Li 2 Ba 4 Al 2 Ta 2 N 8 O, the First Barium Nitridoalumotantalate with BCT-Zeolite Type Structure.

Single-crystals of Li 2 Ba 4 Al 2 Ta 2 N 8 O:Eu 2+ were synthesized from Ba 3 N 2 , Al 2 O 3 , Li 3 N, Eu 2 O 3 , and lithium metal by a high-temperature solid-state reaction in a weld shut tantalum ampule. The crystal structure of Li 2 Ba 4 Al 2 Ta 2 N 8 O was determined by single-crystal X-ray diffraction and it crystallizes in the orthorhombic space group Pnnm (no. 58) with the lattice parameters a=1006.71(3), b=1026.58(3), c=607.10(2) pm, and a volume of V=0.62742(3) nm 3 . The compound is built up from AlN 4 and TaN 4 tetrahedra, which form a three-dimensional network corresponding to the BCT-zeolite type structure. Li 2 Ba 4 Al 2 Ta 2 N 8 O is homeotypic to Li 2 Sr 4 Si 4 N 8 O and Li 2 Sr 4 Al 2 Ta 2 N 8 O but, additionally, it could be successfully doped with the activator ion Eu 2+ and hence features an experimental observed overall emission at λ max =565 nm (fwhm=89 nm) consisting of a superposition of two adjusted emission bands at λ max =557 nm (fwhm=69 nm) and at λ max =604 nm (fwhm=102 nm).