1. University of Lille-Sciences and Technologies, Unité Matériaux et Transformations(UMET)–CNRS UMR 8207, UFR de Physique, Bat P5, 59655 Villeneuve d'Ascq, France
2. Solid State Physics Section, Physics Department, National and Kapodistrian University of Athens, Panepistimiopolis, GR15784 Zogarfos, Athens, Greece
3. University of Science and Arts of Oklahoma, Chickasha, Oklahoma 73018, USA