1. Fraunhofer Institute for Silicate Research ISC Neunerplatz 2 D‐97082 Würzburg Germany
2. Chair of Chemical Technology of Materials SynthesisDepartment Chemistry and PharmacyJulius‐Maximilians‐Universität Würzburg Röntgenring 11 D‐97070 Würzburg Germany
3. Institute of Particle TechnologyFriedrich‐Alexander‐Universität Erlangen‐Nürnberg Cauerstr. 4 D‐91058 Erlangen Germany
4. Interdisciplinary Center for Functional Particle SystemsFriedrich‐Alexander‐Universität Erlangen‐Nürnberg Haberstraße 9a D‐91058 Erlangen Germany
5. School of Mathematics and Physical SciencesUniversity of Hull Hull HU6 7RX UK