Dislocations in orthorhombic ammonium perchlorate

Abstract

Cleavage and growth faces of ammonium perchlorate have been examined by high-power interference–contrast microscopy. From the observed directions of etch-pit arrays on three crystallographically distinct faces of the orthorhombic form of ammonium perchlorate, and also from the nature of the slip bands on deliberately deformed crystals, the nature of the dislocations present has been clarified. All the observed alignments and bands on the various faces may be accounted for in terms of dislocation movement on (20), (201), (401), (40), (110), (10), (010), and (001) planes, the direction of the Burgers vector being known for all but one of the active slip planes. Preferential evaporation occurs from dislocation cores emergent at (001) faces.