The surface energy of quasi-amorphous γ alumina calculated from the temperature of the γ→α transition

The excess surface energy of one phase with respect to another is computable at the transition temperature from thermodynamic tables. Below the transition temperature, the stability of the phase with the highest bulk free energy is measured by the excess surface energy. Among several known examples, the stability of high surface area γ alumina is especially effective in catalysis because the theoretically more stable α phase is less active, being poorer in coordinately unsaturated sites. A simple method for calculating the surface energy of γ alumina with reference to the theoretical surface energy of α alumina is suggested.