SURFACE SEGREGATION OF BA IN MGO
Surface segregation of Ba in doped polycrystalline and single crystal MgO has been studied by XPS. There is little variation in surface coverage of Ba over a range of bulk doping levels from 7 to 7000 ppm in ceramic pellets equilibrated at 1630 K. This remarkable behaviour is shown to be consistent...
| Main Authors: | , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
1989
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| Summary: | Surface segregation of Ba in doped polycrystalline and single crystal MgO has been studied by XPS. There is little variation in surface coverage of Ba over a range of bulk doping levels from 7 to 7000 ppm in ceramic pellets equilibrated at 1630 K. This remarkable behaviour is shown to be consistent with surface coverage calculated from heats of segregation derived from ionic model simulations of the surface if due account is taken of the strong variation of the segregation energy with coverage. The coverage of Ba on a MgO(001) single crystal surface doped by indiffusion of Ba deposited onto the crystal from a getter source can be made similar to that of the polycrystalline material. The Ba-segregated MgO(001) surface exhibits a complex LEED pattern. © 1989. |
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