Christine Reinhard and Hans U. Güdel
Cooperative processes in Pr³⁺ and V³⁺ codoped Cs₂NaScCl₆
J. Lumin. 102-103, 373-379 (2003)                 

Abstract: 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.