The conductivity of oxide cathodes. Part 11: Thermal stability of the alkaline-earth oxides

The three common alkaline-earth oxides are examined for thermal stability at 1200°C. In an experimental arrangement involving a massive evaporation from a platinum substrate it is shown that barium oxide is removed in the form of unchanged molecules while strontium and calcium oxides leave the substrate in elemental form as metal and oxygen. It is concluded that the dissociation is a thermal one and not concerned with the nature of the substrate.