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Crystal structures of two very similar 2 × 2 × 2 superstructures of γ‐brass‐related phases in ternary Ir–Cd–Cu system
Author(s) -
Ghanta Sivaprasad,
Roy Nilanjan,
Jana Partha Pratim
Publication year - 2020
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520619015488
Subject(s) - isostructural , crystallography , superstructure , ternary operation , crystal structure , materials science , phase (matter) , brass , ternary numeral system , cluster (spacecraft) , copper , chemistry , metallurgy , thermodynamics , physics , organic chemistry , computer science , programming language
A binary phase Ir 8 Cd 41 in the Ir–Cd binary system and novel ternary phases in the Ir–Cd–Cu system have been synthesized from the constituent elements using high‐temperature solid‐state synthesis. The structure of previously reported Ir 8 Cd 41 and newly found ternary phases in the Ir–Cd–Cu system have been characterized by single crystal X‐ray diffraction and EDS analysis. The structural analysis reveals that Ir 8 Cd 41 adopts V 8 Ga 41 ‐type structure and ternary Ir–Cd–Cu phases adopt two 2 × 2 × 2‐superstructures of the γ‐brass‐related phase. The structures of ternary Ir–Cd–Cu phases are associated with structural disorder (vacancies as well as mixed site occupancies). The crystal structures of the ternary phases are viewed using layer description and cluster concept. The 2 × 2 × 2‐superstructure of γ‐brass‐related phases in the Cu‐poor region are not isostructural with the phases in the Cu‐rich region, and they are consistent with the absence of a continuous phase region between two 2 × 2 × 2‐superstructures of γ‐brass‐related phases. In the Cu‐poor region, the structures contain ∼404 atoms per unit cell, whereas in the Cu‐rich phases the structures contain ∼411 atoms in their respective unit cells. The crystal structures in the Cu‐poor region represent a new type in the 2 × 2 × 2‐superstructure of γ‐brass‐related phases in view of the combination of constituent cluster types, whereas the structures in the Cu‐rich region adopt the Rh 7 Mg 44 structure type.