Charge Transfer between PbSe and NbSe₂ in [(PbSe)_1.14]_m(NbSe₂)₁ Ferecrystalline Compounds

Abstract

PbSe) 1.14 ] m (NbSe 2 ) n compounds with 1 ≤ m ≤ 6 and n = 1 were synthesized using the modulated elemental reactants (MER) method. X-ray diffraction patterns (XRD) showed that the desired compounds self-assembled during annealing of the precursors with their c-axis crystallographically aligned normal to the substrate. The c-axis lattice parameter increased by 0.612 nm as m, the number of PbSe bilayers, increased by one. Analysis of the in-plane diffraction patterns indicated that the a-lattice parameters remained constant as m was varied. Reciprocal space maps along hkl (h, k ≠ 0; l ≠0) indicate very short coherence lengths in mixed-index directions, consistent with the rotational disorder between layers observed in electron microscopy cross sections. The in-plane electrical resistivity and Hall coefficients were measured for each ferecrystal from 22 to 295 K. The resistivity systematically increased as m increased, but the magnitude of the increase is greater than predicted assuming independent layers. Assuming the metallic conduction results from a single band in the NbSe 2 layer, the carrier concentrations determined from the Hall coefficients decreases as m increases, suggesting increased charge transfer from PbSe to NbSe 2 with increasing values of m. First-principles electronic-structure calculations based on the generalized gradient approximation to density functional theory suggest that the PbSe valence band overlaps the empty bands in NbSe 2 , supporting the idea of interlayer charge transfer from PbSe to NbSe 2 .

Influence of interstitial V on structure and properties of ferecrystalline ([SnSe]1.15)1(V1+Se2)n for n=1, 2, 3, 4, 5, and 6

“…For the ferecrystalline compounds the carrier concentration increases systematically as a function of n. However, comparing the carriers/V-atom based on the composition from EPMA results in an almost constant carrier concentration/V-atom at room temperature for compounds with n > 2. Only for the (1,1) and (1,2) compound the carriers/V-atom remain below 1, suggesting charge transfer between the constituent layers [29].…”

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

“…Due to strain, epitaxial growth is limited to few stacking sequences and does not exist for thin extended films. Instead, for ferecrystals a manifold of stacking sequences is possible, because no epitaxial relationship is given for subsequent atomic planes in growth direction14.…”

“…Ferecrystals are prepared by self-assembly of designed precursors1415161718. Their synthesis method has been developed only recently.…”

Density functional theory calculations of the turbostratically disordered compound[(SnSe)1+y]m(VS

“…[6][7][8] A change from 3D to 2D has also been shown to lead to changes in interlayer coupling, the degree of quantum confinement and in electronic structures. 9 The intriguing properties of nanocomposites arise in many different ways: from how the constituents' properties interact, 10 from the effects of the nanoscale dimensions on the constituents, 8 or from the interface effects amplified by the nanoscale dimensions. 11,12 Understanding the source of the properties ideally leads to the ability to experimentally control them and also to the ability to predict what composites might best serve in a specific technological application.…”