Luminescent Er3+ centers in CaSc2O4:Er3+:Yb3+upconversion phosphor

The structure of luminescent centers in the upconversion material Er:Yb:CaSc2O4 is investigated using high-resolution optical spectroscopy methods at low temperature (10K). Two luminescent centers were identified in Er(2 at%):CaSc2O4: one corresponding to Er(3+ )on Ca2+ positions (center I) and one corresponding to Er3+ on Sc3+ positions (center II). Both X-ray diffraction and optical spectroscopy indicate an increase in the population of center II with the increase of doping concentrations. The Stark energy levels corresponding to multiplets I-4(15/2), I-4(13/2), F-4(9/2) and S-4(3/2) were obtained for the two luminescent centers, using selectively-excited luminescence. Upconversion measurements performed at low temperatures (10K) showed that the contribution of center I is dominant. The temperature dependence of the upconversion intensity and of the red to green ratio is discussed.

Automated summary

The study investigated luminescent centers in Er:Yb:CaSc2O4 and observed two distinct centers, with one dominating at low temperatures, while the population of the other center increased with doping concentrations. This study also explored the Stark energy levels for both centers and discussed the temperature dependence of upconversion intensity.