The new Zintl phases Eu{sub 21}Cd{sub 4}Sb{sub 18} and Eu{sub 21}Mn{sub 4}Sb{sub 18}
Crystals of two new Zintl compounds, Eu{sub 21}Mn{sub 4}Sb{sub 18} and Eu{sub 21}Cd{sub 4}Sb{sub 18} have been synthesized using the molten metal flux method, and their structures have been established by single-crystal X-ray diffraction. Both compounds are isotypic and crystallize in the monoclinic space group C2/m (No. 12, Z=4). The structures are based on edge- and corner-shared MnSb{sub 4} or CdSb{sub 4} tetrahedra, which make octameric [Mn{sub 8}Sb{sub 22}] or [Cd{sub 8}Sb{sub 22}] polyanions. Homoatomic Sb–Sb bonds are present in both structures. The Eu atoms take the role of Eu{sup 2+}cations with seven unpaired 4f electrons, as suggested by the temperature-dependent magnetization measurements. The magnetic susceptibilities of Eu{sub 21}Mn{sub 4}Sb{sub 18} and Eu{sub 21}Cd{sub 4}Sb{sub 18} indicate that both phases order anti-ferromagnetically with Néel temperatures of ca. 7 K and ca. 10 K, respectively. The unpaired 3d electrons of the Mn atoms in Eu{sub 21}Mn{sub 4}Sb{sub 18} do contribute to the magnetic response, however, the bulk magnetization measurements do not provide evidence for long-range ordering of the Mn spins down to 5 K. Electrical resistivity measurements suggest that both compounds are narrow band gap semiconductors. - Graphical abstract: Eu{sub 21}Mn{sub 4}Sb{sub 18} and Eu{sub 21}Cd{sub 4}Sb{sub 18} have complex monoclinic structures, based on MnSb{sub 4} and CdSb{sub 4} tetrahedra, both edge- and corner-shared. A perspective of the crystal structure is shown, as viewed along the b axis. Display Omitted - Highlights: • Eu{sub 21}Mn{sub 4}Sb{sub 18} and Eu{sub 21}Cd{sub 4}Sb{sub 18} are novel compounds in the respective ternary phase diagrams. • For both structures, the Zintl-Klemm rules are followed, and both are small gap semiconductors. • Eu{sub 21}Mn{sub 4}Sb{sub 18} and Eu{sub 21}Cd{sub 4}Sb{sub 18} are air-stable Zintl phases and could be new thermoelectric materials.
- OSTI ID:
- 22584134
- Journal Information:
- Journal of Solid State Chemistry, Vol. 238; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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