Inherently Eu²⁺ /Eu³⁺ Codoped Sc₂ O₃ Nanoparticles as High-Performance Nanothermometers

Area of Science:

• Nanomaterials Science
• Solid-State Chemistry
• Optical Thermometry

Background:

• Contactless and noninvasive temperature probing at the nanoscale is crucial for various scientific applications.
• Luminescent nanothermometers offer a promising solution for precise temperature measurements.
• Existing nanothermometers often face limitations in range, sensitivity, or stability.

Purpose of the Study:

• To synthesize and characterize novel europium (Eu²⁺/Eu³⁺) codoped scandium oxide (Sc₂ O₃) nanoparticles.
• To develop a highly efficient ratiometric nanothermometer for wide-range temperature measurements.
• To investigate the potential for tunable temperature probing by codoping with additional rare-earth elements.

Main Methods:

• One-step thermolysis reaction for synthesizing Eu²⁺/Eu³⁺ codoped Sc₂ O₃ nanoparticles.
• In situ reduction of Eu³⁺ to Eu²⁺ using oleylamine during synthesis.
• Utilizing stable Eu³⁺ emission as an internal standard and temperature-sensitive Eu²⁺ emission as the probe.
• Characterization of luminescence properties for temperature sensing performance.

Main Results:

• Successfully synthesized Eu²⁺/Eu³⁺ codoped Sc₂ O₃ nanoparticles with uniform distribution.
• Demonstrated a ratiometric nanothermometer with a wide temperature probing range (77–267 K).
• Achieved high repeatability (>99.94%) and high relative sensitivity (3.06% K^-1 at 267 K).
• Showcased tunable temperature probing by incorporating terbium (Tb³⁺) as an additional reference.

Conclusions:

• The developed Eu²⁺/Eu³⁺ codoped Sc₂ O₃ nanoparticles represent a robust and efficient ratiometric nanothermometer.
• The in situ reduction strategy ensures optimal performance and simultaneous excitation of both Eu²⁺ and Eu³⁺.
• The codoping approach with Tb³⁺ offers a pathway to tunable temperature sensing ranges for diverse applications.