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MgAuGa and MgAu 2 Ga: first representatives of the Mg–Au–Ga system
Author(s) -
Smetana Volodymyr,
Corbett John D.,
Miller Gordon J.
Publication year - 2014
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s205322961400566x
Subject(s) - gallium , crystallography , group (periodic table) , magnesium , ternary operation , main group element , hexagonal crystal system , type (biology) , structure type , space (punctuation) , binary operation , space group , formula unit , chemistry , crystal structure , materials science , combinatorics , physics , mathematics , metallurgy , x ray crystallography , computer science , transition metal , geology , programming language , catalysis , organic chemistry , optics , operating system , paleontology , biochemistry , diffraction
MgAuGa (magnesium gold gallium), the first ternary representative of the Mg–Au–Ga system, crystallizes in the space group P 2 m and adopts the Fe 2 P structure type (Pearson symbol hP 9). Various phases with the general composition AB 2 have been reported in the surrounding binary systems, viz. Mg 2 Ga ( hP 18), MgGa 2 ( hP 6; CaIn 2 type), AuGa 2 ( cF 12; CaF 2 type), Au 2 Ga ( oS 24; Pd 2 As type) and Mg 2 Au ( oP 12; Co 2 Si type). In principle, MgAuGa can be obtained from each of them by partial replacement of the major element with the missing element. In fact, the structure of MgAuGa closely resembles hexagonal Mg 2 Ga through a direct group–subgroup relationship. MgAu 2 Ga (magnesium digold gallium) also crystallizes hexagonally in the space group P 6 3 / mmc and is isotypic with Na 3 As. It adopts the structure of another binary compound, viz. Mg 3 Au ( hP 8), but shows an unexpected distribution of Mg, Au, and Ga among the atomic positions of the asymmetric unit. Both MgAuGa and MgAu 2 Ga can be described as formally anionic Au/Ga frameworks, with pseudo‐hexagonal tunnels around Mg in MgAuGa or cages in MgAu 2 Ga.