Structural, Optical, and Dielectric Properties of Aluminum Oxide Nanofibers Synthesized by a Lower-Temperature Sol–Gel Approach

Abstract

is the most versatile and important ceramic material, having applications in various fields including electronic devices. It is stable at high temperatures and is chemically inert. The sol-gel method, a relatively lowertemperature technique, has been used to synthesize aluminum oxide nanofibers. The molarity of the sol concentration was varied as 0.7 M, 0.8 M, 0.9 M, 1.0 M, and 1.1 M. The structural, optical, and dielectric properties of the assynthesized nanofibers were characterized. x-ray diffraction (XRD) analysis results confirmed formation of a-Al 2 O 3 phase of aluminum oxide, notably without any heat treatment or use of water as solvent. The crystallite size and unit cell volume of the nanofibers increased as the sol concentration was increased to 0.9 M, but further increase in sol concentration resulted in reduction of crystallite size and increase in dislocations. Scanning electron microscopy (SEM) results revealed uniform distribution of nanofibers ($25 nm to 30 nm) under all conditions. Nanofibers prepared using sol concentration of 0.9 M showed high transmission ($89%) in the visible and infrared regions. The energy bandgap varied from 3.69 eV to 4.1 eV with the variation in molar concentration. Lower bandgap correlated with defect-induced states in the bandgap. The high refractive index is indicative of high density of aluminum oxide nanofibers. High grain-boundary resistance (1.455 MX) and high dielectric constant ($15.76) along with low tangent loss were observed at molar concentration of 0.9 M.

Application of Alumina Nanofibers as Adsorbents for the Removal of Mercury (II) and Lead (II) from Aqueous Solutions

“…Minerals 2023, 13, x 6 of 19 dimensions of the prepared nanofibers which range in length up to ~ 500 nm and are ~ 25 nm wide. Similar to Riaz et al, who reported diameters of 25 to 30 nm, using a lower temperature sol-gel method to synthesize gamma alumina nanofibers [34]. Figure 1a micrograph of the nanofibers before adsorption shows that they consist of a random-distribution, mesh structure.…”

Tailoring TiO2/Al2O3 heterolayers as optical filters for the visible region

“…In the range of 300–350 nm, the change in the extinction coefficient with wavelength was very small and there was no visible change in the extinction coefficient values with wavelength after 350 nm. 37 The change in the relations between the extinction coefficients and refractive indices with the wavelength in the graph were almost the same. For TiO 2 , the value of refractive index increased as the wavelength changed from 300 to 358 nm.…”

Structural Characterization and Dielectric Properties of the Effect of Carbon Nanotubes and Silicon on AA2024 Metal Matrix Composites

“…From the results obtained, AA 2024 + 4% CNT + 2% Si composites shows low dielectric constant and low dielectric loss. Dielectric materials with low-loss are widely employed in communication systems and also in quite a lot of electronic devices [34][35][36][37].…”