Enhanced Transparency through Second Phase Crystallization in BaAl4O7 Scintillating Ceramics

A series of biphasic (100 – z)­BaAl4O7–zBaAl2O4 (0 < z ≤ 45) transparent polycrystalline ceramics have been synthesized by full crystallization from glass process. Despite being composed of two birefringent crystalline phases, these new materials exhibit improved transparency compared to the pure BaAl4O7 ceramic recently reported to show remarkable scintillation properties. Multiscale structural characterizations demonstrate that this transparency enhancement can be explained by the presence of nanometer scale BaAl2O4 crystals which crystallize coherently with the BaAl4O7 matrix. We show that the BaAl2O4 nanostructuration limits the BaAl4O7 growth via an original Zener pinning effect, such decreasing light scattering due to the material birefringence. Interestingly, the BaAl4O7 scintillation properties can be retained in these two-phase transparent ceramics. These new materials, showing easier fabrication process, especially glass forming, could further drive the development of cost-effective scintillators.