A novel K3(Y0.88Yb0.10Er0.02)Si2O7 silicate phosphor for multi-mode thermometry of high sensitivity through up-conversion luminescence

Non-contract optical thermometry shows great advantages for temperature measurement in harsh environments, and it is highly desired to develop novel and high-performance systems. In this work, a novel K3(Y0.88Yb0.10Er0.02)Si2O7 phosphor was synthesized via solid-state reaction, and its up-conversion luminescence and optical thermometric performance were systematically investigated. Under 980 nm excitation, the K3(Y0.88Yb0.10Er0.02)Si2O7 phosphor showed a strong green UC emission through a three photon process. The phosphor was found well capable of sensing temperature via the multi-modes of fluorescence intensity ratio (FIR) of thermally/non-thermally coupled energy levels and fluorescence lifetime (FL). The maximum absolute (SA) and relative (SR) sensitivities are SA = 156 x 10-4 K-1 (I531/I555, 298 K) and SR = 1.80% K-1 (I519/I555, 298 K) via the FIR mode, and are SA = 661 x 10-4 K-1 (548 K) and SR = 9.77% K-1 (298 K) via the FL mode, which are higher than those of most previous studies.