Extended Data Fig. 6: Structural analysis of the monolayer Nb3Cl8 and Nb3SeI7.
From: Near-100% spontaneous rolling up of polar van der Waals materials
a, Schematic structure of monolayer Nb3Cl8. The black dash frame marks the tetrahedra of two sizes consisting of the Nb-triangles and the vertices Cl atoms. In the smaller tetrahedra, the Nb-Cl-Nb bond angle is 69.5°, the Nb-Cl bond length is 2.43 Å, and the Nb-Nb distance is 2.77 Å. Whereas the Nb-Cl-Nb bond angle is 96.4°, the Nb-Cl bond length is 2.69 Å, and the Nb-Nb distance is 4.01 Å in the larger tetrahedra. b, Schematic structure of monolayer Nb3SeI7. The black dash frame marks the tetrahedra of two sizes consisting of the Nb-triangles and the vertices atoms (I and Se). In the smaller tetrahedra, the Nb-Se-Nb bond angle is 75.5°, the Nb-Se bond length is 2.58 Å, and the Nb-Nb distance is 3.16 Å. Whereas the Nb-I-Nb bond angle is 97.7°, the Nb-I bond length is 2.96 Å, and the Nb-Nb distance is 4.46 Å in the larger tetrahedra.
