Optical temperature sensing of hexagonal Na0.82Ca0.08Er0.16Y0.853F4 phosphor

The hexagonal Na0.82Ca0.08Er0.16Y0.853F4 phosphor was prepared by the high temperature solid-state reaction. Novel six-photon ultraviolet up-conversion emissions in the range of 260-320 nm are observed under 1.54 mu m excitation. Using the ratio of 523 nm and 542 nm fluorescence emissions, low-temperature optical temperature sensing in the resulting phosphor is studied. The temperature sensitivity of the resulting phosphor in the region of 5-300 K is obtained by measuring the temperature dependent fluorescence intensity ratio of the 523 nm and 542 nm emissions originated from two thermally coupled H-2(11/2) and S-4(3/2) emitting levels. The temperature sensitivity with a maximum sensitivity of 0.0022 K-1 at 338 K is obtained experimentally. The results reveal that the resulting phosphor may be a promising material for the sensing system at low temperature.