The thermo-optic relevance of Ho in fluoride microcrystals embedded in electrospun fibers.

Na(Y Ho Yb )F/PAN (NYF-HY/PAN) composite fibers were synthesized using an electrospinning method, and the sub-micron crystals embedded in the fibers had complete hexagonal crystal structures. Under 977 nm laser excitation, strong green and red up-conversion (UC) emission that originated from flexible fibers were due to the radiative transitions (F, S) → I and F → I of Ho, respectively. The effective green fluorescence emission (539 and 548 nm) can be applied to micro-domain non-contact temperature measurements, realizing rapid and dynamic temperature acquisition in a complex environment without destroying the temperature field. In the temperature range of 313-393 K, the absolute and relative sensitivity of the fibers are 0.00373 K and 0.723% K, respectively, which indicates that the NYF-HY/PAN composite fibers have good thermal sensitivity. Composite fibers in which crystallites are embedded have superior properties, with great stability, high sensitivity, and excellent flexibility, providing a reliable reference for developing temperature-sensing materials for the biomedical field.