A novel class of oxynitrides stabilized by nitrogen dimer formation

Sangtae Kim, Hyo Jin Gwon, Sung Wook Paek, Seong Keun Kim, Ji Won Choi, Jin Sang Kim, Jung Hae Choi, Chong Yun Kang, Seung Hyub Baek

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Abstract

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.

Original languageEnglish
Article number14471
JournalScientific reports
Volume8
Issue number1
DOIs
Publication statusPublished - 2018 Dec 1

ASJC Scopus subject areas

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    Kim, S., Gwon, H. J., Paek, S. W., Kim, S. K., Choi, J. W., Kim, J. S., Choi, J. H., Kang, C. Y., & Baek, S. H. (2018). A novel class of oxynitrides stabilized by nitrogen dimer formation. Scientific reports, 8(1), [14471]. https://doi.org/10.1038/s41598-018-32909-x