Down-conversion PL characteristics of CaSrSiO4:Tb3+ nanophosphor and its application on optical low-temperature sensor

The CaSrSiO4 nanophosphor-doped 0.7 mol% Tb3+ ions have been prepared by the high-temperature sintering method. XRD pattern is consistent with the standard card of CaSrSiO4 host, and the average particle size of CaSrSiO4:0.7Tb is about 50 nm. There exist intense green (544, 552 nm) and weak blue (485, 488 nm), yellow (588 nm), and red (625 nm) emissions under the excitation of 325 nm He–Cd laser, corresponding, respectively, to the transitions of Tb3+ ions from 5D4 and its splitting to 7F5,4,6,3,2 energy levels. The low-temperature photoluminescence characteristics of the sample are measured in the range of 290–10 K. The relationship between fluorescence intensity ratio and temperature is FIR = 0.895 + 0.469exp(− 145.8/T) and the maximum value of sensitivity is 17.6 × 10− 4 K− 1 at 70 K, indicating that CaSrSiO4:Tb3+ nanophosphor is a promising sensing material for low-temperature measurement.