1. Materials Science Department, Technische Universität Darmstadt, 64287 Darmstadt, Germany
2. Ceramics Laboratory, École Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland
3. Institute of Physical Chemistry I, Universität Freiburg, 79104 Freiburg, Germany
4. Division of Electronic Engineering and Physics, University of Dundee, Dundee DD1 4HN, United Kingdom
5. School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 689-798, South Korea
6. Centre de Recherche Public—Gabriel Lippmann, L-4422 Belvaux, Luxembourg