A highly sensitive upconverting nano-glass-ceramic-based optical thermometer

Yb/Tm: YF3 nanoparticles embedded transparent bulk glass ceramic was successfully prepared to explore its possible application in optical temperature sensors. Specifically, owing to the competition of electron population in the thermally coupled Tm3+3F2,3 and 3H4 excited states, two upconversion emission bands corresponding to Tm3+: 3F2,3 → 3H6 transition and 1G4→3F4 one exhibited opposite temperature-dependent behaviors, which resulted in monotonous enhancement of the related fluorescence intensity ratio with increase of temperature. As a consequence, Tm3+ activators in the present YF3 glass ceramic had advantages of a high sensitivity of 1.84% per K, an avoidable spectral overlapping and a negligible thermal effect for accurate temperature detecting. [Display omitted] •Yb/Tm: β-YF3 embedded transparent glass ceramic was fabricated.•Glass crystallization induced greatly enhancement of upconversion luminescence.•Different T-sensitive emission behaviors of two thermally coupled states were observed.•Tm3+ fluorescence intensity ratio intensified with increase of temperature.•The glass ceramic exhibited a high sensitivity of 1.84% K−1 and a negligible thermal effect.