Synthesis, enhanced photoluminescence, and multifunctional applications of CaSr2(VO4)2:Sm3+ phosphor via co-doping with alkali metal (Li+, Na+, K+) ions

In this work, CaSr 2 (VO 4 ) 2 phosphors singly doped with Sm 3+ ions and co-doped with alkali metal (Li + , Na + , and K + ) are prepared by using the high temperature solid state reaction. The X-ray diffraction (XRD) patterns exhibit that all the samples belong to the rhombohedral CaSr 2 (VO 4 ) 2 phase with a space group of R3c (161). Upon excitation with the near-ultraviolet (UV) light, the characteristic Sm 3+ emission lines, with the peak dominated at 605 nm, are achieved. Importantly, the photoluminescence (PL) intensity of Sm 3+ ions can be enhanced significantly by co-doping with Li + , Na + , and K + ions, and the reason can be attributed to the charge-compensated role of the alkali metal ions. Furthermore, the temperature-dependent PL experiments measured in the range of 298–573 K show that the optimal phosphor feature excellent stability against heat, making it suitable for acting as a UV-excited orange-red component for phosphor-converted wLEDs (pc-wLEDs). Besides, the PL intensity change of Sm 3+ between 4 F 3/2 → 6 H 5/2 (531 nm) and 4 G 5/2 → 6 H 5/2 (562 nm), 4 F 3/2 → 6 H 5/2 (531 nm) and 4 G 5/2 → 6 H 7/2 (605 nm), and 4 F 3/2 → 6 H 5/2 (531 nm) and 4 G 5/2 → 6 H 9/2 (645 nm) is also analyzed further in the temperature range from 298 K to 973 K, and the results show that the obtained phosphors are suitable for applying in thermometry. Obviously, we reveal multifunctional applications of the obtained phosphors for UV-excited pc-wLEDs and thermometry.