Isolation of the new cubic phases RE4FeGa12-xGex (RE = Sm, Tb; x = 2.5) from Molten gallium: Single-crystal neutron diffraction study of the Ga/Ge distribution

Marina A. Zhuravleva, Xiaoping Wang, Arthur J. Schultz, Thomas Bakas, Mercouri G. Kanatzidis

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Abstract

The compounds RE4FeGa12-xGex (RE = Sm, Tb) were discovered in reactions employing molten Ga as a solvent at 850 °C. However, the isostructural Y4FeGa12-xGex was prepared from a direct combination reaction. The crystal structure is cubic with space group Im3m, Z = 2, and a = 8.657(4) Å and 8.5620(9) Å for the Sm and Tb analogues, respectively. Structure refinement based on full-matrix least squares on F02 resulted in R1 = 1.47% and wR2 = 4.13% [1 > 2σ(1)] for RE = Sm and R1 = 2.29% and wR2 = 7.12% [1 > 2σ(1)] for RE = Tb. The compounds crystallize in the U4Re7Si6 structure type, where the RE atoms are located on 8c (1/4, 1/4, 1/4) sites and the Fe atoms on 2a (0, 0, 0) sites. The distribution of Ga and Ge in the structure, investigated with single-crystal neutron diffraction on the Tb analogue, revealed that these atoms are disordered over the 12d (1/4, 0, 1/2) and 12e (x, 0, 0) sites. The amount of Ga/Ge occupying the 12d and 12e sites refined to 89(4)/11 and 70(4)/30%, respectively. Transport property measurements indicate that these compounds are metallic conductors. Magnetic susceptibility measurements and Mössbauer spectroscopy performed on the Tb analogue show a nonmagnetic state for Fe, while the Tb atoms carry a magnetic moment corresponding to a μelf of 9.25 μB.

Original languageEnglish
Pages (from-to)6056-6061
Number of pages6
JournalInorganic Chemistry
Volume41
Issue number23
DOIs
Publication statusPublished - Nov 18 2002

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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