Role of the M choice in Hf(M)SiBCN (M = Y, Ho, Ta, Mo) thin films: DFT, ab initio molecular dynamics and experiment

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F49777513%3A23520%2F21%3A43962641" target="_blank" >RIV/49777513:23520/21:43962641 - isvavai.cz</a>

Alternative codes found

RIV/49777513:23640/21:43962641

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Role of the M choice in Hf(M)SiBCN (M = Y, Ho, Ta, Mo) thin films: DFT, ab initio molecular dynamics and experiment

Original language description

Thin films based on light main group elements are attractive due to a unique combination of properties ranging from high hardness through optical transparency to high temperature stability and oxidation resistance (up to 1500 °C). The properties, in the first place electrical conductivity, can be further modulated by addition of early transition metals. Properties of amorphous Hf(M)SiBCN films are investigated by combining static DFT calculations with ab initio molecular dynamics and their preparation using magnetron sputtering of composite B4C–Hf–M–Si targets in Ar + N2 reactive discharge gas. First, we study the effect of the M choice and fraction on calculated mechanical properties and formation energy of binary MN and ternary HfxM1–xN crystals. We discuss the dependence of formation energy on the crystal structure and on the distribution of Hf and M in the metal sublattice. The calculated mechanical properties of MN (rather than HfxM1–xN) very well correlate with measured mechanical properties of a-HfMSiBCN. The driving force towards N incorporation, monotonically decreasing with increasing periodic table group number of M according to the calculated formation energy of MN, very well correlates with measured electrical conductivity and extinction coefficient of a-HfMSiBCN. Second, we use Car–Parrinello molecular dynamics to model the a-HfMSiBCN materials of experimental compositions and densities themselves. The calculated band gap, localisation of states around the Fermi level and bonding preferences of the M atoms (in particular their tendency to bind with N atoms) also correlate with the measured increasing metallicity with respect to the periodic table group number of M and confirm the possibility of predicting the trends in characteristics of a-HfMSiBCN using those of MN. Third, we identify optimum target compositions (B4C covered by 15% Hf, 5% Ta and 15–20% Si) leading to hard (&gt;20 GPa) a-HfMSiBCN films with relatively high conductivity at a given extinction coefficient. The results are important for the design of hard, conductive and/or transparent high temperature coatings.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

20506 - Coating and films

Project

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Continuities

S - Specificky vyzkum na vysokych skolach

Publication year

2021

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů