Effects of bulk impurity concentration on the reactivity of metal surface: sticking of hydrogen molecules and atoms to polycrystalline Nb containing oxygen.
Effects of bulk impurity concentration on the reactivity of metal surface: sticking of hydrogen molecules and atoms to polycrystalline Nb containing oxygen.
复制标题
体相杂质浓度对金属表面反应性的影响：氢分子和原子对含氧多晶铌的粘附。
DOI：
10.1063/1.2804874
复制
发表时间：
2007
影响因子：
4.4
通讯作者：
K. Hashizume
中科院分区：
文献类型：
--
作者：
Y. Hatano;Kuniaki Watanabe;A. Livshits;A. Busnyuk;V. Alimov;Y. Nakamura;K. Hashizume
金属表面的非金属杂质会大大降低金属的化学反应活性。本文以氢分子和氢原子粘附在含溶质氧的Nb [多晶，主要是（100）]上为例，在较宽的温度范围内研究了体相杂质对金属表面反应性的影响。在所有研究的表面温度下，T（S）（300-1400 K）时，我们发现体相氧浓度C（O）对H（2）分子解离粘附的积分概率α（H（2））有很强的影响，随后氢溶解在金属晶格中：α（H（2））随C（O）从0.03增加到1.5at. %.发现粘附系数α（H（2））依赖于T（S）而不依赖于气体温度。C（O）对α（H（2））的影响是由无氧位点（覆盖层中的空穴）的存在作为Nb上氧单层中表面反应的活性中心来解释的。与H（2）分子相反，发现H原子以与1相当的概率粘附并溶解在氧覆盖的Nb中，既不依赖于C（O）也不依赖于T（S）。这证明，与H（2）分子不同，H原子主要通过被氧覆盖的规则表面位置而不是通过覆盖层中的孔溶解。
Nonmetallic impurities segregated onto metal surfaces are able to drastically decrease the chemical reactivity of metals. In the present paper, effects of bulk impurities on the reactivity of metallic surfaces were investigated in a wide temperature range on an example of the sticking of hydrogen molecules and atoms to Nb [polycrystalline, with mainly (100)] containing solute oxygen. At all the investigated surface temperatures, T(S) (300-1400 K), we found the bulk oxygen concentration C(O) to have a strong effect on the integral probability, alpha(H(2) ), of dissociative sticking of H(2) molecules followed by hydrogen solution in the metal lattice: alpha(H(2) ) monotonically decreased by orders of magnitude with increasing C(O) from 0.03 to 1.5 at. %. The sticking coefficient alpha(H(2) ) was found to depend on T(S) but not on the gas temperature. The effect of C(O) on alpha(H(2) ) is explained by the presence of oxygen-free sites (holes in coverage) serving as active centers of the surface reaction in the oxygen monolayer upon Nb. In contrast to H(2) molecules, H atoms were found to stick to, and be dissolved in, oxygen-covered Nb with a probability comparable to 1, depending neither on C(O) nor on T(S). This proves that, unlike H(2) molecules, H atoms do stick to be dissolved mainly through regular surface sites covered by oxygen and not through the holes in coverage.