The structure of calcium-aluminium glasses: X-ray diffraction and computer simulation studies

Abstract

The authors present an investigation of the atomic structure of the metallic glass Ca₆₀Al₄₀ by energy-dispersive X-ray diffraction and computer simulation studies based on pseudopotential-derived interatomic forces. The characteristic features of the structure of Ca₆₀Al₄₀ are the large contraction of the Ca-Ca nearest-neighbour distances compared with pure Ca metal and a rather broad and asymmetric nearest-neighbour peak in the pair correlation function. The theoretical model explains the contraction of the Ca-Ca distances but not the large asymmetry of the peaks. They tentatively attribute the asymmetry to a modification of the dielectric screening function arising from the short electronic mean free path in this high-resistivity alloy. The theoretical model also points to a well defined topological short-range order and a negligible chemical short-range order.