Structural and electrical properties of a new ([SnSe]1.16)1(NbSe2)1 polytype

Abstract

A new polytype of the misfit layer compound ([SnSe] 1.16) 1 (NbSe 2) 1 with extensive rotational disorder was prepared from designed modulated elemental reactants. This polytype, previously referred to as a ferecrystal due to the extensive rotational disorder, formed over a range of compositions and precursor thicknesses and the resulting c-axis lattice parameters ranged from 1.2210(4) to 1.2360(4) nm. These values bracket the value published for the crystalline misfit compound prepared at high temperature. The a-and b-axis in-plane lattice parameters of both the SnSe and NbSe 2 constituents were incommensurate, which differs from the misfit layered compound formed via high temperature reaction that has a common b-axis lattice parameter for the two constituents. The in-plane area per unit cell of the ferecrystal is 1-2% larger than the compound formed at high temperature. The ferecrystalline ([SnSe] 1.16) 1 (NbSe 2) 1 compound is 1.6 times more conductive than the misfit layer compound. Hall effect measurements indicate that the ferecrystal is a p-type metal and that the higher conductivity is a consequence of higher mobility of carriers in the ferecrystalline compound.

Correlation of Reduced Interlayer Charge Transfer with Antiphase Boundary Formation in BixSn1–xSe–NbSe2 Heterostructures

“…Table contains the c ‐axis lattice parameters of each compound determined from the eight (00 l ) superlattice reflections visible in the 2 θ range of the diffraction scans. The c ‐axis lattice parameters of the two parent compounds, with x = 0 or 1.0, are consistent with those reported previously , . The trend in c ‐axis lattice parameter with composition is shown in Figure b.…”

Superconducting ferecrystals: turbostratically disordered atomic-scale layered (PbSe)1.14(NbSe2)n thin films

“…All of them exceed the θ D  = 150 K of the NbSe 2 single crystal30. Furthermore, Debye temperatures of about 200 K are typical for MLCs containing Nb X 2 20232526 and 240(3) K has been reported for the (SnSe) 1.16 (NbSe 2 ) ferecrystal31. If the phonon spectra are dominated by the NbSe 2 modes, then this suggests that the phonon spectra of ferecrystals and MLCs show only small differences, despite the structural distortions in the MLCs and the turbostratic disorder and decreased overall sample thickness of 40 nm of the ferecrystals.…”

Synthesis and Characterization of Quaternary Monolayer Thick MoSe2/SnSe/NbSe2/SnSe Heterojunction Superlattices

“…The c-lattice parameter obtained is 2.484(2) nm, which is close to that expected from the sum of the two parent compounds, (SnSe) 1.04 (MoSe 2 ) and (SnSe) 1.16 NbSe 2 . 25,26 As the electron density differences between Mo and Nb are slight, only differing by a single electron, the extent of intermixing cannot rigorously be determined using this method, but a best fit was obtained . The Rietveld refinement also revealed information regarding the puckering of the rock salt layers arising from interlayer attraction.…”