The investigations of electronic structure, optical and magnetic properties of MgB<inf>2</inf> nanosheets

Abstract

First principles calculations were performed to study the electronic structures of Magnesium diboride (MgBz) bulk and nanosheet with different layer and thickness in order to understand the influence of layer number and thickness on electronic and optical properties for this compound, using the Full Potential Linearized Augmented Plane Waves (FP-LAPW) method with the Generalized Gradient Approximation (GGA) implemented in Wien2k code. It is shown that the MgBz is superconductor with Tc=39K, however MgBz sheet become a nonmagnetic semiconductor and good transparent in the visible range,the absorption coefficient decrease and the superconductor properties appears again with increasing number of layers.

Quantum confinement induced band gaps in MgB 2 nanosheets

“…It is well known that surfaces frequently introduce defect states into band gaps, and therefore it is common practice to use H to isolate the effects of quantum confinement from other effects, such as surface states. Interestingly, Zaari et al published calculations for an identical structure as Ao, without H atoms and using GGA, and reported a large band gap of 1.42 eV [28]. To settle the disagreement between Ao and Zaari, we have calculated the density of states for MgB 2 nanosheets without H, and confirm the results of Ao.…”

Nanoscale Mg–B via Surfactant Ball Milling of MgB2: Morphology, Composition, and Improved Hydrogen Storage Properties

“…The calculations predict that the electron density of states (DOS) at the Fermi level changes as one changes the MgB 2 morphology from bulk to nanosheet. − The B K-edge XAS for Mg–B Light (Figure ) reveals the elimination of the B 2p xy feature just above the Fermi level. However, it must be cautioned that the calculations do not include binding of oleate to Mg, nor the binding of H and OH to B, for which we expect a significant perturbation of the electronic structure.…”

“…The layered nature of the metal diborides (including MgB 2 ) has led previous workers to explore aqueous sonication as a means of exfoliating the structure, producing 2D “nanosheets”. − The nanosheets produced in these studies are laterally large, ∼3–6 μm, with a sheet thickness of order ∼2–10 nm. Surfactant ball-milling of graphite, boron nitride (BN), and molybdenum disulfide (MoS 2 ) also produces 2D nanosheets of the parent material. , These 2D materials have attracted theoretical interest as well, , particularly nanosheets derived from MgB 2 , − where the nanosheets are predicted to have modified electronic structure with implications for quantum-confinement and superconductivity …”