Mn4+/Eu3+ co-doped fluoride toward a blue light-excited optical fiber thermometer.

Abstract

The ongoing development of ratiometric optical thermometry is mainly trapped in thermally coupled levels of rare-earth ions and inefficient ultraviolet excitation. Herein, a new-type multiple sharp line emitting, blue light-excited K2NaInF6:Mn4+, Eu3+ fluoride phosphor has been reported as a ratiometric thermometer. The f-f transition of Eu3+ paves a steady reference to a highly temperature sensitive Mn4+d-d transition and enables high relative sensitivity of 1.65% K-1 at 573 K. An optical fiber thermometry on a household oven with a relative standard deviation of 0.11% surpasses the standard of precision measurement, showing great potential in practical application. This discovery offers a highly sensitive neotype blue light-excitable ratiometric temperature sensor, that is Mn4+-doped fluoride, promoting practical applications of optical thermometry.