Study on the Intensity Anomaly of Electron Diffraction Powder Patterns from Minute Silver Crystallites

Abstract

Electron diffraction powder patterns from extremely minute crystallites of evaporated silver show a peculiar intensity anomaly: the most remarkable part of it is that the ratio of the integral intensity of the (200)-reflection to that of the (111)-reflection is far smaller than the one calculated, and the former reflection is much broader than the latter. The anomaly can be ascribed to a stacking disorder in the (111)-plane in the minute silver crystallites. The calculated line profiles can be made to coincide with the observed ones, if the following parameters are adequately determined: α, the probability with which the stacking fault occurs; L₁ and L₂, the dimensions of the crystallites parallel and perpendicular respectively to the (111)-plane of the crystallite; and \sqrt⟨u²⟩_AV., the amount of the average lattice distortion due to small inhomogeneous lattice distortions in the crystallites. For example they turned out to be, for one specimen, α=0.84, L₁=20 Å, L₂=47 Å; for turned specimen, α=0.70, L₁=14 Å, L₂=33 Å and \sqrt⟨u²⟩_AV=0.14 Å.