Crystal Growth and Characterization of Rare Earth Doped ${\hbox {K}}_{3}{\hbox {LuF}}_{6}$

Transparent K₃LuF₆ single crystals doped with rare earth ions were successfully grown by the micro-pulling down method (μ-PD). X-ray diffraction measurements showed that the as-grown crystals possess monoclinic structure with P2₁/n space group. The radio- and photoluminescence spectra of the grown crystals were measured in the vacuum ultraviolet (VUV) and ultraviolet (UV) region. The intrinsic luminescence of K₃LuF₆ was observed at 163 and 200 nm. Nd-doped crystals displayed, in contrast, emission at 183 nm, due to the Nd³⁺ 5d-4f transition, and their radioluminescence intensity increases with increasing Nd concentration. Tm:K₃LuF₆ showed high emission intensity at 190 nm in the radio- and photoluminescence spectra (λ_exc = 155 nm). Moreover, the emission intensity of 0.5%Tm:K₃LuF₆ was higher than that of 5%Tm:K₃LuF₆. Concerning Er:K₃LuF₆, the emission at 165 nm was detected for the 0.5%Er:K₃LuF₆.