Application of the five-dimensional maximum-entropy method to the structure refinement of decagonal Al₇₀Mn₁₇Pd₁₃

Abstract

The structure of decagonal Al₇₀Mn₁₇Pd₁₃ was refined on the basis of a single-crystal X-ray data set, whereby information obtained from the five-dimensional maximum-entropy method was used to modify the structure model, that is the position, shape and chemical composition of the occupation domains in the internal space. The structure model is based on high-resolution transmission electron microscopy images and considerations in five-dimensional space. The refinement with 121 parameters gives for 1428 reflections R _w = 15·74% (R = 23·41%) or R _w = 12·9% (R = 12·9%) for the strongest 500 reflections. The results are compared with the results of a refinement of decagonal Al_70·5Mn_16·5Pd₁₃ by Steurer et al. in 1993. Special effort was made to elucidate the importance of refining atom shifts from their ideal positions as well as the necessity of using subdividable occupation domains.