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

Abstract 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+,xYb3+ was determined to be ×  = 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 I522/I554 and I660/I522 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 SA increased first and then decreased by utilizing I522/I554, but showed continuous decrease by using I660/I522. For the relative sensitivity SR, it has been found that the SR 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.