Peculiarities in the plasma resonance of binary amorphous Al–TM alloys Original Research Article

Simple amorphous phases have shown to be ideal model systems for exploring the mechanisms of structure formation in a Hume-Rothery manner. In these systems the electron density is the key quantity. We briefly review measurements for simple amorphous alloys (s- and p-electrons at the Fermi energy only), especially for amorphous semiconductors. The results coincide excellently with theory, using the usual valencies of the elements. In contrary, adding elements with d-electrons as in binary amorphous Al–TM alloys (TM: Ca, Ti, V, Cr, Mn, Fe, Co, Ni) causes a breakdown of this simple approach. All the 3d-TM seem to exhibit an identical effective valency. In both cases, the electron densities obtained are compared to those, necessary for explaining structural data.