Decay of Phosphorescence in CaCO3, MgCO3, CaMg(CO3)2, and CaSO4

Abstract

The decay of phosphorescence in CaC${\mathrm{O}}_3$, MgC${\mathrm{O}}_3$, CaMg${\left(\mathrm{C}{\mathrm{O}}_3\right)}_2$, and CaS${\mathrm{O}}_4$ obeys the relation $I=I_0{\left[\frac{b}{\mathrm{}(b+t)\mathrm{}}\right]}^m$, where the parameters $b$ and $m$ are functions of the temperature of decay and the fraction of initially filled traps (i.e., the excitation time). This result can be derived from the usual model for second-order decay, and the results predicted for the behavior of $b$ and $m$ with temperature and excitation time are the same whether it is assumed that the traps and luminescent centers are independent of each other or are due to the same defect or impurity center. It is shown, however, that in both cases the predicted behavior is not in agreement with the experimental results for the crystals studied here.