Multiple Temperature-Sensing Behavior of Green and Red Upconversion Emissions from Stark Sublevels of Er3+

Abstract

Upconversion luminescence properties from the emissions of Stark sublevels of Er3+ were investigated in Er3+-Yb3+-Mo6+-codoped TiO2 phosphors in this study. According to the energy levels split from Er3+, green and red emissions from the transitions of four coupled energy levels, 2H11/2(I)/2H11/2(II), 4S3/2(I)/4S3/2(II), 4F9/2(I)/4F9/2(II), and 2H11/2(I) + 2H11/2(II)/4S3/2(I) + 4S3/2(II), were observed under 976 nm laser diode excitation. By utilizing the fluorescence intensity ratio (FIR) technique, temperature-dependent upconversion emissions from these four coupled energy levels were analyzed at length. The optical temperature-sensing behaviors of sensing sensitivity, measurement error, and operating temperature for the four coupled energy levels are discussed, all of which are closely related to the energy gap of the coupled energy levels, FIR value, and luminescence intensity. Experimental results suggest that Er3+-Yb3+-Mo6+-codoped TiO2 phosphor with four pairs of energy levels coupled by Stark sublevels provides a new and effective route to realize multiple optical temperature-sensing through a wide range of temperatures in an independent system.

A Theoretical Framework for Ratiometric Single Ion Luminescent Thermometers—Thermodynamic and Kinetic Guidelines for Optimized Performance

“…From Equation (22), it can then be easily concluded that for a given energy gap, the most responsively detected temperature is in agreement with reported earlier findings. [ 112,204,242 ]…”

“…in agreement with reported earlier findings. [112,204,242] So far, Equation ( 24) is still very specific for a certain choice of a luminescent ion, because it depends on the ion-related energy gap ΔE 21 . In order to become independent from any specific luminescent system and allow for general predictive guidelines, both the thermal response S a (T) and the relative sensitivity S r (T) can be normalized with respect to their values at T opt .…”

Investigation on the Fluorescence Intensity Ratio Sensing Thermometry Based on Nonthermally Coupled Levels

“…Besides temperature sensitivity, temperature accuracy δT is another parameter to characterize the optical thermometer, being estimated as 31,32…”

Controlling red upconversion luminescence in Gd2O3:Yb3+–Er3+nanoparticles by changing the different atmosphere

“…5(a)-(c), the red emission decreased when increasing the temperature from 20 to 100 C, which was in accordance with the classical theory of thermal quenching. 50 Quantitative temperature dependent intensity analysis in Fig. 5(c) shows that the Gd 2 O 3 -O 2 sample had better thermal stability than the Gd 2 O 3 -O 2 -free sample.…”