Affiliation:
1. Institut für Anorganische und Analytische Chemie , Universität Münster , Corrensstrasse 30 , 48149 Münster , Germany
Abstract
Abstract
The crystal structures of the U3Si2-related intermetallic compounds RE
2Pd2Cd (RE = Nd, Sm, Gd, Dy) and RE
2Ga2Mg (RE = Tb, Er, Tm, Lu) were studied from single crystal X-ray diffraction data at T = 90 K in order to understand the slightly enhanced U
33 displacements of the 2a positions in their room temperature structures. The compounds Sm2Pd2Cd, Gd2Pd2Cd and Dy2Pd2Cd show a decrease of the ratio of U
33 to U
11 for the cadmium atoms, leading to a more isotropic behavior at low temperature, keeping the P4/mbm space group symmetry. Nd2Pd2Cd shows a translationengleiche symmetry reduction to space group P4bm along with a weak puckering effect with shorter (342.7 pm) and longer (345.7 pm) Cd–Nd distances within the Cd@Nd8 square prisms. This new, non-centrosymmetric superstructure variant was also observed for the magnesium compounds Tb2Ga2.069Mg0.931, Er2Ga2.104Mg0.896, Tm2Ga2.097Mg0.903 and Lu2Ga2.173Mg0.827, which show small degrees of Mg/Ga mixing.
Reference36 articles.
1. Zachariasen, W. H. Acta Crystallogr. 1949, 2, 94–99; https://doi.org/10.1107/s0365110x49000217.
2. Remschnig, K.; Le Bihan, T.; Noël, H.; Rogl, P. J. Solid State Chem. 1992, 97, 391–399; https://doi.org/10.1016/0022-4596(92)90048-z.
3. Villars, P.; Cenzual, K. Pearson’s Crystal Data: Crystal Structure Database for Inorganic Compounds (Release 2022/23); ASM International®: Materials Park, Ohio (USA), 2022.
4. Rieger, W.; Nowotny, H.; Benesovsky, F. Monatsh. Chem. 1964, 95, 1502–1503; https://doi.org/10.1007/bf00901704.
5. Lukachuk, M.; Pöttgen, R. Z. Kristallogr. 2003, 218, 767–787; https://doi.org/10.1524/zkri.218.12.767.20545.