Abstract
Structures of {111} and {310} plate-zones explaining the rod distributions of intensity weight in reciprocal space revealed in X-ray patterns from solid solutions of NaCl containing a few per cent of CaCl2 (reported in Part I) is proposed. The plate-zones are considered to be composed of a number of smaller units, called platelets, which are disposed in anti-phase relation among themselves in a plate-zone. We proposed probable models of the structures of the two kinds of platelets making up the {111} plate-zone and the {310} plate-zone respectively by assuming that each platelet has crystal structure resembling that of CaCl2, retaining, however, coherency with the matrix. The qualitative agreement was found between observed and calculated intensities of rod distributions in reciprocal space.
The proposed CaCl2-like structure of the {111} platelet seems to be plausible one, since it was found that its orientation was followed by that of CaCl2 particle which precipitated by a certain heat treatment. In the case of the ⟨310⟩ rods, the proposed structure of the {310} plate-zones is rather tentative. Absolute intensity of the ⟨111⟩ rods was roughly estimated by comparing it with that of thermal diffuse scattering from pure NaCl crystal. It was found that we could expect the intensity of the diffuse spots due to the rods to be of the same order as that of thermal diffuse scattering even when only a few per cent of the dissolved Ca++ ions are participating in the {111} plate-zones.
