Scintillation and luminescence properties of Ce3+ doped K2LaCl5

Scintillation and luminescence properties of K2LaCl5 : Ce3+ with Ce3+ concentrations between 0.001% and 10% are presented. Under optical excitation the characteristic double-peaked Ce3+ luminescence is observed between 330 and 350 nm. Under X-ray excitation also self-trapped exciton (STE) luminescence ranging from 250 to > 500 nm is also observed. At low Ce3+ concentration the STE luminescence is dominant. The largest light yield is observed for K2LaCl5 : 10% Ce3+ where 97% of the emission intensity stems from Ce3+ luminescence. For this sample the light output is 50,000 ph/MeV under continuous X-ray excitation and 31,300 ph/MeV under gamma excitation. Two models an proposed to explain the energy transfer from the host lattice to the Ce ions. At low Ce3+ concentration energy transfer by STE diffusion is proposed, whereas at high Ce3+ concentration energy transfer by bimolecular recombination is held dominant. (C) 1999 Elsevier Science B.V. All rights reserved.