Pd2Cd11− (0.21≤δ≤0.51)–a partly disordered γ-brass type phase and Pd0.238Cd0.762-a γ-brass related incommensurate phase in the palladium–cadmium system

Structure and stability of γ1-AuZn2.1: a γ-brass-related complex phase in the Au-Zn System

γ₁-AuZn_2.1 in the Au-Zn binary system has been synthesized and its structure analyzed by single-crystal X-ray diffraction. It crystallizes in the trigonal space group P31m (No. 157) with ∼227 atoms per unit cell and represents a \surd3a × \surd3a × c superstructure of rhombohedrally distorted γ-Au_5-xZn_8+y. The structure is largely tetrahedrally closed packed. The formation of γ₁-AuZn_2.1 can be understood within the framework of a Hume-Rothery stabilization mechanism with a valence electron concentration of 1.68 e/a (valence electrons per atom).

Crystal structures of two very similar 2 × 2 × 2 superstructures of γ-brass-related phases in ternary Ir-Cd-Cu system

A binary phase Ir₈Cd₄₁ 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 Ir₈Cd₄₁ 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 Ir₈Cd₄₁ adopts V₈Ga₄₁-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 Rh₇Mg₄₄ structure type.

Au10Mo4Zn89: a fully ordered complex intermetallic compound analyzed by TOPOS

The compound Au10Mo4Zn89 has been synthesized, and its structure has been analyzed by single-crystal X-ray diffraction. The compound crystallizes in cubic space group F43m (No. 216) with a unit cell that contains 412 atoms. The structure is largely tetrahedrally closely packed, but an octahedral arrangement of atoms is incompatible with tetrahedral close packing. The structure of the ordered Au10Mo4Zn89 compound has been described by using the algorithm of automatic geometric and topological analysis that is implemented in TOPOS as the "Nanoclustering" procedure.