Ni7-delta SnTe2: Modulated crystal structure refinement, electronic structure and anisotropy of electroconductivity

作者：Isaeva A A; Baranov A I; Doert Th; Popovkin B A^*; Kulbachinskii V A; Gurin P V; Kytin V G; Shtanov V I

来源：Journal of Solid State Chemistry, 2007, 180(1): 221-232.

DOI：10.1016/j.jssc.2006.09.003

• metal-rich ternary chalcogenides
• modulated structure
• chemical bonding
• electroconductivity

Single crystals of Ni7-delta SnTe2 were grown during re-crystallization of the presynthesized powder in a two zone furnace. The modulated structure was solved and refined in the (3+2)-dimensional superspace group I4/mmm(0-alpha 0, alpha 00)0.ss.mm with lattice parameters a = 3.759(1) and c = 19.410(2) angstrom (measured at 153 K) and Z = 2. Satellite reflections observed in the diffraction images can be assigned to the incommensurate modulation vectors q(1) = da* and q(2) = db* with d = 0.410(1). The composition resulting from X-ray structure refinement is Ni5.81SnTe2. The structure model has been also developed in the orthorhombic (3 + 1)-dimensional superspace group Immm(alpha 00)00s assuming twinning according to [110], giving thus the composition Ni5.79SnTe2. The origin of the modulation can be attributed to a variation of the occupancy of the Ni(3) site in Ni/Te slabs of the structure. Band structure calculations on a commensurate approximant and single crystal electrical resistivity measurements reveal anisotropic metallic conductivity for this compound.

• 出版日期2007-1