Optical temperature-sensing properties based on upconversion luminescence of La9.31Si6.24O26:Er3+,Yb3+ with different strategies

A series of novel La9.31Si6.24O26:Er3+,Yb3+ (LS:Er3+,Yb3+) luminescent materials have been successfully synthesized by conventional solid-state reaction method. The phases, morphologies and upconversion (UC) luminescence properties were systematically researched by XRD, SEM, PL spectra, etc. The optimum Yb3+ concentration in LS:1%Er3+,xYb(3+) was determined to be x = 15%, above which the concentration quenching effect appeared due to the increasing energy back transfer from Er3+ to Yb3+. Meanwhile, the FIR technique (by using I-522/I-554 and I-660/I-522 of Er3+) was employed to study the temperature-sensing performance. As the rise of temperature for all the different Yb3+ concentrations, the values of the absolute sensitivity S-A increased first and then decreased by utilizing I-522/I-554, but showed continuous decrease by using I-660/I-522. For the relative sensitivity S-R, it has been found that the S-R values for all the samples exhibited gradual decrease with rising temperature. Besides, the experiment of the heating-cooling cycles between 283 and 523 K proved that the LS:Er3+,Yb3+ material has good reversibility and repeatability. The above results indicated that the LS:Er3+,Yb3+ may be a potential candidate for optical temperature sensor. (C) 2021 Elsevier B.V. All rights reserved.