Effect of Lanthanide Metal Complexation on the Properties and Electronic Structure of Single-Walled Carbon Nanotube Films

Abstract

We spectroscopically analyze the effect of e-beam deposition of lanthanide metals on the electronic structure and conductivities of films of semiconducting (SC) single-walled carbon nanotubes (SWNTs) in high vacuum. We employ near-infrared and Raman spectroscopy to interpret the changes in the electronic structure of SWNTs on exposure to small amounts of the lanthanides (Ln = Sm, Eu, Gd, Dy, Ho, Yb), based on the behavior of the reference metals (M = Li, Cr) which are taken to exemplify ionic and covalent bonding, respectively. The analysis shows that while the lanthanides are more electropositive than the transition metals, in most cases they exhibit similar conductivity behavior which we interpret in terms of the formation of covalent bis-hexahapto bonds [(η(6)-SWNT)M(η(6)-SWNT), where M = La, Nd, Gd, Dy, Ho]. However, only M = Eu, Sm, Yb show the continually increasing conductivity characteristic of Li, and this supports our contention that these metals provide the first examples of mixed covalent-ionic bis-hexahapto bonds [(η(6)-SWNT)M(η(6)-SWNT), where M = Sm, Eu, Yb].

The coordination chemistry of oxide and nanocarbon materials

“…176,177 Indeed, complexes of graphene and SWCNTs were synthesized with Mo and W, 178 first row metals (Ti, V, Cr, Mn, Fe), 23 and the lanthanides (Ln = Sm, Eu, Gd, Dy, Ho, Yb). 179,180 However, not all carbon nanomaterials form similar (η 6 -C n ) 2 M interconnects. For example, orbital misalignment in fullerenes prevents formation of (η 6 -C n ) 2 M interconnects described above.…”

(Invited) Effect of Covalent Chemistry on the Electronic Structure and Properties of the Carbon Allotropes

“…However the deposition of the lanthanide metals on SWNT films resulted in two different trends in the conductivity () enhancement illustrated in Figure 4: (i) enhancement less than Cr and fairly typical of other transition metals in the case of Ln = La, Nd, Gd, Dy, Ho, and (ii) enhancement that exceeded or matched the Cr values for Ln = Sm, Eu, Yb (15,29). The lanthanide conductivity data was rationalized by reference to a model based on the accessibility of the 4f m 5d 1 6s 2 electronic configuration for the individual lanthanide atoms (30,31).…”

Lanthanides: The Key to Durable and Sustainable Corrosion Protection

“…The lanthanide group elements (Ln), also known as rare earth elements (REEs), are the “nutrients” of metals and “vitamins” of modern industry and have the ability to improvise the intramural aspects of metals (alloy formation, hardness, and strength) and have been extensively employed in various fields including microelectronics, aeronautics, automotive, medical, chemical, and metallurgical engineering. , Furthermore, the novelty of Ln having unpaired electrons in f-orbitals also intercalates an influential impact on extraneous properties of metals by depositing on the surface. , With deposition, the limited radial extension affiliated with these f-orbitals, having a negligible effect on the chemistry of the interaction process, provides multiple ways and reaction sites to intermingle with the substrate surface . The half-filled orbitals connected with paramagnetic, diamagnetic, and ferromagnetic behavior additionally insert electromagnetic and optical properties in the lanthanides. , Accompanying all these aspects, coatings of Ln elements have been recently adopted as an effective replacement for highly toxic and carcinogenic chromate coatings that have the ability to modify both the physical and chemical properties of metals. − There is striving to search for chromate-free coatings that resulted in many procedures that involved phosphate, molybdates, silicates, titanium, and borate coating procedures, which produced both types of positive and negative alterations in surficial properties .…”

“…1,2 Furthermore, the novelty of Ln having unpaired electrons in f-orbitals also intercalates an influential impact on extraneous properties of metals by depositing on the surface. 3,4 With deposition, the limited radial extension affiliated with these f-orbitals, having a negligible effect on the chemistry of the interaction process, provides multiple ways and reaction sites to intermingle with the substrate surface. 5 The half-filled orbitals connected with paramagnetic, diamagnetic, and ferromagnetic behavior additionally insert electromagnetic and optical properties in the lanthanides.…”