TY - JOUR
T1 - Hexatic-to-disorder transition in colloidal crystals near electrodes
T2 - Rapid annealing of polycrystalline domains
AU - Dutcher, C. S.
AU - Woehl, T. J.
AU - Talken, N. H.
AU - Ristenpart, W. D.
PY - 2013/9/19
Y1 - 2013/9/19
N2 - Colloids are known to form planar, hexagonal closed packed (hcp) crystals near electrodes in response to electrohydrodynamic (EHD) flow. Previous work has established that the EHD velocity increases as the applied ac frequency decreases. Here we report the existence of an order-to-disorder transition at sufficiently low frequencies, despite the increase in the attractive EHD driving force. At large frequencies (∼500 Hz), spherical micron-scale particles form hcp crystals; as the frequency is decreased below ∼250 Hz, however, the crystalline structure transitions to randomly closed packed (rcp). The transition is reversible and second order with respect to frequency, and independent measurements of the EHD aggregation rate confirm that the EHD driving force is indeed higher at the lower frequencies. We present evidence that the transition is instead caused by an increased particle diffusivity due to increased particle height over the electrode at lower frequencies, and we demonstrate that the hcp-rcp transition facilitates rapid annealing of polycrystalline domains.
AB - Colloids are known to form planar, hexagonal closed packed (hcp) crystals near electrodes in response to electrohydrodynamic (EHD) flow. Previous work has established that the EHD velocity increases as the applied ac frequency decreases. Here we report the existence of an order-to-disorder transition at sufficiently low frequencies, despite the increase in the attractive EHD driving force. At large frequencies (∼500 Hz), spherical micron-scale particles form hcp crystals; as the frequency is decreased below ∼250 Hz, however, the crystalline structure transitions to randomly closed packed (rcp). The transition is reversible and second order with respect to frequency, and independent measurements of the EHD aggregation rate confirm that the EHD driving force is indeed higher at the lower frequencies. We present evidence that the transition is instead caused by an increased particle diffusivity due to increased particle height over the electrode at lower frequencies, and we demonstrate that the hcp-rcp transition facilitates rapid annealing of polycrystalline domains.
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U2 - 10.1103/PhysRevLett.111.128302
DO - 10.1103/PhysRevLett.111.128302
M3 - Article
C2 - 24093305
AN - SCOPUS:84884689971
SN - 0031-9007
VL - 111
JO - Physical review letters
JF - Physical review letters
IS - 12
M1 - 128302
ER -