Structure, Morphology and Upconversion Luminescence of Rare Earth Ions Doped LiY9(SiO4)6O2 for Temperature Sensing

To develop novel upconversion (UC) luminescence materials for optical temperature sensing applications, the rare earth (Yb3+, Er3+, Ho3+, and Tm3+) ions doped LiY9(SiO4)(6)O-2 phosphors were developed. The single-phase samples were confirmed by XRD patterns. The morphology characteristics were studied via SEM and TEM techniques. When excited by 980 nm, the optimal doping concentrations for Er3+/Ho3+/Tm3+ were determined in the UC emission spectra and their characteristic emission peaks were attributed. The temperature -dependence of the UC spectra was investigated by using different strategies. The maximum absolute sensitivities were calculated to be 4.77 X 10(-3) K-1 for 1522/1548 (Er3+), 0.034 K-1 for 1661/1522 (Er3+), 0.034 K-1 for 1660/1548 (Ho3+), and 2.74 X 10(-4) K-1 for 1695/1789 (Tm3+), which show high sensitivity values. Among these activator ions, the Tm activated sample demonstrates the largest relative sensitivity. Compared with some previous lanthanide ions activated temperature-sensing luminescence materials, the present phosphors exhibit improved sensitivities and could show potential applications for temperature sensors.