Synthesis and Structure of Quasi-One-Dimensional Niobium Tetrasulfide NbS₄

Abstract

The binary niobium sulfide NbS 4 was synthesized as a crystalline phase. We showed that NbS 4 can be formed from Nb metal, from defect niobium sulfide Nb 1.14 S 2 , or from some other niobium dichalcogenides in reactions with excess sulfur in an evacuated ampule at 440 °C. The crystal structure of NbS 4 (monoclinic space group C2/c, a = 13.126(2) Å, b = 10.454(1) Å, c = 6.951(1) Å, β = 111.939(5)°) is a packing of infinite chains {NbS 4 } 1∞ , analogous to VS 4 . In the chains, Nb atoms are in a tetragonalantiprismatic coordination of sulfur atoms of disulfide groups (S 2 ) 2− ; short Nb•••Nb contacts (2.896 Å) alternating with longer ones (3.278 Å) appear within the chains at 150 K. According to density functional theory calculations, NbS 4 is a thermodynamically stable compound, a nonmagnetic semiconductor. NbS 4 is a new member of the family of quazione-dimensional compounds, group 5 metal polychalcogenides, well-known for their interesting electrophysical properties. The synthesis and crystal structure as well as the thermal stability and lattice dynamics of NbS 4 are discussed here.

Emerging quasi-one-dimensional material NbS4 with high carrier mobility and good visible-light adsorption performance for nanoscale applications

“…For the narrow spacing, nearly itinerant electrons connect them as well as neighbouring S atoms, confirming previous assumptions about covalent bonds between Nb atoms. 29 The 1D chain actually employs the structure of [Nb 2 S 8 ] as periodic repeating units, where the dimerized S atoms are pairwise bonded with a valence of −1, and Nb 4+ close to each other form covalent bonds. The intricate interactions of the vdW bond, nonmetallic atom dimerization, and metal atom covalent bond form the non-magnetic state of transition metal tetrasulfide.…”

“…However, NbS 4 has not been synthesized for a long time, and it is speculated that NbS 4 belongs to the VS 4 configuration, until recently, Anastasiia Poltarak et al successfully synthesized NbS 4 crystals and added a new member to the family of quasi-1D transition metal chalcogenides. 29 As shown in Fig. 1, the Nb atoms are located in tetragonal antiprisms of sulfur atoms and form infinite chains of NbS 4 with alternating NbÁ Á ÁNb distances.…”

“…[26][27][28] Group V metals tend to form quasi-1D trichalcogenides and tetrachalcogenides. 29 The vdW spacing between the quasi-1D chain structural blocks can promote intercalation, resulting in charge density waves and superconductivity. 30 Type-III Weyl points 31 and Peierls transition driven by the instability of the Fermi surface 32 exist in (TaSe 4 ) 2 I consisting of TaSe 4 chains.…”

“…However, NbS 4 has not been synthesized for a long time, and it is speculated that NbS 4 belongs to the VS 4 configuration, until recently, Anastasiia Poltarak et al successfully synthesized NbS 4 crystals and added a new member to the family of quasi-1D transition metal chalcogenides. 29 NbS 4 crystallizes in monoclinic space group C 2/ c with cell parameters a = 13.126 (2) Å, b = 10.454 (1) Å, c = 6.951 (1) Å, β = 111.939 (5) °. As shown in Fig.…”

NbTe4 Phase‐Change Material: Breaking the Phase‐Change Temperature Balance in 2D Van der Waals Transition‐Metal Binary Chalcogenide

“…A similar band structure in this region was also reported for DFT simulations of NbS 4 , showing a similar quasi‐1D crystal structure to NbTe 4 . [ 43 ] While the Nb 4d band in crystallization becomes sharper at 2 eV with a decrease of DOS in the region from 0 to 1 eV. Thus, the abnormally high resistance caused by the crystallization of NbTe 4 can be attributed to the reduction of Nb 4d orbitals near the Fermi level, which might be associated with the disappearance of Nb clusters by crystallization.…”