Resolving the debated atomic structure of the metastable cubic SiNx tissue phase in nanocomposites with TiN

The TiN/SiNx nanocomposite and nanolaminate systems are the archetype for super if not ultrahard materials. Yet, the nature of the SiNx tissue phase is debated. Here, we show by atomically resolved electron microscopy methods that SiNx is epitaxially stabilized in a NaCl structure on the adjacent TiN(001) surfaces. Additionally, electron energy loss spectroscopy, supported by first-principles density functional theory calculations infer that SiNx hosts Si vacancies.Funding Agencies|Swedish Research Council (VR) [2008-405, 2012-4359, 2015-04391, 2016-04412]; Swedish Foundation for Strategic Research (SSF) through FunCase; SRL [10-0026]; M. Bergwall foundation; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; Ministry of Education and Science of the Russian Federation [14.Y26.31.0005, K2-2017-080]; [RIF 14-0074]