Conversion of VUV to UV and visible in K5Li2LnF10 containing rare-earth from cerium group (Ln=La3+, Ce3+, Pr3+, Nd3+)

The potential of single crystals K5Li2LnF10, for applications as VUV excited phosphors has been examined. The crystals were doped with lanthanide ions (Ce3+-Nd3+) with concentrations up to 100 at%. The self-quenching of luminescence is strongly reduced in this material. Luminescence spectra in the 50,000-10,000 cm-1 range and excitation spectra in the 40,000-250,000 cm-1 spectral range have been recorded at room and low temperature. Intense visible emission has been observed for Nd3+ and Pr3+. For the Pr3+ ions strong the 1S0-1I6 transition has been recorded only for concentrated crystals. Efficient conversion of VUV excitation to UV-VIS emission was observed in crystals doped with 3 and 100 at% of cerium. In both cerium-activated crystals the lifetimes of f-d transitions were equal to 32 ns