Shape oscillations in growth of small crystals

The equilibrium shape of a large crystal is uniquely determined by the anisotropic surface energy. In sharp contrast, we show here that the equilibrium shape of a small crystal is not unique, for temperatures below the roughening temperature. Instead, the degree of faceting is an oscillatory function of crystal size. Using low-energy electron microscopy, we observe oscillations in the shape of silver crystallites as they grow; we demonstrate theoretically that such oscillations with size occur even in thermodynamic equilibrium. © 1993 The American Physical Society.