1. Department of Crystallography, Saint Petersburg State University, Universitetskaya Nab. 7/9, 199034 Saint Petersburg, Russia
2. Nanomaterials Research Center, Kola Science Center, Russian Academy of Sciences, 184200 Apatity, Murmansk Region, Russia
3. Leibniz Institute of Surface Modification, Permoserstrassse 15, D-04318 Leipzig, Germany