1. G. V. Kurdyumov Institute for Metal Physics 1 , NAS of Ukraine, Kyiv 03142, Ukraine
2. V. Bakul Institute for Superhard Materials 2 , NAS of Ukraine, Kyiv 07074, Ukraine
3. Taras Shevchenko National University of Kyiv 3 , Kyiv 01033, Ukraine
4. Kyiv Academic University 4 , Kyiv 03142, Ukraine