Despite the wide applicability of oxynitrides from photocatalysis to refractory coatings, our understanding of the materials has been limited in terms of their thermodynamics. The configurational entropy via randomly mixed O/N or via cation vacancies are known to stabilize oxynitrides, despite the positive formation enthalpies. Here, using tin oxynitrides as a model system, we show by ab initio computations that oxynitrides in seemingly charge-unbalanced composition stabilize by forming pernitrides among metal-(O,N)6 octahedra. The nitrogen pernitride dimer, =(N-N)=, results in the effective charge of −4, facilitating the formation of nitrogen-rich oxynitrides. We report that the dimer forms only in structures with corner-sharing octahedra, since the N-N bond formation requires sufficient rotational degrees of freedom among the octahedra. X-ray photoemission spectra of the synthesized tin oxynitride films reveal two distinct nitrogen bonding environments, confirming the computation results. This work opens the search space for a novel kind of oxynitrides stabilized by N dimer formation, with specific structural selection rules.
CITATION STYLE
Kim, S., Gwon, H. J., Paek, S. W., Kim, S. K., Choi, J. W., Kim, J. S., … Baek, S. H. (2018). A novel class of oxynitrides stabilized by nitrogen dimer formation. Scientific Reports, 8(1). https://doi.org/10.1038/s41598-018-32909-x
Mendeley helps you to discover research relevant for your work.