Samarium-Doped Fluorochlorozirconate Glass-Ceramics as Red-Emitting X-Ray Phosphors

We have examined the photoluminescence (PL) and X‐ray luminescence (XL) of fluorochlorozirconate (FCZ) glass–ceramics (FCZ‐GC) doped with Sm3+ and Sm2+ ions. Sm‐doped FCZ‐GCs have been prepared by annealing a ZBLAN glass of nominal composition 53% ZrF4, 20% NaF, 3% AlF3, 3% LaF3, 1% SmF3, 1% BaF2, 19% BaCl2 (mol%) above the glass transition of the host glass matrix. SmF3 was added to the initial glass mix for trivalent samarium doping. Sm2+ doping was achieved by reducing Sm3+ to Sm2+ during the melting of the initial mix by the addition of NaBH4. FCZ‐GC contains BaCl2 nanocrystals formed during the annealing with embedded Sm2+ ions, which dominate PL and XL. The PL of Sm2+ ions embedded in BaCl2 nanocrystals strongly depends on their crystal structure (hexagonal or orthorhombic) and may be used to identify that structure. The correlation of the PL spectra with X‐ray diffraction data is used to estimate the size of nanocrystals. The nanocrystals with average dimensions