Comparative first-principles molecular dynamics study of TiN(001)/SiN/TiN(001) and TiN(001)/SiC/TiN(001) interfaces in superhard nanocomposites


I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Krzhizhanovsky str., 3, Kyiv, 03142, Ukraine
Proceedings of the 1st International Conference “Nanomaterials: Applications & Properties”, 2011, Т.1, #1


Heterostructures TiN(001)/SiN/TiN(001) and TiN(001)/SiC/TiN(001), with one monolayer (ML) of interfacial SiN and SiC, respectively, inserted between five monolayer thick B1-TiN, were investigated using first-principles quantum molecular dynamics (QMD) calculations. The temperature dependent QMD simulations at 300 K in combination with subsequent variable-cell structural relaxation revealed that the TiN(001)/SiN/TiN(001) interface exists as pseudomorphic B1-SiN layer only at 0 K, and as a superposition of distorted octahedral SiN6 and tetrahedral SiN4 units aligned along the (110) direction at a finite temperature. Thus, at 300 K, the interfacial layer is not epitaxial. Instead it consists of aggregates of the B1-SiN-like and Si3N4-like distorted clusters. However, in the the TiN(001)/SiC/TiN(001) heterostructures, the interfacial layer remains epitaxial B1-SiC at 0 K as well as at 300 K, with only a small shift of nitrogen atoms on both sides of the interface towards the silicon atoms. A comparison with the results obtained by earlier "static" ab initio DFT calculations at 0 K shows the great advantage of the QMD calculations that allow us to reveal structural reconstructions caused by thermal activation. When you are citing the document, use the following link