Plasma Oscillation of Electrons in Alloy I. Ag-Al Alloy

Abstract

The characteristic electron energy loss spectra of Ag-Al alloy are studied at various compositions using the Möllenstedt-type analyzer with the primary electron energy of 30 KeV. The energy loss due to the plasma oscillation decreases continuously from 3.5 eV to 3.3 eV with increase of concentration of Al and varies to 14.8 eV at 70 atomic per cent Al discontinuously. The intermediate energy value of plasma excitation between 3.5 and 14.8 eV is not observed. The 14.8 eV energy loss shows always a clear dispersion, i. e. the change in energy value with scattering angle, as is the case for pure Al. The other energy loss values vary discontinuously at 20 and 70 atomic per cent of Al. The discontinuous change of plasma energy can be explained by taking account of the interaction between plasma oscillation and inter-band transition. The energy spectra of ζ-phase (h.c.p. type) and µ-phase (β-Mn type) alloys are also observed. These spectra are quite different from the above spectra, and plasma energies of ζ-phase and µ-phase are considered to be 5.2 eV and 4.5 eV, respectively.