A Thermometer Based on Er‐Sensitized Phosphors Gd₂(WO₄)₃:Er,Yb@SiO₂ in Near‐Infrared and Visible Regions

Abstract

Currently, the ratiometric temperature sensing based on thermally coupled levels and nonthermally coupled levels dominates the optical thermometers. Herein, Gd2(WO4)3:Er,Yb@SiO2 phosphors are successfully synthesized by the one‐pot coprecipitation method. The themperature sensing properties based on fluorescence intensity ratio (FIR) at 808 nm excitation are investigated in detail. In the visible region, the maximum relative sensitivity (Sr) of 0.0112 K−1 based on thermally coupled energy levels of Er3+ (2H11/2 and 4S3/2) is achieved at 323 K, whereas the maximum of Sr based on nonthermally coupled energy levels of Er3+ (4I13/2) and Yb3+ (2F5/2) in the near‐infrared region is 0.0035 K−1 at the lowest temperature 303 K, indicating that the thermometer can be used in the biological temperature range. Moreover, to determine which kind of thermal sensing method is more reliable, the relative standard deviation (RSD) is calculated. In comparison, it is confirmed that temperature sensing based on thermally coupled levels is more stable.