Synthesis and Comprehensive Studies of Be-IV-N 2 (IV=Si, Ge): Solving the Mystery of Wurtzite-Type Pmc2 1 Structures.

The research for wurtzite-type ternary nitride semiconductors containing earth abundant elements with a stoichiometry of 1 : 1 : 2 was focused on metals like Mg or Zn, so far. The vast majority of these Grimm-Sommerfeld analogue compounds crystallize in the β-NaFeO 2 structure, although a second arrangement in space group Pmc2 1 is predicted to be a viable alternative. Despite extensive theoretical and experimental studies, this structure has so far remained undiscovered. Herein, we report on BeGeN 2 in a Pmc2 1 structure, synthesized from Be 3 N 2 and Ge 3 N 4 using a high-pressure high-temperature approach at 6 GPa and 800 °C. The compound was characterized by powder X-ray diffraction (PXRD), solid state nuclear magnetic resonance (NMR), Raman and energy dispersive X-ray (EDX) spectroscopy, temperature-dependent PXRD, second harmonic generation (SHG) and UV/Vis measurements and in addition also compared to its lighter homologue BeSiN 2 in all mentioned analytic techniques. The synthesis and investigation of both the first beryllium germanium nitride and the first ternary wurtzite-type nitride crystallizing in space group Pmc2 1 open the door to a new field of research on wurtzite-type related structures.