Berend van der Meer MSc
Ornstein Laboratory, room 58
Princetonplein 1, 3584 CC Utrecht
P.O. Box 80 000, 3508 TA Utrecht
phone: +31(0)30 253 2344
secretariat: +31(0)30 253 2952
Supervisor: Dr. L.C. Filion
Promotor: Prof.dr.ir. M. Dijkstra
Employed since September 2014
Funded by Sectorplan UU
Particles in a crystal phase are typically orders of magnitude less mobile than those in a fluid phase. Nonetheless, particles in a crystal can diffuse via the motion of defects, such as vacancies and interstitials. The motion of these defects plays an important role in the transport and mechanical properties of materials, and are a crucial factor for mechanical instabilities such as creep, yield, and fracture. Additionally, the diffusion of foreign species of particles through a crystal can be used to change its properties. This can be be used to introduce dopant atoms into semiconductors, or even to fully exchange one type of ion for another in nanoparticles. However, while these defects are clearly important for material properties, little is known about the dynamics of defects in colloidal crystals.
In this project, we use computer simulations to investigate defect dynamics in a range of colloidal crystals including hard cubes (see Figure 1) , two-dimensional soft repulsive crystals and binary mixtures . These systems are ideal for this study as the defects are highly mobile. We expect our research to shed new light on diffusion and particle exchange in crystalline solids.
Figure 1: (a) Crystal of hard cubes containing many extended vacancy defects. (b) Visualization of these delocalized vacancies in the crystal. The particles that are part of the vacancy are displayed at their original size, while others are displayed much smaller.
 F. Smallenburg et al., PNAS 109, 17886 (2012)
 L. Filion et al., PRL 107, 168302 (2011)