Shear melting of a hexagonal columnar crystal by proliferation of dislocations.
A hexagonal columnar crystal undergoes a shear-melting transition above a critical shear rate or stress. We combine the analysis of the shear-thinning regime below the melting with that of synchrotron x-ray scattering data under shear and propose the melting to be due to a proliferation of dislocations, whose density is determined by both techniques to vary as a power law of the shear rate with a 2/3 exponent, as expected for a creep model of crystalline solids. Moreover, our data suggest the existence under shear of a line hexatic phase, between the columnar crystal and the liquid phase.
Ramos
Laurence
L
Groupe de Dynamique des Phases Condensées (UMR CNRS-UM2 5581), CC26, Université Montpellier 2, 34095 Montpellier CEDEX 5, France. ramos@gdpc.univ-montp2.fr
Molino
François
F