Dynamic electron scattering distinguishes dodecahedral and tetrahedral crystallographic sites in garnet structure

It is shown in this letter that, in contrast to the accepted belief in the literature, it is possible to determine if a minority component is located on the dodecahedral, octahedral, or tetrahedral sites in a garnet single cr ystal. This prediction of ours is based on dynamical Bloch-wave calculation s and proved experimentally with x-ray measurements in a transmission elect ron microscope. The previous literature seemed to agree on the assumption t hat the dodecahedral and tetrahedral sites are indistinguishable from each other. (C) 1999 American Institute of Physics. [S0003-6951(99)04125-X].