INDEXING OF DIFFRACTION PATTERNS AND INDENTIFICATION OF FAULT VECTOR IN DECAGONAL AL65CU20CO15 PHASE

Characterisations of defect structures such as pencil disorder, faulti ng in quasiperiodic layers and dislocation in decagonal quasicrystals has assumed importance currently. The first step towards a complete un derstanding of these defects requires easy and unambiguous method of i ndexing the diffraction patterns. The present study is devoted to this task. New rules have been framed for an unambiguous indexing of the d iffraction patterns following the model of Mandal and Lele. The scheme is applied to the indexing of important electron diffraction patterns from a decagonal Al-65 Cu-20 Co-15 alloy and the indices for the dire ction of streaking ill some of the diffraction patterns have been foun d and are of the type [001 (1) over bar 00].