Dislocations in neodymium gallium garnet (Nd₃Ga₅O₁₂ or NdGG)

Abstract

Dislocations in imperfect (1 1 1) and (1 0 0) wafers of neodymium gallium garnet (Nd₃ Ga₅ O₁₂ or NdGG) have been examined using etch pits and the bi-refringence method. Long straight dislocations, large prismatic loops, small prismatic loops, dislocation nodes, and low-angle grain boundaries were observed. The Burgers vectors of some of the dislocations lay along the 〈1 1 0〉 or 〈1 1 1〉 directions. Dislocations with Burgers vectors along 〈1 0 0〉 may have been present, but conclusive evidence for this was not obtained. The diameter of the smallest prismatic loop was 3.1μm. It is thought to be the smallest dislocation loop observed by the bi-refringence method. The rotation across the low-angle grain boundaries was ∼10⁻⁶°.