Bethe-lattice approach for electronegativity calculation in amorphous alloys and its correlation with the chemical shift: alpha-SiOx and alpha-SiNx cases

We have developed a new method for evaluating the electronegativities of solid alloys. They are described by a Bethe-lattice and for each single atom of the alloy Sanderson's electronegativity value has been adopted. The calculation proceeds in the spirit of the original model proposed by Lucovsky. However the present method makes use of an infinite lattice and in contrast with Lucovsky's one, perfectly satisfies the electronegativity equalization principle. We tested the model by evaluating the chemical shift of the Si 2p core level binding energies in silicon oxide and silicon nitride as a function of alloy composition obtaining a very good agreement with the experimental data. A comparison with the Lucovsky model shows that the present one is superior in predicting the chemical shifts and, therefore, can be regarded as a refinement of that model.