Theoretical study of the properties of X-ray diffraction moire fringes. II. Illustration of angularly integrated moire images

Using a theory of X-ray diffraction moire fringes developed in a previous paper, labelled Part I [Yoshimura (2015). Acta Cryst. A71, 368-381], the X-ray moire images of a silicon bicrystal having a weak curvature strain and an interspacing gap, assumed to be integrated for an incident-wave angular width, are simulation-computed over a wide range of crystal thicknesses and incident-wave angular width, likely under practical experimental conditions. Along with the simulated moire images, the graphs of characteristic quantities on the moire images are presented for a full understanding of them. The treated moire images are all of rotation moire. Mo K alpha(1) radiation and the 220 reflection were assumed in the simulation. The results of this simulation show that fringe patterns, which are significantly modified from simple straight fringes of rotation moire, appear in some ranges of crystal thicknesses and incident-wave angular width, due to a combined effect of Pendellosung oscillation and an added phase difference from the interspacing gap, under the presence of a curvature strain. The moire fringes which slope to the perpendicular direction to the diffraction vector in spite of the assumed condition of rotation moire, and fringe patterns where low-contrast bands are produced with a sharp bend of fringes arising along the bands are examples of the modified fringe pattern. This simulation study provides a wide theoretical survey of the type of bicrystal moire image produced under a particular condition.