A Strontium Aluminosilicate SrAl₂SiO₆Offering a Scalable Route to Persistent Luminescent Materials

The substitution of silicon into SrAl₂O₄is of interest for the development of new persistent luminescence phosphors with complementary excitation and emission wavelengths, especially in the form of transparent ceramics or glass-ceramics by the glass-crystallization approach. Application of this approach to the series Sr_1–x/2Al_2–xSi_xO₄(0 ≤ x ≤ 1) has previously produced two different solid solutions adopting either the three-dimensional stuffed tridymite structure of SrAl₂O₄(0 ≤ x ≤ 0.5), or the two-dimensional hexacelsian structure of SrAl₂Si₂O₈(0.8 ≤ x ≤ 1.0), with a compositional gap between 0.5 < x < 0.8. Here, we synthesize a solid solution centered around SrAl₂SiO₆(x = 0.66), which is accessible in the range 0.60 ≤ x ≤ 0.75 by glass crystallization. The crystal structure of SrAl₂SiO₆features an aluminosilicate framework that is related topologically to SrAl₂O₄(stuffed tridymite) and also, more distantly, to SrAl₂Si₂O₈(hexacelsian), representing a stepwise reduction in framework dimensionality across the series. SrAl₂SiO₆exhibits an unusual pale blue-green persistent luminescence when doped with Eu²⁺/Dy³⁺, and can be produced as powders or transparent glass-ceramic disks. The pale afterglow color, transparency and scalability of these materials are complementary to the dominantly green persistent luminescence of SrAl₂O₄-based powders or single crystals.