TY - JOUR
T1 - Structure analysis of complex metallic alloys in the Eu-Ag-In system by X-ray diffraction
AU - Gómez, Cesar Pay
AU - Morita, Yoshiki
AU - Yamamoto, Akiji
AU - Tsai, An Pang
PY - 2009
Y1 - 2009
N2 - In this work we investigate the complex atomic structures of two CMAs in the Eu-Ag-In system, these are quasicrystal approximants and their structures are similar to those of the 1/1 and 2/1 approximants found in the Yb-Cd system. The similarities between the Yb-Cd and Eu-Ag-In systems indicate that the RE-Ag-In systems in several ways can be treated as pseudo-binary. The investigated phases however also show some interesting differences; when Cd is replaced by the elements Ag and In partial chemical disorder is introduced into the system. As a response, the positional disorder which is usually observed in certain atomic positions for these types of approximants tends to disappear. The complete structures refined from single crystal data are described in detail and the differences with other related phases are highlighted. The 2/1 approximant in the Eu-Ag-In system is the first to exhibit such a degree of structural perfection in terms of positional order, a feature which makes this phase very suitable for further studies of chemical order and also can give insight into the local structures of related disordered phases. Electron diffraction studies on the 1/1 approximant phase have previously shown the presence of weak superlattice reflections, indicating a superstructure similar to that of the related phase Eu4Cd25. However, no superlattice reflections could be observed by single crystal diffraction and it is thus concluded that the phase has a disordered average structure with possible short to medium range superlattice ordering.
AB - In this work we investigate the complex atomic structures of two CMAs in the Eu-Ag-In system, these are quasicrystal approximants and their structures are similar to those of the 1/1 and 2/1 approximants found in the Yb-Cd system. The similarities between the Yb-Cd and Eu-Ag-In systems indicate that the RE-Ag-In systems in several ways can be treated as pseudo-binary. The investigated phases however also show some interesting differences; when Cd is replaced by the elements Ag and In partial chemical disorder is introduced into the system. As a response, the positional disorder which is usually observed in certain atomic positions for these types of approximants tends to disappear. The complete structures refined from single crystal data are described in detail and the differences with other related phases are highlighted. The 2/1 approximant in the Eu-Ag-In system is the first to exhibit such a degree of structural perfection in terms of positional order, a feature which makes this phase very suitable for further studies of chemical order and also can give insight into the local structures of related disordered phases. Electron diffraction studies on the 1/1 approximant phase have previously shown the presence of weak superlattice reflections, indicating a superstructure similar to that of the related phase Eu4Cd25. However, no superlattice reflections could be observed by single crystal diffraction and it is thus concluded that the phase has a disordered average structure with possible short to medium range superlattice ordering.
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U2 - 10.1088/1742-6596/165/1/012045
DO - 10.1088/1742-6596/165/1/012045
M3 - Article
AN - SCOPUS:67651007353
VL - 165
JO - Journal of Physics: Conference Series
JF - Journal of Physics: Conference Series
SN - 1742-6588
M1 - 012045
ER -