1. Department of Materials Science and Engineering, University of Ioannina, GR-451 10 Ioannina, Greece
2. Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, N. Plastira 100, Vasilika Vouton, GR-700 13 Heraklion-Crete, Greece
3. Centre of Advanced Materials, Department of Mechanical Engineering, Universiti Malaya, Kuala Lumpur 50603, Malaysia