Syntheses and Structures of Sc2Nb4–xSn5, YNb6Sn6, and ErNb6Sn5: Exploratory Studies in Ternary Rare-Earth Niobium Stannides

Three new rare-earth (RE) niobium stannides, namely, Sc2Nb4–xSn5 (x = 0.37, 0.52), YNb6Sn6, and ErNb6Sn5, have been obtained by reacting the mixture of corresponding pure elements at high temperature and structurally characterized by single-crystal X-ray diffraction studies. Sc2Nb4–xSn5 crystallizes in the orthorhombic space group Ibam (No. 72) and belongs to the V6Si5 type. Its structure features a three-dimensional (3D) network composed of two-dimensionally (2D) corrugated [Nb2Sn2] and [Nb2Sn3] layers interconnected via Nb–Sn bonds, forming one type of one-dimensional (1D) narrow tunnels along the c axis occupied by Sc atoms. YNb6Sn6 crystallizes in the hexagonal space group P6/mmm (No. 191) and adopts the HfFe6Ge6 type, and ErNb6Sn5 crystallizes in the trigonal space group R3̅m (No. 166) and belongs to the LiFe6Ge5 type. Their structures both feature 3D networks based on 2D [Nb3Sn], [Sn2], and [RESn2] layers (RE = Y, Er). In YNb6Sn6, one type of [Nb3Sn] layer is interconnected by [Sn2] and [YSn2] layers via Nb–Sn bonds to form a 3D network. However, in ErNb6Sn5, two types of [Nb3Sn] layers are interlinked by [Sn2] and [ErSn2] layers via Nb–Sn bonds into a 3D framework. Electronic structure calculations and magnetic property measurements for “Sc2Nb4Sn5” and YNb6Sn6 indicate that both compounds show semimetallic and temperature-independent diamagnetic behavior.