1. Lviv Polytechnic National University, 12 Bandera St., 79013 Lviv, Ukraine
2. Institute of Physics, Rzeszow University, 16a Rejtana St., 35‐310 Rzeszow, Poland
3. Ternopil State Technical University, 56 Russka St., 46001 Ternopil, Ukraine
4. R & D Institute for Materials SRC “Carat”, 202 Stryjska St., 79 031 Lviv, Ukraine