Sensitivity of several optical temperature sensors based on up-conversion emission from ²H_11/2 and ⁴S_3/2 levels of Er³⁺ ion.

Sensing materials	Temperature range (K)	S max (10−3/K)	Temperature (K)	Ref.
KEr3F10:Er3+GC	303–573	3.98	303–573	This work
Sr2YbF7:Er3+GC	300–500	6.21	560	21
CaF2:Er3+glass	303–573	2.38	483	23
CaF2:Er3+GC	303–573	1.63	453	23
Na5Gd9F32:Er3+GC	300–510	1.79	499	22
K3YF6:Er3+GC	300–510	1.27	300	18
NaYF4:Er3+/Yb3+GC	298–693	0.35	560	24