Effect of silica matrix on structural and optical properties of cobalt ferrite nanoparticles

Abstract

Effect of silica on structural and optical properties of cobalt ferrite nanoparticles is investigated. Silica matrix helps to reduce nanoparticle agglomeration. X-ray diffraction (XRD) and UV–Visible (UV–Vis) spectroscopic techniques are employed. XRD reveals pure phase formation with material density varying from 2.37 g cm−3 to 0.85 g cm−3. Energy band gap shows an escalation (2.03 eV to 4.89 eV) for change in silica from 0% to 90%. An empirical formula for refractive index as μ = A(silica content)2+B(silica content)+C has been derived using theoretical fit. With increase in silica content, the refractive index, optical dielectric constant and dielectric susceptibility show decrements from 2.65 to 1.83, 6.0225 to 2.3489 and 0.4795 to 0.1870 respectively. The reflectivity, absorption coefficient, molar refractive index, molar electronic polarizability, reflection loss, polaron radius and optical basicity also show reduction. Dielectric polarizability, transmission coefficient and oxygen packing density show increment from 0.33 Å 3 to 11.19 Å 3, 0.6606 to 0.8416 and 40.2114 to 34.2266. Ionic concentration of silica, metallization criterion also show similar incremental trend. Observed effects have been attributed to the change in interparticle interactions, density and microstructure of the samples. Swift changes in parameters indicate their fine tuning through optimum magnitude of silica.

Keywords

• Ferrite
• Silica
• Band gap
• Refractive index
• Polarizability
• Optical basicity