Na₂CaSn₂Ge₃O₁₂: A Novel Host Lattice for Sm³⁺-Doped Long-Persistent Phosphorescence Materials Emitting Reddish Orange Light

A novel host lattice disodium calcium ditin­(IV) trigermanium oxide Na₂CaSn₂Ge₃O₁₂ was utilized for synthesizing long-persistent phosphorescence materials for the first time. Reddish orange long-persistent phosphorescence was observed in Na₂CaSn₂Ge₃O₁₂:Sm³⁺ phosphors with persistence time more than 4.8 h. The phosphors were synthesized by a conventional solid-state reaction pathway in air atmosphere. A predominant cubic phase of Na₂CaSn₂Ge₃O₁₂ was observed in all XRD patterns. Photoluminescence measurements indicated that the emission spectrum was composed of the peaks located at 566 (the strongest), 605, 664, and 724 nm. The results of the decay curves in terms of a biexponential model suggest that different defects appear in the crystal lattice. The defects acting as traps were investigated by thermoluminescence, which demonstrated that doping Sm³⁺ ions into the Na₂CaSn₂Ge₃O₁₂ host has made the trap types abundant. Furthermore, the origin of the long-persistent phosphorescence has also been discussed. On the basis of the above results, Sm³⁺-doped Na₂CaSn₂Ge₃O₁₂ phosphors are considered to have potential practical applications

Enhancement of Light and X‑ray Charging in Persistent Luminescence Nanoparticle Scintillators Zn₂SiO₄:Mn²⁺, Yb³⁺, Li⁺

Persistent luminescence nanoparticle scintillators (PLNS) have been attempted for X-ray-induced photodynamic therapy (X-PDT) because persistent luminescence after ceasing radiation can make PLNS use less cumulative irradiation time and dose to generate the same amount of reactive oxygen species (ROS) compared with conventional scintillators to combat cancer cells. However, excessive surface defects in PLNS reduce the luminescence efficiency and quench the persistent luminescence, which is fatal to the efficacy of X-PDT. Herein, the PLNS of SiO2@Zn2SiO4:Mn2+, Yb3+, Li+ was designed by the energy trap engineering and synthesized by a simple template method, which has excellent X-ray and UV-excited persistent luminescence and continuously tunable emission spectra from 520 to 550 nm. Its luminescence intensity and afterglow time are more than 7 times that of the reported Zn2SiO4:Mn2+ used for X-PDT. By loading a Rose Bengal (RB) photosensitizer, an effective persistent energy transfer from the PLNS to photosensitizer is observed even after the removal of X-ray irradiation. The X-ray dose of nanoplatform SiO2@Zn2SiO4:Mn2+, Yb3+, Li+@RB in X-PDT of HeLa cancer cells was reduced to 0.18 Gy compared to the X-ray dose of 1.0 Gy for Zn2SiO4:Mn for X-PDT. This indicates that the Zn2SiO4:Mn2+, Yb3+, Li+ PLNS have great potential for X-PDT applications