2D metal slabs in new nickel–tin chalcogenides Ni7−δSnQ2 (QSe, Te): average crystal and electronic structures, chemical bonding and physical properties

New metal-rich mixed chalcogenides with an intergrowth structure: Ni5.68SiSe2, Ni5.46GeSe2, and Ni5.42GeTe2

“…3 In the X ray diffraction patterns for the faces perpendicular to the pressure direction, the in tensities of the (00l) zone reflections are higher than those of the (hk0) zone reflections. To the contrary, the intensi ties of the (hk0) zone reflections are substantially higher in the X ray diffraction patterns of the faces that are par allel to the pressure direction.…”

“…14 The lengths of the homometallic Ni-Ni bonds are, on the whole, substantially larger than those in nickel metal (2.489 Å) 15 and are comparable with the corresponding bond lengths in the intermetallics Ni 3 E and telluride Ni 2.86 Te 2 (2.666 and 2.674 Å, respectively). 16 The short est Ni-Se distances (Ni(3)-Se bonds parallel to the c axis) are slightly shorter than those found in the binary selenides (cf., 2.29-2.5 Å in Ni 3 . In all structures, the E-E and X-X interatomic distances are larger than 3.6 Å, and, consequently, these interactions are nonbonding.…”

“…Crystallites of both phases are thin platelets and, con sequently, their larger faces should be arranged perpendicular to the load direction. 3 The electron diffraction study showed 3 that the c axis is perpendicular to the larger face of the crystallites, resulting in the anisotropy of the conductivity of the pellets along different directions. To confirm the texturization of the samples, the X ray powder diffraction study on a Bruker D8 Discover diffractometer equipped with a GADDS area detector (CuKα 1 radiation, reflection mode, pyrographite monochroma tor) was performed for the pellet faces parallel and perpendicu lar to the pressure direction.…”

“…2) and Ni 5.75 SnSe 2 (see Ref. 3) revealed the difference in the nature of chemi cal bonding in two types of slabs. The heterometallic slabs are characterized by multicenter interactions, whereas pairwise interactions are present in the d metal chalcogenide slabs.…”

Ni7−δSnTe2: Modulated crystal structure refinement, electronic structure and anisotropy of electroconductivity

“…Among these, Ni 5.72(3) SbSe 2 , Ni 5.66(2) SbTe 2 [1], Ni 5.98(3) SnS 2 , Ni 8.93(1) Sn 2 S 2 [2], Ni 5.62(1) SnSe 2 , Ni 5.78(2) SnTe 2 [3] and the solitary palladium analog Pd 6.21(1) SnTe 2 [4] have to be mentioned. The crystal structures of these compounds are composed of hetero- While all other structures were solved in space group I4/ mmm, the modulated structure of the palladium compound Pd 6.21(1) SnTe 2 was refined in the (3+2)-dimensional superspace group I4/mmm(0-a0, a00)0.ss.mm with the modulation vectors q 1 ¼ da* and q 2 ¼ db* with d ¼ 0.4 using the superspace formalism [4].…”