An X-ray multiple diffraction study of yttrium iron garnet crystals

Investigations by X-ray multiple diffraction have revealed a departure from cubic symmetry in the growth surfaces of yttrium iron garnet single crystals grown in a PbO-PbF₂, B₂O₃ flux. The observed structural modification is attributed to an extensional deformation of the lattice in the direction of crystal growth i.e. <110> or <112>. It has been demonstrated that a growth surface exhibiting a structural deformation reverts to cubic symmetry on light abrasion. The lattice parameters of the crystals were determined, after elimination of any structural modification, from the angular separation of doubly diffracted beams. Measured values of the lattice parameters of the crystals studied covered the range 12.3752 to 12.3800 Å. No correlation was established between impurity concentrations in the crystals, for example lead and the rare earths, and the lattice parameter or the occurrence of a structural modification.