Photoluminescence properties of Er3+ and Eu3+ ions based on oxide host for optical temperature sensing with high sensitivity.

Abstract Motivated from increasing demands of non-contact optical temperature sensing, the Yb3+-Er3+ and Eu3+ doped NaY9Si6O26 (NYS) oxide phosphors were designed by high-temperature solid-state reaction method. The phase purity of the as-prepared samples was checked from XRD patterns. For the upconversion luminescence in NYS:Yb3+,Er3+, the optimal Er3+ doping content was determined to be 1 mol%, and the characteristic emission peaks of Er3+ were observed in the region of 500-700 nm. In Eu3+ activated NYS phosphors, it has been found that the emissions originating in 5D1 and 5D0 levels demonstrate different change tendencies in intensity with Eu3+ doping concentration. By studying the temperature-dependent luminescent spectra, it was indicated that the emissions intensities from different excited states of Er3+ change differently with temperature. Two kinds of fluorescence intensity ratio (FIR) strategies were used in NYS:10%Yb3+,1%Er3+, containing thermally-coupled levels and non-thermally-coupled levels. In the NYS:3%Eu3+ phosphor, it was found that the FIR for 577 and 536 nm emissions follows a linear relation with temperature. The high sensitivities in the present phosphors indicate the potential application in optical temperature sensing.