Oxygen-covered tungsten crystal shape: Time effects, equilibrium, surface energy and the edge-rounding temperature

The equilibrium crystal shape (ECS) of an oxygen-covered tungsten microcrystal is studied as a function of temperature. A specially designed ultrafast crystal quenching setup with the cooling rate of 6000 K/s allows to draw conclusions about ECS at high temperatures. The edge-rounding transition is shown to occur between 1300 K and 1430 K. The ratio of surface free energies γ(111)/γ(211) is determined as a function of temperature.