Preparation and crystal structure of a new barium silicon nitride, Ba₅Si₂N₆

Abstract

Single crystals of a new ternary nitride, Ba₅Si₂N₆, were synthesized by slow cooling from 750°C using a starting mixture of Ba, Si, Na and NaN₃, where Na and NaN₃ were a flux and a nitrogen source respectively. It crystallizes with orthorhombic symmetry: space group $\text{P2}{}_1\text{2}{}_1\text{2}{}_1\text{(}\text{No.}\text{19), a = 6.159, b = 10.305, c = 15.292}\text{A}\text{̊}\text{,}\text{and}\text{Z = 4}$. The crystal structure was determined from single-crystal data and refined to R1 = 0.0495 for all 1637 observed reflections and 89 variables. A pair of SiN₄ tetrahedra contained in the structure forms a nitridometallate anion of [Si₂N₆]¹⁰ by edge sharing.