Conversion of ultraviolet and infrared to visible light in Er3+ and Dy3+ co-doped CsGd2F7

The CsGd₂F₇ crystal co-doped with 1 at% Er³⁺ and 0.2 at% Dy³⁺ ions was studied using the excitation of both synchrotron radiation and 355 nm laser. All the emission bands were assigned by using the Dieke diagram together with the conclusions from relaxation kinetics studies. The onset of the 4f–5d transition bands and the centers of charge transfer bands were also calculated for the lanthanide series CsLn₂F₇ and the results were used to assign the bands and peaks in the excitation spectra. The energy transfer and relaxation processes in CsGd₂F₇ were thoroughly analyzed. Quantum cutting downconversion of one vacuum ultraviolet to two visible photons was realized under 154 nm excitation. Upconverted green emission was observed under 980 nm excitation.