Mixed-valent MgAl2O4:Eu2+/Eu3+ phosphor for ratiometric optical thermometry

Novel strategies to obtain remote temperature sensing with good spatial and thermal resolution are in high demand in various applications, where traditional thermometers are inappropriate. The majority of developed luminescence thermometers utilize thermally-coupled levels with their inherent limitation of thermal sensitivity and problems with signal discriminability. We report mixed-valent Eu2+/Eu3+-doped MgAl2O4 phosphor as a ratiometric thermal sensor, which is free of these drawbacks. Different temperature behavior of Eu2+ and Eu3+ emission bands provides luminescence thermometry within range of 298–523 K. High absolute and relative thermal sensitivities of 0.084 K-1 and 0.83% K−1, respectively, as well as sub-degree temperature resolution indicate that MgAl2O4:Eu2+/Eu3+ phosphor is a promising material for optical thermometry.