Clean and metal-doped bundles of boron-carbide nanotubes: A density functional study

Abstract

Carbon nanotubes and many types of inorganic nanotubes can be produced in the form of hexagonal arrays or bundles. In this paper, we discuss results of ab initio density functional theory calculations on the stability, and atomic and electronic structure, of bundles of narrow, clean, and Li-and Cu-doped, boron-carbide nanotubes related to LiBC and CuBC layered compounds. We find that covalent bonding arises between neighboring tubes in the bundles which results in the formation of complex structures. We show that a high concentration of dopant Li atoms in the bundles can be achieved by a combination of in-tube and interstitial doping. A high concentration of Li atoms involving only in-tube doping is energetically unfavorable due to repulsive interaction between the Li atoms. By contrast, increased doping with Cu atoms can produce a metallic wirelike structure along the longitudinal axis of each tube within the bundle.

Electronic Structures and Properties of Bimetallic Plutonium Group 13 Carbonyl Compounds [XPuCO] (X = B, Al, and Ga)

“…Significantly, the σ-donation AlC → Pu­(O) into the vacant Pu ρ­(5f) AOs is weaker than the π-donation AlC → Pu­(O) into the vacant Pu ρ­(6d) AOs because C 2p-based MOs have less overlap with the sharply contracted 5f AOs of Pu­(V) than with the 6d AOs. There have been previously reported examples such that π-donation is stronger than σ-donation in transition-metal-doped boron carbide complexes . Also, the stronger stabilization of the AlC → Pu­(O) donations than the AlC ← Pu­(O) backdonations comes from the larger electron density of AlC than that of Pu with the donor ρ­(σ) and ρ­(π) orbitals.…”

“…For example, the use of gallium as an alloying element in the manufacture of plutonium pits could increase the phase stability in plutonium, giving rise to many theoretical studies of PuGa. − Since boron atoms can form strong covalent bonds with many elements such as transition-metal elements and lanthanides, this makes it possible to find new materials with novel properties and excellent performance of boron-based systems. In recent years, molecular and crystal plutonium borides have been reported, such as PuB, PuB 2 , PuB 6 , and PuB 12 . − …”

Developments in Direct CH Arylation of (Hetero)Arenes under Microwave Irradiation

“…Since then, a few investigations on the properties of LiBC, including lattice dynamics, electronic and optical properties, vibrational properties, elastic properties, and high pressure properties, have been carried out theoretically and experimentally 11–20. So far many attempts by metal‐doping or applying pressure to induce an insulator–metal transition and possible superconductivity have not shown any convincing experimental evidence 21–23. However, it is acknowledged that the electron–phonon coupling plays an important role in the superconductivity of LiBC 12, 24.…”

Electronic structure and thermodynamic properties of LiBC under high pressure

“…[3] Since then, a few investigations on the properties of LiBC, including lattice dynamics, [4,5] electronic and optical properties, [6−8] vibrational properties, [9−11] elastic properties, [12] and high pressure properties, [13] have come to the fore theoretically and experimentally. Recently attentions are centralized on how to produce an insulatormetal transition and possible superconductivity, one way is by metal-doping, [14] and the other is applying pressure [15] which is not successful experimentally.…”