Acta Metall Sin  2020, Vol. 56 Issue (6): 919-928    DOI: 10.11900/0412.1961.2019.00411
 Current Issue | Archive | Adv Search |
Effects of Alloying Elements on the Adsorption of Oxygen on V(110) Surfaces: A First-Principles Study
GAO Xiang1, ZHANG Guikai2, XIANG Xin2, LUO Lizhu1, WANG Xiaolin3()
1.Science and Technology on Surface Physics and Chemistry Laboratory, Jiangyou 621908, China
2.Institute of Materials, China Academy of Engineering Physics, Jiangyou 621907, China
3.China Academy of Engineering Physics, Mianyang 621900, China
Abstract

The oxygen adsorption behavior of V(110) surfaces and the alloying effects of Al, Ti, Cr are calculated using first-principles method. Then the surface phase diagrams for oxygen adsorption on binary V alloy surfaces are constructed combining with thermodynamics formalism. The microscopic mechanisms for oxidation of V alloy surfaces are analyzed. The calculated results of surface energies indicate that Al and Ti are preferable to be segregated on V(110) surfaces, while Cr is not. The oxygen adsorption behavior indicates that Al and Ti are favored to be oxidized on V(110) surfaces, while Cr is not. In this work, the microscopic oxidation mechanisms of V alloy surfaces have been successfully used to explain the experimental results of oxidation behavior. Moreover, the selective oxidation behavior of V-Al alloys has been predicted, and it would provide guidance for the fabrication of oxide tritium permeation barrier.

 ZTFLH: TG17
Fund: National Natural Science Foundation of China(11975213);National Research Project on the Development of Magnetically Confined Fusion Energy(2017YFE0300304);National Research Project on the Development of Magnetically Confined Fusion Energy(2018YFE0313100)
Corresponding Authors:  WANG Xiaolin     E-mail:  xlwang@caep.cn
 Fig.1  Schematic of possible adsorption sites on the V(110) surface (ot: on-top; sb: short-bridge; lb: long-bridge; 3f: 3-fold hollow)Color online Fig.2  Binding energies of oxygen on V(110) surface at different adsorption sites Fig.3  Charge density difference contours for O adsorbed on V(110) in 3f sites with the oxygen coverage Θ=0.25 ML (a) and Θ=1 ML (b) (The contour plane is along the [$121ˉ$] direction and perpendicular to the (110) surface. The red and blue regions represent the accumulation and depletion of charge density, respectively; unit: e/?3)Color online Fig.4  Partial densities of states (PDOSs) for O and surface-layer V atoms with Θ=0.25 ML (a) and Θ=1 ML (b) when O adsorbed in 3f sites (EF—Fermi level) Fig.5  The relative surface energies ($γRS$) vs the chemical potential $ΔμX$ (X=Al, Ti and Cr) of alloy elements for the clean V(110)-Al (a), V(110)-Ti (b) and V(110)-Cr (c) alloy surfaces Fig.6  Oxygen binding energies on the V(110)-Al (a), V(110)-Ti (b), V(110)-Cr (c) surfaces as functions of oxygen coverage Fig.7  Charge density difference contours for O adsorbed on V(110)-Al (a), V(110)-Ti (b) and V(110)-Cr (c) with Θ=0.25 ML(Each contour plane is along the [$121ˉ$] direction and perpendicular to the (110) surface. The red and blue regions represent the accumulation and depletion of charge density, respectively; unit: e/?3)Color online Fig.8  PDOSs for O adsorbed on V(110)-Al (a), V(110)-Ti (b) and V(110)-Cr (c) surfaces with Θ=0.25 ML Fig.9  The calculated relative surface energies of O/V(110)-Al (a, b), O/V(110)-Ti (c, d) and O/V(110)-Cr (e, f) systems under X rich (a, c, e) and V rich (b, d, f) conditions; and the calculated surface phase diagrams of the relative surface energies for O/V(110)-Al (g), O/V(110)-Ti (h) and O/V(110)-Cr (i) systems (ΔμO—chemical potential of oxygen, p—oxygen partial pressure, p0—standard atmospheric pressure)Color online