Shocks and curvature dynamics: A test of global kinetic faceting in crystals

We investigate the microscopic mechanisms underlying the dynamical faceting of crystals. Partially faceted crystal shapes of CCl4 are formed from a me lt contained in a Bridgman apparatus and pressure is used to control growth which is observed using optical microscopy. In contrast to predictions of models in which the local interfacial motion is greatest where the step den sity is the highest, the loss of rough orientations is observed to occur vi a a local decrease in curvature which results in the formation of discontin uities-shocks-in the surface of the growth forms, a feature predicted by a recent theory of kinetic faceting.