Scanning Microscopy


Measurements of surface self-diffusion by the field emission fluctuation method along the zones (011)-(112) and (011)-(001) of a tungsten emitter show both 2 and I dimensional diffusion, attributed to diffusion of W atoms on the terraces and of kinks along the edges of the stepped surfaces found in these zones. At 950 K -1000 K the steps along (011)-(112) disorder completely, as indicated by the merging of the two types of diffusion into a single, 2-dimensional regime. Along (011)-(001) definite transitions can only be seen on (023) and (017). The transition temperatures are much lower, ~750 K.

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