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arXiv · 1504.06047

The origin of anomalous diffusion in iron mononitride thin films

Akhil Tayal·Mukul Gupta·Ajay Gupta·P. R. Rajput·J. Stahn
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Abstract

We have studied the origin of a counter intuitive diffusion behavior of Fe and N atoms in a iron mononitride (FeN) thin film. It was observed that in-spite of a larger atomic size, Fe tend to diffuse more rapidly than smaller N atoms. This only happens in the N-rich region of Fe-N phase diagram, in the N-poor regions, N diffusion coefficient is orders of magnitude larger than Fe. Detailed self-diffusion measurements performed in FeN thin films reveal that the diffusion mechanism of Fe and N is different - Fe atoms diffuse through a complex process, which in addition to a volume diffusion, pre-dominantly controlled by a fast grain boundary diffusion. On the other hand N atoms diffuse through a classical volume-type diffusion process. Observed results have been explained in terms of stronger Fe-N (than Fe-Fe) bonds generally predicted theoretically for mononitride compositions of transition metals.

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Akhil Tayal, Mukul Gupta, Ajay Gupta, P. R. Rajput, J. Stahn. 2015-04-23. The origin of anomalous diffusion in iron mononitride thin films. https://doi.org/10.1103/physrevb.92.054109

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