DFG-Schwerpunktprogramm SPP1415

„Kristalline Nichtgleichgewichtsphasen (KNG) - Präparation, Charakterisierung und in-situ-Untersuchung der Bildungsmechanismen"

Investigation of the self-assembly and nucleation for metastable bismuth oxide polymorphs

A combined theoretical and experimental approach is envisaged to provide a detailed picture for the self-assembly of crystalline motifs and polymorphs of bismuth oxides. A promising approach to study the self-assembly process and the growth of Bi_xO_y species from solution is the "capture" of molecular bismuth oxido clusters with x + y = 5 to100 by addition of appropriate additives. Addition of these additives, which coordinate small bismuth-containing aggregates in solution, determines the particle formation and crystal growth at early stages. So far, the influence of the stabilizing ligands on the structure of small aggregates as well as on the formation of bismuth oxide polymorphs is not well understood. ESI-MS mass spectrometry offers the opportunity to study the nucleation process in situ and to evaluate the influence of the ligands e.g. by desolvation experiments for single aggregates. In addition to the experimental work molecular dynamic simulation is carried out to model the nucleation process. Only the combination of experiment and theory will provide a profound knowledge of the nucleation process and thus will help to identify bismuth oxido clusters that are promising precursors for the targeted synthesis of bismuth oxide polymorphs.