1. Institute of Inorganic Chemistry, Technology and Materials, Slovak University of Technology in Bratislava, Radlinského 9, 812 37 Bratislava, Slovakia
2. Slovak Academy of Science, Institute of Materials Research, Watsonova 5, 040 01 Košice, Slovakia
3. Institute of Electrical Engineering, Slovak University of Technology in Bratislava, Dúbravská cesta 5, 8410 04 Bratislava, Slovakia