Properties of intercalated 2H-NbSe2, 4Hb-TaS2, and 1T-TaS2

Abstract

The layered compounds 2H-NbSe , 2 4Hb-TaS , 2 and 1T-TaS 2 have been intercalated with organic molecules; and the resulting crystal structure, heat capacity, conductivity, and superconductivity have been studied. The coordination in the disulfide layers was found to be unchanged in the product phase. Resistance minima appear and the superconducting transition temperature is reduced in the NbSe 2 complex. Conversely, superconductivity is induced in the 4Hb-TaS 2 complex. Corresponding evidence of a large change of the density of states, negative for 2H-NbSe 2 and positive for 4Hb-TaS 2 , was also observed upon intercalation. The transport properties of all the intercalation complexes show a pronounced dependence upon the coordination of the transition metal.

Synthesis and Characterization of Diamine Intercalation Compounds of SnS2 Single Crystals

“…These results are in contrast with those for in SnS treated with cobaltocene, the conductivity of which was found to signi"cantly increase on intercalation throughout the temperature range studied (180}300 K) (3). However, there is a remarkable similarity with those reported for NbSe intercalated with en (15). In this case, and although both systems exhibit a metallic behavior, a decrease in conductivity was measured upon intercalation the origin of which was explained in the light of the model of tunneling through a barrier.…”

“…The e!ect of the water is discussed below in describing thermal stability. The en complex was found to have an amine content higher than those of 1T}TaS (15) and 6R}TaS (16), the stoichiometry of which was TaS (en) , and somewhat greater than that reported for TiS , TiS (en) (17). However, we could not obtain a pure TiS -en complex under conditions similar to those for the SnS -en system (18).…”

Electronic structure of the chiral helimagnet and3d-intercalated transition metal dichalcogenideCr1/3NbSirica1, Mo2, Bondino3 et al. 2016Phys. Rev. B

“…Part of the broad appeal of layered TMDCs is that they are amenable to additional modification of their electronic structure [35]. One way this can be accomplished is through intercalation of a variety of electron donor species, ranging from alkali metals [36] to large organic molecules [37]. This drastically changes the carrier concentration of the host TMDC material and results in many nontrivial effects, including metal-to-semiconductor transitions [38], or semiconductor-to-superconductor transitions [39].…”

Low-temperature resistance minimum in non-superconducting 3R-Nb1+xS2and 3R-GaxNbS2

“…On intercalation, the T c in Ta compounds increases from < 1 K upto 5 K while it is lowered for Nb [5]- [9]. In self-intercalated 2H-Nb 1.05 Se 2 the T c was suppressed below 2.2 K [5], while 2H-NbSe 2 (EDA) 1/4 showed no superconductivity but a resistance minimum at ∼ 25 K [7]. Post-transition metal intercalated 2H-NbS 2 also did not show superconductivity [8].…”