The interaction of oxygen with single crystal surfaces was investigated over the temperature range used for thermo-emission. The relative surface concentrations of La, B and O were measured by high temperature AES and plotted as isothermal lines. A prominent change of surface composition was found in passing from the clean to the oxidized surface state. Mass desorption experiments indicated that the oxygen left the surface as oxides of the matrix elements. A strong decomposition took place, forming preferentially (100) planes; as seen in SEM micrographs.

The Interaction of Oxygen with LaB6 Single Crystal Surfaces at Elevated Temperatures. Klauser, S.J., Bas, E.B.: Applications of Surface Science, 1979, 3[3], 356-63