1. Department of Inorganic Chemistry, Escuela de Ingenierías Industriales, University of Valladolid, Paseo del Cauce, 59, 47011 Valladolid, Spain
2. Department of Chemistry, Physics and Environment, Faculty of Sciences and Environment, "Dunarea de Jos", University of Galati, 47 Domneasca Street, 800008 Galati, Romania
3. Department of Condensed Matter Physics, Faculty of Sciences, University of Valladolid, 47011 Valladolid, Spain