Preparation via the polymer route and photoluminescence properties of CeSi3N5

CeSi₃N₅ has been prepared via the polymer route, a one-pot and liquid-phase synthesis, based on a reaction between SiCl₄ and liquid NH₃ in which Ce[N(Si(CH₃)₃)₂]₃ was suspended. The sample was characterized by powder X-ray diffraction analysis, diffuse reflection and photoluminescence spectroscopies. CeSi₃N₅ exhibits a strong absorption peaking at 365 nm. Furthermore, it has a broad emission band at 468 nm due to 4f⁰5d¹ → 4f¹ transition of Ce³⁺. Obviously, CeSi₃N₅ appears to be a good candidate for use as a blue phosphor, which can be pumped by near-UV-LEDs.     

Li4Ca3Si2N6 and Li4Sr3Si2N6 – Quaternary Lithium Nitridosilicates with Isolated [Si2N6]10– Ions

The isotypic nitridosilicates Li₄Ca₃Si₂N₆ and Li₄Sr₃Si₂N₆ were synthesized by reaction of strontium or calcium with Si(NH)₂ and additional excess of Li₃N in weld shut tantalum ampoules. The crystal structure, which has been solved by single‐crystal X‐ray diffraction (Li₄Sr₃Si₂N₆: C2/m, Z = 2, a = 6.1268(12), b = 9.6866(19), c = 6.2200(12) Å, β = 90.24(3)°, wR₂ = 0.0903) is made up from isolated [Si₂N₆]^10– ions and is isotypic to Li₄Sr₃Ge₂N₆. The bonding angels and distances within the edge‐sharing [Si₂N₆]^10– double‐tetrahedra are strongly dependent on the lewis acidity of the counterions. This finding is discussed in relation to the compounds Ca₅Si₂N₆ and Ba₅Si₂N₆, which also exhibit isolated [Si₂N₆]^10– ions.