Reddish Orange Long-Lasting Phosphorescence in KY₃F₁₀:Sm³⁺ for X-Ray or Cathode Ray Tubes

We report a reddish orange long-lasting phosphor of KY₃F₁₀:Sm³⁺ synthesized by a solid−state reaction for applications in x-ray or cathode-ray tubes. The spectrum contains a group of reddish orange emission lines originating from ⁴G_5/2→⁶H_J transitions of Sm³⁺. The Judd–Ofelt theory is introduced to analyze the optical transitions of the Sm³⁺ ions. Moreover, phosphorescence characteristics are discussed. The energy charging and release processes of the phosphor are measured and the phosphorescence decay time with 10% of initial intensity is about 40.7 seconds. The order of kinetics and the activation energy are obtained according to the thermoluminescence curve. The phosphorescence mechanism is proposed based on structural analysis and thermoluminescence glow curve measurement.