Studying the Interaction of LaNi5 Intermetallic Alloy with Oxygen by SIMS

• Published in: Surface investigation, x-ray, synchrotron and neutron techniques x-ray, synchrotron and neutron techniques, 2020-11, Vol.14 (6), p.1358-1365
• Main Authors: Litvinov, V. A., Okseniuk, I. I., Shevchenko, D. I., Bobkov, V. V.
• Format: Article
• Language: English
• Subjects: Chemistry and Materials Science; Materials Science; Surfaces and Interfaces; Thin Films
• ISSN: 1027-4510; 1819-7094
• DOI: 10.1134/S102745102006035X

— This article presents the chemical composition of surface monolayers of LaNi 5 intermetallic alloy during interaction with oxygen determined by secondary-ion mass spectrometry. It is demonstrated that at higher partial pressures of oxygen the measured mass spectra contain a large set of emissions, and positive and negative secondary ions containing both components of the alloy and oxygen. This evidences that oxygen, incident on the surface, forms firm bonds with lanthanum and nickel. Existence of lanthanum-nickel cluster secondary ions containing oxygen in the spectra makes it possible to believe that as a consequence of oxygen impact a complex chemical structure is formed on the surface and near the surface. The structure contains oxygen and both lanthanum and nickel. With an increase in the partial pressure of oxygen the ratio of the number of oxygen atoms to the number of metal atoms in such lanthanum-nickel-oxide structure increases. Judging by the diversity of the composition of the observed secondary ions, such an oxide structure is not homogeneous but is a superposition of oxide structures with various stoichiometric ratios.