Low temperature fluorescence thermometer application of long afterglow phosphorescent SrAl12O19:Eu2+,Dy3+ crystals

Abstract

Photoluminescence from long afterglow phosphorescent SrAl12O19:Eu2+,Dy3+ phosphor crystals have been studied for a fluorescence thermometer at a temperature lower than 200K. Broadband emissions peaking at λ=404 and 519nm are observed from the crystals at room temperature. The λ=519nm emission is strongly coupled with hole traps generated by the auxiliary activator, which dominates long afterglow phosphorescence from the crystals. The lifetime of the λ=519nm emission was, therefore, much longer than that at λ=404nm. The intensity of the λ=404nm emission decreases with decreasing temperature and it also decreases with increasing in the intensity of λ=371nm emissions due to P7∕26-S7∕28 transition. The intensity of λ=371nm emissions is found to be extremely sensitive to the temperature below 200K. The peak intensity ratio between λ=371nm emissions and the λ=404nm emission is effective for the highly sensitive measurement of a temperature lower than 200K.