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 Sm 3+ and Sm 2+ ions. Sm‐doped FCZ‐GCs have been prepared by annealing a ZBLAN glass of nominal composition 53% ZrF 4 , 20% NaF, 3% AlF 3 , 3% LaF 3 , 1% SmF 3 , 1% BaF 2 , 19% BaCl 2 (mol%) above the glass transition of the host glass matrix. SmF 3 was added to the initial glass mix for trivalent samarium doping. Sm 2+ doping was achieved by reducing Sm 3+ to Sm 2+ during the melting of the initial mix by the addition of NaBH 4 . FCZ‐GC contains BaCl 2 nanocrystals formed during the annealing with embedded Sm 2+ ions, which dominate PL and XL. The PL of Sm 2+ ions embedded in BaCl 2 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 <∼30 nm are mainly hexagonal while larger crystals are mostly orthorhombic. XL is more efficient in glass–ceramics containing relatively large BaCl 2 nanocrystals with hexagonal crystal structure.