High-Pressure High-Temperature Synthesis of Mixed Nitridosilicatephosphates and Luminescence of AESiP3N7:Eu2+ (AE = Sr, Ba).

Tetrahedra based nitrides with network structures have emerged as versatile materials with a broad spectrum of properties and applications. Both nitridosilicates and nitridophosphates are well-known examples of such nitrides which upon doping with Eu 2+ exhibit intriguing luminescence properties that make them attractive for applications. Nitridosilicates and nitridophosphates show manifold structural variability, however, no mixed nitridosilicatephosphates except SiPN 3 and SiP 2 N 4 NH have been described so far. The compounds AE SiP 3 N 7 ( AE = Sr, Ba) were synthesized by a high-pressure high-temperature approach using the multianvil technique (8 GPa, 1400 - 1700 °C) starting from the respective alkaline earth azides and the binary nitrides P 3 N 5 and Si 3 N 4 . The latter were activated by NH 4 F, probably acting as a mineralizing agent. SrSiP 3 N 7 and BaSiP 3 N 7 were obtained as single crystals. They crystallize in the barylite-1 O ( M = Sr) and barylite-2 O structure types ( M = Ba), respectively, with P and Si being occupationally disordered. Cation disorder is further supported by solid-state NMR and EDX mapping of BaSiP 3 N 7 with atomic resolution. Upon doping with Eu 2+ , both compounds show blue emission under UV excitation.