In-framework ion dipole polarizabilities in non-porous and porous silicates and aluminosilicates, determined from Auger electron spectroscopy data

The in-framework ion dipole polarizability is determined by evaluating the absolute extra-atomic relaxation energy during the two-electron Auger process. A simple model has been derived by combining general relaxation theory with an electrostatic model due to Moretti (Surf. Interface Anal., 1990, 16, 159). The method is applied to crystalline MgO in order to check its validity. The result is in very good agreement with (ab initio) theoretical and experimental data. When applied to porous and non-porous silicates and aluminosilicates, the method is able to distinguish between different types of in-framework oxygens according to their site symmetry and the nature of the cation (Si, Al).