Observation of vertex-rounding transition for a crystal in equilibrium: Oxygen-covered tungsten, A. Szczepkowicz, R. Bryl, Phys. Rev. B. 71 (2005) 113416.

Equilibrium crystal shape of oxygen-covered tungsten is followed as a function of temperature using field ion microscopy. In the vicinity of the (111) region, at the temperature 970+-70~K, the system undergoes a phase transition from a polyhedral form (sharp edges and sharp vertex) to a rounded form (sharp edges, rounded vertex).

68.35.Md  Surface thermodynamics, surface energies
68.60.Dv  Thermal stability; thermal effects
68.37.Vj  Field emission and field-ion microscopy

Surface topography, Equilibrium thermodynamics and statistical mechanics, Faceting, Tungsten, Oxygen, Single crystal surfaces, Curved surfaces, Field ion microscopy