Influence of dysprosium concentration on sensitivity of luminescent thermometers of phosphors Ca9Tb(PO4)5(SiO4)F2

Abstract

Tb3+,Dy3+-co-doped Ca9TbxDy1–x(PO4)5(SiO4)F2 phosphors were prepared via high-temperature solid-phase reaction method and the potential application in optical temperature measurements due to their color-tunable property was investigated in detail. The photoluminescence emission (PL) and photoluminescence excitation (PLE) spectra results show that the as-prepared phosphors exhibit both Tb3+ and Dy3+ emissions at 546 nm (5D4–7F5 transition of Tb3+) and 587 nm (4F9/2–6H13/2 transition of Dy3+) upon 376 nm excitation, respectively. In addition, the fluorescence decay analysis shows that the lifetime of the Tb3+ emission rapidly decreases, which confirms the energy transfer existence between Dy3+ and Tb3+. Under 376 nm excitation, the temperature dependence of the fluorescence intensity ratios for the dual-mission bands peaked at 546 and 587 nm was studied in the temperature range from 303 to 573 K. The results show that with the increase of Dy3+ concentration, the relative sensitivity first increases and then decreases, what's more, the maximum relative sensitivity is 3.142 × 10−3%/K for Ca9TbxDy1–x(PO4)5(SiO4)-F2 (x = 0.4). As a consequence, this preliminary study provides a novel method for exploring the novel thermometers.