Molten salt synthesis Er3+/Yb3+/Sr2+ doped L-Ta2O5 with intercalated intergrowth structure boosting pure green upconversion luminescence

Abstract

Er3+/Yb3+/Sr2+ doped L-Ta2O5 upconversion phosphor was synthesized by employing molten salt method with B2O3 as solvent. The results of high-resolution transmission electron microscopy (HRTEM) showed that Er3+/Yb3+/Sr2+ was intercalated intergrowth in L-Ta2O5. This structure facilitates energy transfer from Yb3+ to Er3+, which induces outstanding pure green upconversion luminescence (UCL) intensity. The green UCL integrated intensity of L-Ta2O5:Er3+/Yb3+/Sr2+ was 1.53 and 3.14 times that of β-NaYF4:Er3+/Yb3+ and the optimal NaY(WO4)2:Er3+/Yb3+ samples, respectively. This absolute and relative temperature sensitivity reached 1.383% and 0.992% K-1, respectively. The shift rate for peak centroids can reach 0.273 nm/GPa under high pressure. L-Ta2O5:Er3+/Yb3+/Sr2+ with the excellent performance can be used in the fields of UCL display, temperature and pressure sensing.