X-ray diffraction topography observations of the core in Bi12SiO20 crystals doped with Mn

The core region in a bismuth silicate—Bi12SiO20 (BSO) crystal doped with Mn was examined by X-ray double-crystal diffraction topography. Specific features were observed in the topographies as lines and contrast differences that point to defects occupying the central part of the crystal. We discuss the nature of these defects and propose an explanation in terms of stacking faults arranged in different structures.