1. Department of Physical ChemistryUniversity of P.J. Šafárik in Košice Moyzesova 11 040 01 Košice Slovakia
2. Institute of ElectrotechnologyTechnical University of Brno Technická 10 Brno 602 00 Czech Republic
3. Institute of Materials ResearchSlovak Academy of Sciences Watsonova 47 040 01 Košice Slovakia