Dresden 2011 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MM: Fachverband Metall- und Materialphysik

MM 45: Topical Session Heterogeneous Nucleation II

MM 45.3: Vortrag

Freitag, 18. März 2011, 11:00–11:15, IFW B

(contribution withdrawn) Homogeneous Nucleation and Crystal Crowth of Metallic Nanoparticle Superstructures — •Philip Born and Tobias Kraus — Leibniz-Institut for Neue Materialien (INM), Saarbrücken, Deutschland

The various interparticle interactions in nanoparticle suspensions lead to a phase diagram which is akin the thermodynamic phase diagram of atomic gases. In the atomic-gas-like state of colloidal suspensions, assembly is driven by the strength and directionality of the interparticle potentials, whose range is large compared to the particle size. The phase diagram alters drastically when the ratio between the particle size and the range of the interparticle forces increases. The liquid phase vanishes with increasing ratio, and the system eventually exhibits the temperature-independent jamming phase diagram of macroscopic granular media.

Here, we use sterically stabilized gold nanoparticles as a model system to explore experimentally the thermodynamic concentration-temperature (c-T) phase diagram of a colloidal suspension. We focus on the ordering of the emerging superstructures after quenching the system to the instable regime. By exchanging the capping layer of the gold particles the ratio between particle size and interaction potential range and the interactions among the ligand shells of particles can be changed. By systematically increasing the capping layer thickness, the transition from a rather atom-like to a granular media-like state can be observed. The interactions among the ligand shells of the particles change the interparticle friction and inhibit rearrangement.