V3+ sensitized upconversion in Cs2NaScCl6:Pr3+;V3+ and K2NaScF6:Er3+;V3+

Abstract Photon upconversion (UC) processes from the near-infrared (NIR) to the visible (VIS) are studied in Cs 2 NaScCl 6 :Pr 3+ ;V 3+ and K 2 NaScF 6 :Er 3+ ;V 3+ by high-resolution optical spectroscopy. The transition metal ion with a broad d–d absorption in the NIR acts as a sensitizer and the lanthanide ion as an upconverter. UC processes do occur in both title systems, but with rather low efficiencies. Specific UC mechanisms can be identified from the spectroscopic results.