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 P212121 (No. 19), a = 6.159, b = 10.305, c = 15.292 Å, and 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.