Unusual crystallographic ordering of two neighbouring elements - Cd and In in Cd2Cu3In, the first example in ternary Laves phase

Abstract

A ternary intermetallic compound Cd2Cu3In that is an ordered substitution variant of cubic MgCu2 structure type has been uncovered. The Laves phase is synthesized by high-temperature solid-state method and it is isostructural with Al2Mo3C. It crystallizes in cubic chiral space group P4132 (213) with the lattice parameter a = 7.3254(2) Å. A perceptible phase width is found around Cd2Cu3In for the series allowing a successive substitution of constituent elements. The unit cell of Cd2Cu3In contains 24 atoms, which are distributed over 3 independent crystallographic sites. The structure is described as a three-dimensional network of vertex sharing tetrahedra, made of relatively more electronegative Cu and In atoms, whereas slightly more electropositive Cd atoms form a diamond-like network. An unusual atomic ordering of two neighbouring elements Cd and In is confirmed by first principle DFT calculations. Cd2Cu3In is the first representative among the ternary Laves phases where two neighbouring elements (Cd and In) ordered in its crystal structure. The density of states (DOS) and crystal orbital Hamiltonian population (COHP) are calculated to explain the stability and bonding characteristics in the structure of Cd2Cu3In.

Department(s)

Chemistry and Biochemistry

Document Type

Article

DOI

https://doi.org/10.1016/j.jallcom.2020.156054

Keywords

Atomic ordering, First principle total energy calculations, Intermetallics, Laves phase, Phase width, X-ray diffraction

Publication Date

12-5-2020

Journal Title

Journal of Alloys and Compounds

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