Synthesis of perovskite-type LaWN3 by high-pressure solid-state metathesis reaction

Perovskite-type LaWN 3 was synthesized by the solid-state metathesis reaction of LaCl 3 , WCl 6, and Li 3 N under a pressure of 5 ​GPa and a temperature of 1573 ​K. The amount of oxygen in the synthesized sample is smaller than that in the sample prepared by the conventional ammonolysis of La 2 W 2 O 9 . The x-ray diffraction pattern of resulting phase can be fitted by either the meta-stable cubic structure with a P m 3 ¯ m space group or the ground-state rhombohedral structure with an R 3 c space group. The indirect bandgap of ∼1.2 ​eV and the direct band gap of ∼2.2 ​eV are consistent with those of the rhombohedral structure calculated by the density functional theory calculation with the HSE06 hybrid functional. High-pressure solid-state metathesis reaction yields perovskite-type LaWN 3 , unlike ambient pressure ammonolysis yields the oxynitride. • High-pressure synthesis of LaWN 3 binary nitride. • Solid-state metathesis (HPSSM) reaction of oxygen-free precursors. • Perovskite-type structure with pseudo-cubic symmetry. • Less residual oxygen compared to that in conventional oxynitrides. • Insulating/semiconducting nature with indirect band gap of ∼1.2 ​eV.