Comments on 'Removal of sodium from TLD CaSO4:Dy'

In a recent paper, it was reported that a combination of water washing and recrystallization removes sodium from the thermoluminescent dosimetry grade CaSO4:Dy phosphor and improves its dosimetric characteristics such as fading and glow curves. This work is criticized by another author pointing out that this treatment is unnecessary and very complicated to use in routine large scale preparations of CaSO4:Dy. The best procedure recommended is to start with the reagent grade CaSO4:2H2O which has least sodium content. The glow curve and fading characteristics of CaSO4:Dy manufactured from these samples are satisfactory. (U.K.)