Atomic jumps in surface self-diffusion: W on W(110)

Although surface diffusion has been studied on the atomic level for decades, little is known about jump processes in self-diffusion. The diffusion of W atoms on the densely packed W(110) plane has therefore been examined, using the field ion microscope to probe contributions of jumps other than between nearest-neighbor sites. Measurements of the mean-square displacements of atoms along the x and y axes (<001> and <110>, respectively) and of the detailed spatial distribution of atomic displacements serve to define the nature of the jumps important in diffusion. It is shown that, in addition to nearest-neighbor and second-nearest-neighbor transitions along the close-packed <111>, atoms also carry out jumps along <001> and <110>, and that the contribution from these processes increases rapidly with temperature.