Indexing of diffraction patterns and indentification of fault vector in decagonal Al65Cu20Co15 phase

Characterisations of defect structures such as pencil disorder, faulting in quasiperiodic layers and dislocation in decagonal quasicrystals has assumed importance currently. The first step towards a complete understanding of these defects requires easy and unambiguous method of indexing the diffraction patterns. The present study is devoted to this task. New rules have been framed for an unambiguous indexing of the diffraction patterns following the model of Mandal and Lele. The scheme is applied to the indexing of important electron diffraction patterns from a decagonal Al₆₅ Cu₂₀ Co₁₅ alloy and the indices for the direction of streaking in some of the diffraction patterns have been found and are of the type .