X-ray diffraction study of a Bi4Ge3O12 crystal

A Czochralski grown Bi4Ge3O12 crystal plate of (BGO) was examined by several X-ray diffraction methods. The crystal structure, lattice parameter and the atomic positions were determined by single crystal X-ray diffractometry. The X-ray diffraction double crystal traverse topography (XRDT) images reveal that the core area of the crystal is strained and occupied by dislocations with different Burgers vectors (but mainly b = 〈0 0 1〉), lines lying along the growth axis [0 1 1] and density that does not exceed 20–30 cm−2. It was established that the almost entire crystal surface (without the core area) is occupied by two-dimensional defects, probably some form of stacking faults. Several Lauegrams were taken from different parts of the plate that showed no presence of any two-dimensional defects. The X-ray microprobe analysis of all three-dimensional defects on the crystal surface showed that all they were probably gas bubbles and a GeO2-precipitate was detected in one case only.