The temperature sensing properties of Dy3+ and Mn4+ co-doped Ca2LaSbO6 phosphor.

With the rapid development of modern science and technology, non-contact optical thermometry has attracted much attention in various fields. However, conventional temperature sensing methods based on the fluorescence intensity ratio (FIR) usually rely on two thermally coupled energy levels (TCELs), which inherently restrict the further improvement of temperature sensing sensitivity. Herein, a Dy3+ and Mn4+ co-doped Ca2LaSbO6 phosphor was designed and prepared to achieve high-sensitivity temperature sensing. Under 450 nm excitation, both the characteristic emissions of Dy3+ and Mn4+ were clearly observed. As the temperature varies, Dy3+ and Mn4+ exhibit different temperature-dependent luminescence characteristics. Consequently, the fluorescence intensity ratio (FIR) for temperature sensing, based on the luminescence of Mn4+ and Dy3+, achieves excellent performance with a maximum relative sensitivity (SR) of 1.99% K-1 at 425 K and an optimal temperature resolution δT of 0.23 K at 420 K. A reasonable explanation is provided for the strong thermal quenching of Mn4+ emission. The temperature-dependent fluorescence decay curves further demonstrate the existence of an additional non-radiative de-excitation pathway for Mn4+. All these results indicate that the Ca2LaSbO6:Dy3+/Mn4+ phosphor is a promising candidate material for high-sensitivity temperature sensors.