IMAGING THREE-DIMENSIONAL MESOCRYSTALLINE RUTILE NANOBALLS SYNTHESIZED BY THE RESIN-GEL METHOD

摘要

Self-assembled three dimensional rutile mesocrystalline particles are described in literature as hierarchical arrangements of rutile nanowires that align along in a common crystallographic manner. While there is a multitude of uses for mesoporous titania such as photocatalysis, water remediation and memristive switches; the mechanism of formation of these structures remains elusive. These 'nano-spiked-ball' arrangements have been successfully prepared using the resin-gel synthesis method. This method is based on the Pechini method for the synthesis of mixed metal oxides and involves the addition of a stable solution of metal ions to a coordinating polymer in a solvent matrix to form a polymeric resin. The working theory is that the metal ions are fixed in positions apart from each other until the reaction mixture is ignited to allow for agglomeration of the metal ions into nanoparticles. The resin-gel synthesis method affords the opportunity to synthesize different polymorphs - in the case of titania: anatase and rutile - that are stable at different energy minima and hence has the potential to become a powerful technique in future mixed-metal oxide syntheses. The aim of this study was to use TEM and HRTEM to image these resin-gel synthesized 3D hierarchical architectures and use the generated information to refine and enhance a previously described paradigm for the formation mechanism.