Highly sensitive optical nanothermometry using Er3+-doped GdOF nanoparticles: synthesis, characterization, and temperature sensing applications

The synthesis and characterization of 1 mol% Er 3+ -doped GdOF nanoparticles for use as optical nanothermometer are presented. The nanoparticles were synthesized using a microwave-assisted solvothermal method, followed by calcination at 700°C to obtain the oxyfluoride phase. Temperature sensitivity was evaluated using the fluorescence intensity ratio (FIR) method, based on the thermally coupled 2 H 11/2 and 4 S 3/2 levels of Er 3+ over the 294 - 423 K range. The results demonstrate a high sensitivity, with an absolute sensitivity of 3.07×10 -3 K -1 at 423 K and a relative sensitivity of 1.25% K -1 at 294 K. These competitive values position Er 3+ -doped GdOF nanoparticles as promising candidates for temperature sensing applications in biomedicine and nanotechnology, offering advantages over other Er 3+ -based nanothermometers in different host matrices. • Highly sensitive Er 3+ -doped GdOF nanoparticles for optical nanothermometry. • Microwave-assisted solvothermal synthesis ensures high crystallinity and phase purity. • Fluorescence Intensity Ratio (FIR) method provides accurate temperature sensing (294–423 K). • Superior thermal sensitivity compared to other Er 3+ -based nanothermometers. • Potential applications in biomedical and nanotechnological temperature monitoring.