Surface Work Functions Of AlCu₃ And Fcc Metals From First-Principles Study

At present, the domestic and foreign investigations of work function (WF) change for binary alloys under different stress or strain state were mainly performed by the experimental methods, and few theoretical studies were reported. Moreover, owing to the limitations of the experimental methods, people could not successfully interpret the physical mechanism of the WF change. In order to fully understand the effects of strain on the WF, first-principles calculations were performed to systematically study the effects of biaxial strain on the WF of AlCu₃. In addition, stacking faults have important impact on the surface WF, but the related studies are very few. Therefore, the effects of intrinsic stacking fault on the WF of ( 1 10) surface for metals with face centered cubic (fcc) structure were studied by first-principles calculations. The main contents are listed as follows:1. First-principles calculations were performed to study the surface energy, WF and the effects of biaxial strain on the WF of the (001), (110) and (111) surfaces of AlCu₃. Moreover, relationships among the WF change, atomic relaxation and the charge transfer were discussed. The calculated results showed that the surface formed by Al and Cu had a lower surface energy and was a stable surface structure. The WF of the stable surfaces of AlCu₃ follows the rule that WF of the high density packed plane is larger than the WF of the low density packed plane. Tensile strain decreased the WF, while compressive strain increased the WF. Under strain condition, a larger surface atomic relaxation often induced a larger WF change.2. First-principles calculations were performed to study the effects of intrinsic stacking fault on the WF and surface energy of ( 1 10) surface of fcc metals. A simple rule was summarized based on the calculated results. When listing the variation of the WF in the form of periodic table, trends occured in the same group but not for the same period. For example, the WF decreased for the metals of IA, IIA, IIIA, IIIB and VIIB group. While for the metals Co and Rh, Ni and Pd of VIII group, Cu and Ag of IB group and Pb of IVA group, the WF all increased. But the variation of WF for the metals of IVB group and the first column of VIII group showed no trend. However, regarding 26 kinds of metals, we found that the surface energy of ( 1 10) decreased except Mn, Fe, Tc, Ru, Hf, Re and Os when existing the stacking fault.