Supervisor: Dr. Laura Filion
Promotor: Prof. dr. ir. Marjolein Dijkstra
Funding: UU
Employed: 1 September 2014 – 31 August 2018

Defects in colloidal crystals

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. 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 defects in a range of colloidal crystals including hard cubes [1,2], hard spheres [3], binary mixtures of hard spheres [4,5], but also mixtures of active and passive particles [6,7]. These systems are ideal for this study as the defects are highly mobile. We expect our research to shed new light on defect diffusion 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.

[1] F. Smallenburg et al., PNAS 109, 17886 (2012)
[2] R. van Damme et al., JCP 147, 124501 (2017)
[3] B. van der Meer et al., JCP 146, 244905 (2017)
[4] L. Filion et al., PRL 107, 168302 (2011)
[5] B. van der Meer et al., JCP accepted (2017)
[6] B. van der Meer et al., Soft Matter 12, 3406 (2016)
[7] B. van der Meer et al., Soft Matter 12, 5630 (2016)