Equilibrium interfaces were established between body-centered cubic (BCC) crystals and their liquid using charged colloidal particles in an electric bottle. By measuring a time series of interfacial positions and computing the average power spectrum, their interfacial stiffness was determined according to the capillary fluctuation method. For the (100) and the (114) interfaces, the stiffnesses were 0.15 and 0.18
We study the kinetics of crystal growth and melting of two types of colloidal crystals: body-centered cubic (BCC) crystals and face-centered cubic (FCC) crystals. A dielectrophoretic “electric bottle” confines colloids, enabling precise control of the motion of the interface. We track the particle motion, and by introducing a structural order parameter, we measure the jump frequencies of particles to and from the crystal and determine from these the free-energy difference between the phases and the interface mobility. We find that the interface is rough in both BCC and FCC cases. Moreover, the jump frequencies correspond to those expected from the random walk of the particles, which translates to collision-limited growth in metallic systems. The mobility of the BCC interface is greater than that of the FCC interface. In addition, contrary to the prediction of some early computer simulations, we show that there is no significant asymmetry between the mobilities for crystallization and melting.
more » « less- NSF-PAR ID:
- 10082868
- Publisher / Repository:
- Proceedings of the National Academy of Sciences
- Date Published:
- Journal Name:
- Proceedings of the National Academy of Sciences
- Volume:
- 116
- Issue:
- 4
- ISSN:
- 0027-8424
- Page Range / eLocation ID:
- p. 1180-1184
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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(σ: particle diameter), respectively, and were isotropic in the plane of the interface. For comparison, similar charged colloids were used to create an interface between a face-centered cubic (FCC) crystal and its liquid. Its stiffness was significantly larger: 0.26 . This result gives experimental support to the explanations offered for the preferential nucleation of BCC over FCC in metallic alloys. -
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