1. Physics Department, University of Ioannina, GR-45110 Ioannina, Greece
2. Regional Centre of Advanced
Technologies and Materials, Faculty of Science, Departments of Physical
and Analytical Chemistry, Palacky University in Olomouc, 77146, Czech Republic
3. Department of Materials Science, University of Patras, 26504 Rio, Patras, Greece
4. Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United
States