Crystal growth, Nd distribution and luminescence properties of (Na _0.425xLu_0.575-x-yNd_y)F_2.15-2x single crystals

(Na_0.425xLu_0.575-x-yNd_y)F _2.15-2x (x=0, y=0, 0.001, 0.01, 0.05, 0.1, 0.2; x=±0.01, 0.02, 0.05, y=0.05) single crystals were grown from the melt using the precise atmosphere control type Micro-Pulling-Down (μ-PD) method to examine their potential as a new VUV scintillators. The grown crystals were single-phase materials with fluorite type structure (Fm-3m, Z=4) as confirmed by XRD and had good crystallinity. The distribution of the crystal constituents in axial and radial directions was evaluated, and only negligible non-uniformity along growth axis was detected. The crystals demonstrated 7090% transmittance above 176188 nm wavelength and Nd³ 5d4f luminescence (when exited by X-ray) observed around 185 nm. Both 5d4f absorption and emission peaks shifted to longer wavelength region. The radioluminiscence measurements under 5.5 MeV α-ray excitation (²⁴¹Am) demonstrated the light yield of 3590 [Ph/5.5 MeV-α] and the decay time of 5.57.5 ns.