杂质对吸附系统O/RhxPt1-x衬底合金(110)表面偏析的影响

The influence of impurities on segregation of the(110) surfaceof O/Rh_xPt_(1-x) alloy system

构造了考虑吸附与偏析相互作用情况下无序二元合金RhxPt1-x(110)吸附氧表面的原子集团模型,其中O的覆盖度为0.5;构造了考虑杂质Ni,Cu,W对合金可能产生影响的吸附表面原子集团模型,杂质的掺入采用替位式.应用recursion方法计算了合金表面的环境敏感镶嵌能和电子结构.环境敏感镶嵌能计算表明杂质Ni,Cu和W均使O吸附RhxPt1-x(110)合金表面偏析情况发生逆转,Ni对Rh-Pt合金偏析的影响最大,其次是Cu,W对合金偏析的影响最小;电子结构计算表明杂质Ni,Cu,W存在于合金表面时,使Rh与O的共价相互作用减弱,使表面偏析发生逆转,Pt再次偏析于表面.

The atomic cluster models of （110） surface of Rh, Pt1 _ x disordered binary alloy were constructed under the condition that there is interaction between adsorption and segregation. The coverage of O is 0.5. Also, the models that may have an impact on the alloy debased with Cu, Ni and W were set up by computer respectively. It followed that impurities replaced every Rh which should be the nearest neighbor of O. The environment sensitive inlaid energy （ EKSE ） and the electronic structure of the alloy surface doped with Cu, Ni and W was calculated by recursion method. The results of EESE show that, the influence of Ni, Cu and W on Rh-Pt alloy are all to reverse the segregation of the alloy surface. Furthermore, Ni is the most effective imupurity, and then Cu and W. Doped with impurities Cu, Ni and W, the covalent interaction between Rh and O is reduced, which reverses the surface segregation, so Pt segregates on the surface.