Temperature-programmed desorption was used to study oxidation of the (100) surface by O2. It was found that the surface oxide was removed by the desorption of BO and LaO between 1300 and 1500K and the desorption of B2O2 between 1100 and 1500K. The desorption of each of the three oxides exhibited a distinctly different dependence upon O2 exposure. For all but the lowest coverages, LaO desorption obeyed zero-order desorption kinetics, with an activation energy of 775kJ/mol. At the highest oxide coverages, B2O2 obeyed first-order kinetics with a constant desorption peak temperature of 1170K. The first-order rate constant corresponding to this B2O2 peak was 1.3 x 109exp[-233(kJ/mol)/RT]/s. Similarly, a first-order desorption peak for BO at 1485-1500K had a first-order rate constant of 6.3 x 109exp[-303(kJ/mol)/RT]/s. The results were explained in terms of various surface reactions involving B2O3 and La2O3.

Oxide Thermal Desorption from the LaB6(100) Surface Following Reaction with O2. Ozcomert, J.S., Trenary, M.: Chemistry of Materials, 1993, 5[12], 1762-71