Studies on the oxidation behaviour of intermetallic compounds

Article abstract of DOI:10.1007/BF00551917

In recent years hydrogen-absorbing intermetallic compounds have received much attention for their role in catalyzing CO hydrogenation and other reactions. In view of the vast interest shown in the oxidized/decomposed intermetallics as catalysts (both preoxidized and those oxidized during reaction), it appears to be very important to know the oxidation behavior of the intermetallic compounds, especially the kinetics of the oxidation process and the various species formed due to oxidation at various temperatures. The oxidation behavior of the AB₅ type intermetallic compounds CaNi₅ and LaNi₅ has been studied at different temperatures ranging from 100 to 800°C. The kinetic results indicate that the element A (Ca, La) is first oxidized rapidly followed by slower oxidation of nickel. X-ray diffractograms of the oxidized LaNi₅ show the formation of ternary phases like LaNiO₃ and La₂ NiO₄ at temperature as low as 400°C. A comparison between the oxidation behavior of the two compounds reveals that CaNi₅ is more resistant to oxidation and decomposition than the LaNi₅ system.