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SURFACE SELF-DIFFUSION ANISOTROPY OF TUNGSTEN ATOMS ON W(112) PLANE |
| GONG Yunming |
| Department of Radio-Electronics, Peking University, Beijing 100871 |
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| Cite this article: |
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GONG Yunming 1990 Chin. Phys. Lett. 7 537-540 |
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Abstract Surface self-diffusion anisotropy of tungsten on W(112) plane has been measured along (||) and across (⊥) channels existed on this plane by using the field emission fluctuation method in two forms of the probeholes. In the round probehole the thermal activation energy E=13.0kcal, and the prefactor of the surface self-diffusion coefficient D0 = 4.8x10-7 cm2 s-1; in the long narrow rectangular slit, E(||) =13.2kcal, D0(||)= 7.1x10-7 cm2 s-1 and E (⊥) =6.2kcal, D0(⊥) =1.8X 10-9 cm2 s-1 at T=500～700K. The experimental data suggest that a W atom diffusing across channels should not climb over the channel wall, which would certainly require a much higher activation energy, but instead, displace an atom in the wall. This process requires a much smaller activation energy; however, since it involves concerted motion of at least two atoms, it will also have a much smaller prefactor.
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| Keywords:
07.80.+x
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Published: 01 December 1990
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