1. IENI-CNR, Via De Marini 6, I-16149 Genoa, Italy
2. Department of Physics, Alexandru Ioan Cuza University, Bulevardul Carol I, Nr. 11, Iasi 700506, Romania
3. Department of Science & Engineering of Oxide Materials, Polytechnic University of Bucharest, 1-7 Gh. Polizu, P.O. Box 12-134, 011061 Bucharest, Romania
4. Department of Materials and Environmental Chemistry, University of Stockholm, SE-10691, Stockholm, Sweden
5. Department of Process and Chemical Engineering, University of Genoa, Fiera del Mare, Pad. D, I-16129 Genoa, Italy