Synthesis and Structure of Two New Layered Ternary Nitrides, SrZrN₂ and SrHfN₂

The new ternary nitrides SrZrN₂ and SrHfN₂ have been synthesized by the solid state reactions of Sr₂N with ZrN and HfN and characterized by powder X-ray diffraction. Both nitrides form structures in the hexagonal space group A3̄m (SrZrN₂, a = 3.37302(5) Å, c = 17.6756(3) Å, Z = 3; SrHfN₂, a = 3.34481(3) Å, c= 17.6779(2) Å, Z = 3) and are isostructural with α-NaFeO₂. The structures are constructed of alternating layers of strontium-nitrogen edge-sharing octahedra and either zirconium-nitrogen or hafnium-nitrogen edge-sharing octahedra stacked along the c axis. Alternatively, Sr²⁺ can be regarded as occupying octahedral holes between Zr(Hf)N₂ octahedral layers. The title nitrides are essentially diamagnetic at room temperature, consistent with the chemical composition. These compounds are the first alkaline earth ternary nitrides observed to have the α-NaFeO₂ layered structure. 1 The University of Nottingham 2 The University of Birmingham.