Positive luminescence thermal coefficient of Mn2+ ions for highly sensitive luminescence thermometry

Luminescence thermal quenching phenomenon is a major limitation in the development of luminescent thermometers of high-resolution operating in the temperature range above 400 K. Therefore, in order to circumvent this limitation, in this work CaGa4O7:0.01 % Mn2+, 0.05 % Cr3+ is proposed as a new biocompatible thermometer in which the luminescence intensity of the Mn2+ -based emission is thermally enhanced providing a high signal-to-noise ratio at temperatures even above 520 K. Therefore, as shown, the intensity ratio of Mn2+ and Cr3+ ions can be successfully used for ratiometric temperature readout not only for thermal sensing with a relative sensitivity of 2.08 % K−1 at 403 K and δT = 0.1 K and for 2-dimensional thermal imaging using a digital camera.