SUPPRESSION OF SELF-TRAPPED EXCITON LUMINESCENCE IN LA3+-DOPED AND ND3+-DOPED BAF2

The self-trapped exciton (STE) luminescence at 300 mm with a decay time of 620 ns in pure BaF2 can be suppressed by La3+ or Nd3+ doping. Crystals were studied with La concentrations ranging from 0.2 mol% to 22 mol% and Nd3+ 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 La3+ 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 La3+-doped crystals can also be employed for explaining similar aspects of the STE luminescence observed for the Nd3+-doped BaF2 crystals.