Abstract
New experiments directly measure the rarely observed roughening of grain boundaries in a thin-film colloidal crystal and offer new insights into how polycrystals behave at high temperatures.
Highlights
Grain boundaries are the longest known but least understood crystal defects [1]
The inverse of the volume fraction φ−1 in colloids plays a similar role to effective temperature in atomic systems, and decreasing φ can drive the roughening of the grain boundary and crystal melting
We did not measure thick crystals with more than 30 layers because their grain boundaries often become curved along the z direction, which makes the dynamics of the whole grain boundary difficult to monitor
Summary
Grain boundaries are the longest known but least understood crystal defects [1]. They have significant effects on the properties of a broad class of polycrystalline materials, including metals, alloys, ceramics, minerals, magnets, and semiconductors [2]. Polycrystalline grains are usually faceted because some of the grain boundaries with certain angles have lower interfacial energy U than others. As temperature T increases, the entropy S becomes more important in the free energy of the grain boundary, F 1⁄4 U − TS.
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