Thermal assistance in the optically stimulated luminescence of superluminous Sr4Al14O25: Eu2+,Dy3+

The thermally induced increase in optically stimulated luminescence of super-luminous Sr4Al14O25:Eu,Dy is reported. To isolate this thermal assistance to emission, which is otherwise obscured by high intensity transient emissions, stimulation was done using 870 nm infrared light. The optically stimulated luminescence intensity measured between 20 and 200 degrees C goes through a peak. The profile is reproducible and is independent of whether the measurements are made with the temperature increasing or decreasing. The initial increase in signal is ascribed to thermal assistance and the subsequent decrease is due to thermal quenching. The activation energy of thermal assistance was determined as 0.30 +/- 0.01 eV. The corresponding value for the activation energy for thermal quenching is also reported as are methods for determining these parameters from the temperature dependence of the luminescence. The thermal assistance effect is explained with reference to a configurational coordinate model.

Automated summary

The thermally induced increase in optically stimulated luminescence of super-luminous Sr4Al14O25:Eu,Dy was studied using 870 nm infrared light stimulation. The luminescence intensity peaked between 20 and 200 degrees C, with a reproducible profile independent of temperature direction. The thermal assistance and quenching effects were explained, with activation energies determined and methods for measuring temperature dependence of luminescence discussed.