Room temperature luminescence properties of Pr^{3 +} doped β-PbF₂ powders

Low cost cubic lead fluoride (β-PbF₂) is an attractive light-emitting material for dual readout purpose in homogeneous hadronic calorimeter (HHCAL), and introducing available scintillation light in PbF₂ is desperately needed. Among rare earth ions RE³⁺, Pr³⁺ ions usually show a unique fast and broad electric dipole allowed 5d–4f emission transition in luminescent inorganic materials. In this work, Pr³⁺ doped and Pr³⁺, Li⁺ co-doped β-PbF₂ powders of Pb_{1– x} Pr _x F_2+α (x = 0.1%, 0.5%, 1%, 3%, 5%) and Pb_{0.995– y} Pr_0.005Li _y F_2+β (y = 0.3%, 0.5%, 1%, 3%, 5%) were synthesized by solid state reaction in vacuum tube furnace to obtain a fast light. Typical 4f–4f emission transitions of Pr³⁺ ions were observed under ³H_4– ³P₂ excitation in Pb_{1– x} Pr _x F_2+β samples. Only 4f–4f emission transitions were observed under 4f–5d excitation because of the nonradiative relaxation of the 5d level into the lower 4f levels due to the low 4f–5d excitation transition energy (4.28 eV) of the Pr³⁺ ions in Pb_{1– x} Pr _x F_2+α samples. The co-doping of monovalent Li ions can increase the luminescent intensity of Pr³⁺ ions in PbF₂ host owing to the charge compensation. The decay time monitoring the 481 nm (under 4f–5d excitation) and 483 nm (under³H₄-³P₂ excitation) emission of Pr³⁺ ions in PbF₂ host is 17.5 and 24.9 μs, respectively.