Nowotny Chimney Ladder Phases with Group 5 Metals: Crystal and Electronic Structure and Relations to the CrSi<sub>2</sub> Structure Type

oleh: Maxim S. Likhanov, Nikita V. Sytov, Zheng Wei, Evgeny V. Dikarev, Andrei V. Shevelkov

Format: Article
Diterbitkan: MDPI AG 2020-08-01

Deskripsi

Nowotny chimney ladder (NCL) phases are intermetallic compounds formed by transition metals and metals of groups 13 and 14. This family can be expanded by combining two <i>p-</i>elements from different groups with those transition metals, for which the corresponding binary NCL phases are unknown. In this paper, we present three new compounds in the V-Al-Ge, Nb-Al-Ge, and Nb-Ga-Ge systems related to the TiSi<sub>2</sub> structure type (Sp. Gr. <i>Fddd</i>) obtained with the standard ampule technique. The crystal structures of the new compounds were determined using synchrotron powder X-ray diffraction data. A transition to the CrSi<sub>2</sub> structure type was detected upon changing the composition from VAl<sub>0.72(2)</sub>Ge<sub>1.28(2)</sub> to VAl<sub>1.534(3)</sub>Ge<sub>0.466(3)</sub>. According to the 18–<i>n</i> rule, all the compounds are metallic conductors, which was supported by the electronic structure calculations. It was shown that the expected energy gap located above the Fermi level in the vanadium-based NCL compound collapsed into a pseudogap upon the replacement of V by Nb.