Local Electronic Structure Perspectives of Nanoparticle Growth: The Case of MgO

Abstract

Herein, we reported nanoparticle growth from the point of view of the local electronic structure by taking MgO as a prototype material. These nanoparticles were obtained from the sol–gel autocombustion process. The precursor formed in this process was annealed for various temperatures ranging from 300 to 1200 °C for 0.5 and 1 h. It was observed that the amorphous phase occurred in the material synthesized at an annealing temperature of 300 °C for 1 h. This phase transformed to crystalline when the annealing temperature was increased to 350 °C. Crystallite size increased with annealing temperature; however, annealing time did not influence the crystallite size. To get deeper insights of modifications occurring at the atomic scale during crystallization growth, the local electronic structure of synthesized materials was investigated by measuring near-edge X-ray absorption fine structure at Mg, O, N, and C K-edges. These results envisaged that Mg 2+ ion coordination improved with the increase of annealing temperature. It was also observed that both annealing time and annealing temperature are sensitive to the local electronic structural changes.

X‐ray photoelectron spectroscopy characterization of band offsets of MgO/Mg2Si and SiO2/Mg2Si heterojunctions

“…It can be seen that the Mg 2p peak of MgO is located at 50.49 eV and the peak shape is very symmetrical, which indicates that the MgO film contains uniform Mg-O bond. This uniformity was also observed by Singh et al 34 and Liu et al 22 According to the linear extrapolation method, it can be deduced that the VBM of MgO is 2.72 eV, which is very consistent with the report of Liu et al 25 The energy difference between both is 47.77 eV. Figure 4c…”

“…where a oxide represents the lattice constant of MgO or SiO 2 , with values of 0.42 22 and 0.491 nm, 23 respectively; a Mg2Si represents the lattice constant of Mg 2 Si, with a value of 0.635 nm. 24 By substituting these values into Equation 1, the critical thickness of MgO and SiO 2 on Mg 2 Si is 0.41 and 0.837 nm, respectively.…”

Approaches to synthesize MgO nanostructures for diverse applications

“…Though, chemical methods are cost effective and known to provide better control over particle size and size distribution but the particles obtained by these methods are expected to have carbecanous impurities. These kinds of impurities are reflected from near edge X-ray fine structure [ 154 ] and Fourier transform infrared spectroscopy [ 155 , 156 , 157 ]. Though specific methodology is adopted by researchers to remove these nanoparticles to enhance their performance [ 158 ] but still their effect cannot be neglected.…”

Bottom-Up and Top-Down Approaches for MgO

“…Our group utilizes, this method to synthesize MgO nanoparticles using combustion synthesis while taking magnesium nitrate as an oxidizer and citric acid as fuel [68]. This method shows reproducibility [69]. The following equation is expected during synthesis process.…”

“…3 ) 2.4 H 2 O + Citric acid → MgO + CO 2 + NO + H 2 O Synthesis of MgO nanoparticles from magnesium nitrate Ref [69]…”