Li2 Ba4 Al2 Ta2 N8 O, the First Barium Nitridoalumotantalate with BCT-Zeolite Type Structure.

Abstract

Single-crystals of Li2 Ba4 Al2 Ta2 N8 O:Eu2+ were synthesized from Ba3 N2 , Al2 O3 , Li3 N, Eu2 O3 , and lithium metal by a high-temperature solid-state reaction in a weld shut tantalum ampule. The crystal structure of Li2 Ba4 Al2 Ta2 N8 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) nm3 . The compound is built up from AlN4 and TaN4 tetrahedra, which form a three-dimensional network corresponding to the BCT-zeolite type structure. Li2 Ba4 Al2 Ta2 N8 O is homeotypic to Li2 Sr4 Si4 N8 O and Li2 Sr4 Al2 Ta2 N8 O but, additionally, it could be successfully doped with the activator ion Eu2+ and hence features an experimental observed overall emission at λmax =565 nm (fwhm=89 nm) consisting of a superposition of two adjusted emission bands at λmax =557 nm (fwhm=69 nm) and at λmax =604 nm (fwhm=102 nm).