Seed-Crystal-Induced Cold Sintering Toward Metal Halide Transparent Ceramic Scintillators

Scintillators with high spatial resolution at a low radiation dose rate are desirable for X-ray medical imaging. To challenge the state-of-art technology, it is necessary to design large-area wafers with high light yield, oriented light transport, and reduced light scattering. Here, a seed-crystal-induced cold sintering is adopted and a <001>-textured TPP₂ MnBr₄ (TPP: tetraphenylphosphonium) transparent ceramic is fabricated with a large-area wafer of 5 cm in diameter, exhibiting high optical transparency of above 68% over the 450-600 nm range. The compelling scintillation performance of the TPP₂ MnBr₄ wafer includes a light yield of ≈78 000 ± 2000 photons per MeV, a low detection limit 8.8 nanograys per second, about 625 times lower than the requirement of X-ray diagnostics (5500 nanograys per second), and an energy resolution of 17% for high-energy γ-rays (662 keV). X-ray imaging demonstrates a high spatial resolution of 15.7 lp mm^-1 . Moreover, the designed material exhibits good retention of the radioluminescence intensity and light yield. This work presents a paradigm for achieving light-guiding properties with high transparency and large-area fabrication by grain orientation engineering, and the transparent, textured metal halide ceramic scintillator is expected to provide a route for advancement in the X-ray imaging of tomorrow.