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The Crystal Structure of ζ 2 ‐Al 3 Cu 4‐δ
Author(s) -
Gulay L. D.,
Harbrecht Bernd
Publication year - 2003
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200390076
Subject(s) - superstructure , crystal structure , crystallography , metal , phase (matter) , diffraction , materials science , x ray crystallography , space group , copper , chemistry , metallurgy , physics , thermodynamics , optics , organic chemistry
The crystal structure of the ζ 2 ‐phase Al 3 Cu 4‐δ was determined by means of X‐ray powder diffraction: a = 409.72(1) pm, b = 703.13(2) pm, c = 997.93(3) pm, space group Imm2 , Pearson symbol oI24‐3.5 , R I = 0.0696. ζ 2 ‐Al 3 Cu 4‐δ forms a distinctive a × √3 a × 2 c superstructure of a metal deficient Ni 2 In‐type‐related structure. The phase is meta‐stable at ambient temperature. Between 400 °C and 450 °C it decomposes into ζ 1 ‐Al 3 Cu 4 and η 2 ‐AlCu. Entropic contributions to the stability of ζ 2 ‐Al 3 Cu 4‐δ are reflected in three statistically or partially occupied sites.