The anomalous boundary effect similar to these found by Fukushima in guartz were studied by x-ray diffraction topography methods in Ge and Si single crystals. Both Laue and Bragg cases are examined using CuKα and AgKα radiations for various net planes. Results are reasonably explained by assuming a strain gradient perpendicular to the boundary as the previous workers. It was shown that the Borrmann effect as well as the ordinary extinction effect are useful in point-by-point examination of lattice distortions in nearly perfect single crystals.
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