Dependence of characteristics of MSiBCN (MÂ =Â Ti, Zr, Hf) on the choice of metal element: Experimental and ab-initio study

The paper deals with MSiBCN (M = Ti, Zr, Hf) thin films prepared by pulsed dc reactive magnetron sputtering of M15Si20(B4C)65 targets. We focus on the effect of M choice and N2 + Ar discharge gas mixture composition. The experimental results are complemented and explained by ab-initio calculations. We find that the transition from Ti through Zr to Hf leads to (i) increasing driving force towards segregation, (ii) weaker role of M around the Fermi level and opening of a wider band gap in N-rich compositions, (iii) higher electrical resistivity and lower extinction coefficient in N-rich compositions, (iv) increasing energy resulting from the oxidation of constituent M-containing phases, and consequently decreasing oxidation resistance of N-poor compositions and (v) increasing oxidation resistance of N-rich compositions. The results are important for the design of future coatings with tailored combinations of mechanical, electrical and optical properties and oxidation resistance.