thermal quenching of STE luminescence is obtained from a fit of the experimental data to a model calculation. The conclusions obtained for La 3+ -doped crystals can also be employed for explaining similar aspects of the STE luminescence observed for the Nd 3+ -doped BaF 2 crystals.