Cooperative processes in Pr3+ and V3+ codoped Cs2NaScCl6

A crystal of Cs2NaScCl6 codoped with Pr3+ and V3+ was synthesized and studied by high-resolution optical spectroscopy. The principal objective is the search for a material containing a broad-band absorber in the near-IR which is able to sensitize a near-IR to visible upconverter. V3+ in a chloride environment does absorb in the near-IR. However, the V3+ to Pr3+ energy-transfer step is extremely inefficient in the title compound. Nevertheless we were able to identify and characterize a new type of upconversion process.