Aerosol Route as a Versatile Method for the Processing of Hierarchically Organized Hybrid Nano Particles

Abstract

Hierarchical structures, which refers to the materials that have more than one length scale, organized as the assemblage of primary units with high surface-to-volume ratio, play an important role in advanced materials design. Especially, the building of complex hierarchical structures exhibiting the hybrid organic-inorganic interfaces might be of special importance for the creation of advanced nanostructured materials having either improved or novel characteristics that bridges various scientific areas for the future diverse technological applications in catalysis, optics, energy, life science etc. Applying the bottom-up building blocks approaches, it is possible to create the hierarchical structures in a controlled manner having different morphologies, starting from aqueous, organic or colloidal precursor solutions. Among the diversity of the “bottom-up” chemical approaches, synthesis through dispersion phase (aerosol) enables generation of ultrafine, either single or complex structures with controlled stoichiometry, chemical and phase content. The opportunities of the hot wall aerosol processing, provided by high heating and cooling rates, short residence time and high surface reaction, refers to the synthesis of spherical three-dimensional (3D), hierarchically organized nanostructured particles with uniformly distributed components and phases. The particles composite inner structure, representing an assembly of nanosized primary particles, opens the possibility for particle surface modification and functionalization emphasizing their application in photovoltaics, energy transfer and bioimaging. This versatile technique has been used for the successful synthesis of hierarchically organized submicronic titanium (IV) oxide or Y2O3 up-conversion phosphor particles having the diverse levels of structural, morphological and functional complexity explored by means of appropriate selection of different precursor solutions, either true or colloid, surface modification and proper selection of rare-earth based dopants.