Chemists at the Department of Materials and Environmental Chemistry at Stockholm University in Sweden, together with colleagues at the MAX IV Laboratory in Lund, have studied how nanoparticles self-assemble. By using synchrotron radiation at MAX IV Laboratory in Lund, they are able to follow how nanocubes come together and form large and ordered structures inside drops that are levitated in an acoustic field. They show that the crystallization process proceeds in two stages involving the formation and rapid transformation of a dense, structurally disordered phase into ordered mesocrystals.
Mesocrystals composed of crystallographically aligned nanocrystals are of great importance for mechanical protection in shells and bones. Mesocrystals are commonly formed by complex biomineralization processes that are only partly understood.
“The discovery that the formation of artificial mesocrystals proceeds through a two-step process where nanoparticles first agglomerate into an intermediate disordered precursor that then rapidly transforms into large, ordered mesocrystals is similar to what has been recently observed for many synthetic crystal and biominerals” says Germán Salazar-Álvarez, docent at the Department of Materials and Environmental Chemistry at Stockholm University.
The researchers believe that their results could pave the way to produce new materials with unique functions that exploit the order at the mesoscale. Mesocrystals composed of crystallographically aligned polyhedral or rod-like nanocrystals with anisotropic properties can yield materials with strongly directional and collective properties.
The research results have been published in the scientific journal Nano Letters.
Agthe, M et al (2016). Following in Real Time the Two-Step Assembly of Nanoparticles into Mesocrystals in Levitating Drops, Nano Letters DOI: 10.1021/acs.nanolett.6b02586
Researchers at the Department of Chemistry, Stockholm University
Researchers at MAX IV Laboratory