Plasma Oscillation of Electrons in Alloy III. Al-Be, Al-Ge, and Al-Sn Eutectoids

The plasma oscillation of electrons in Al-Be, Al-Ge and Al-Sn eutectoids has been studied using the method of energy analysis of electrons passed through a thin foil of eutectoid. The energy of the plasma oscillation of electrons in eutectoid depends upon the grain sizes of component elements. In the case of Al-Be, two kinds of the plasma oscillation of Al and Be themselves are excited, if the grain sizes of Al and Be are more than several hundreds angstroms. On the other hand, if the grain sizes are less than about 60Å, only one plasma oscillation due to the bulk plasma oscillation is excited. For an intermediate grain size, two plasma oscillations with energy values each of which shift from that of Al or Be are observed. The grain size dependency of the plasma oscillation in eutectoid is explained phenomenologically. The energy loss value, the dispersion relation, the cutoff scattering angle, θ c (corresponding to the cutoff wave number, k c ), the angular dependences of the intensity and the half breadth of energy loss peak of the plasma oscillation in small grain size eutectoid less than about 60Å were measured. Those values are compared with the corresponding theoretical values.