ABSTRACT
Predicting the thermometric performance of diverse materials will facilitate the selection and design of nanothermometers to suit complex environments and specific signal outputs while saving much time and expense. Herein we explore and unveil the thermal-coupled thermometric performance of Er3+/Yb3+ codoped in a set of host lattices via the chemical bond theory of complex crystals. The unknown B and ΔE values of the thermometry are accurately estimated by the chemical bond parameters, further deepening our cognition of the correlation between the luminescence properties of Er3+ ions and the microscopic crystal structure. This allows us to precisely forecast the thermal-coupled thermometric performance of Er3+ for varying host lattices in advance.
ABSTRACT
The fabrication of a multifunctional sensor together with a widening temperature-sensing range is an essential challenge in optical thermometers especially for trivalent lanthanide-doped materials. Herein, we design a wide range, highly sensitive, and multifunctional thermometer by exploiting the emission spectrum of Eu3+ ions, and further detailed discussion has been made on the new temperature-sensing mechanism. The sensor can be operated between 358 and 548 K with a maximum relative sensitivity ( Sr) of 0.93% K-1 at 358 K, which is higher than that of most temperature-sensing materials. A paramount superiority is that the calibration parameter can be directly calculated from the single Eu3+ emission spectrum, avoiding the demand of other calibrations, which realizes the coexistence of a simple structure and high precision. Furthermore, other up-conversion thermometers based on Er3+/Ho3+/Yb3+ co-doped Ba2TiGe2O8 (BTG) phosphors as well as the down-conversion thermometer based on Eu3+-doped Ba2TiGe2O8 (BTG:Eu3+) phosphor have been synthesized for comparison, and the results show that the novel thermometer (BTG:Eu3+) has a much higher sensitivity than that of the traditional thermometers (BTG:Er3+/Ho3+/Yb3+). In addition, the versatility of the phosphor (BTG:Eu3+) is simultaneously reflected in its applications to red phosphor for white-light emitting diodes (W-LEDs) and plant growth lamps. All of the results suggest that BTG:Eu3+ could be a good candidate with its highly sensitive Sr value for optical thermometry and as a safety sign in high-temperature environments.
