Luminescence intensity ratio based wide range contactless temperature sensing properties of Er3+/Yb3+ ions co-doped La2Ti2O7 ceramics

Abstract

Temperature sensing in the range (93–773 K) using luminescence intensity ratio method has been studied in rare earth ion modified La2-x-yErxYbyTi2O7 powders and ceramics. The optimised composition with (x = 0.025, y = 0.05) shows improved upconversion luminescence. For temperature sensing applications the need for excellent phase purity and better densification is emphasized in ceramics. In comparison to phase-impure calcined powders, single phase dense ceramic shows improved upconversion emission and better thermometric performance. The sintered ceramic is found useful for non-contact temperature sensing with a wider operating temperature range (243–1293 K) in comparison to calcined powders (163–863 K). The optimised phosphor in ceramic form exhibits good linearity in the range (173–393 K). Repeatability experiments reveal measurement accuracy within the range − 0.5 to + 0.8 K. Repeated heating and cooling cycles from 190 to 455 K show minimal thermal fatigue. The precision of the temperature read-out from the optical sensor by the intensity ratio method is found to be better (0.24%) at higher temperatures (>373 K) in comparison to the estimated precision of 2.1% at lower temperatures.