Precision evaluation of phosphors for the lifetime method in phosphor thermometry

The precision of the lifetime method in phosphor thermometry was examined in terms of the uncertainty in temperature prediction. Such uncertainty can be estimated using the rate of change in lifetime with temperature (lifetime sensitivity) and the uncertainty in measured lifetime. This uncertainty depends on phosphorescence characteristics such as phosphorescence intensity and lifetime decay shape. In this study, we proposed a method of calculating uncertainties in measured lifetimes by the estimated regression coefficients in measured decay signals of phosphors. To demonstrate this evaluation, the uncertainties in the predicted temperatures of some common phosphors (MFG, GGG:Cr, Y₂O₃:Eu) were calculated. Consequently, the temperature predictions by the lifetime method with MFG, GGG:Cr, and Y₂O₃:Eu showed high precision at about 800 K, 700 K, and 900 K, respectively. This method of evaluating precision by using both lifetime sensitivity and uncertainty in lifetime helps to improve the appropriate use of phosphors for the lifetime method in phosphor thermometry.