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Synthesis and crystal structure of a new Cu 3 Au‐type ternary phase in the Au–In–Pd system: distribution of atoms over crystallographic positions
Author(s) -
Ptashkina Evgeniya A.,
Kabanova Elizaveta G.,
Tursina Anna I.,
Yatsenko Alexandr V.,
Kuznetsov Victor N.
Publication year - 2018
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/s2053229618001973
Subject(s) - crystallography , ternary operation , diffraction , homogeneity (statistics) , crystal structure , materials science , scattering , chemistry , physics , optics , statistics , mathematics , computer science , programming language
A new Cu 3 Au‐type ternary phase (τ phase) is found in the AuPd‐rich part of the Au–In–Pd system. It has a broad homogeneity range based on extensive (Pd,Au) and (In,Au) replacement, with the composition varying between Au 17.7 In 25.3 Pd 57.0 and Au 50.8 In 16.2 Pd 33.0 . The occupancies of the crystallographic positions were studied by single‐crystal X‐ray diffraction for three samples of different composition. The sites with m m symmetry are occupied by atoms with a smaller scattering power than the atoms located on 4/ mmm sites. Two extreme structure models were refined. Within the first, the occupation type changes from (Au,In,Pd) 3 (Pd,In) to (Au,Pd) 3 (In,Pd,Au) with an increase in the Au gross content. For the second model, the occupation type (Au,In,Pd) 3 (Pd,Au) remains essentially unchanged for all Au concentrations. Although the diffraction data do not allow the choice of one of these models, the latter model, where Au substitutes In on 4/ mmm sites, seems to be preferable, since it agrees with the fact that the homogeneity range of the τ phase is inclined to the Au corner and provides the same occupation type for all the studied samples of different compositions.