A COMPREHENSIVE STUDY ON THE MICROSTRUCTURE AND OPTICAL PROPERTIES OF Fe3O4 NANOPARTICLES BY VARIATION OF TEMPERATURE AND NaOH CONCENTRATION

Abstract

This work was aimed at optimizing the microstructure and optical properties of Fe₃O₄ by variation of synthesis temperature and NaOH concentration. The nanoparticles have been synthesized from iron sand by using the coprecipitation method. The temperature was varied of 60^oC, 80^oC, and 100^oC, while NaOH concentration was 3 molar, 5 molar, and 7 molars. The microstructural parameters were characterized by using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques. The optical properties were characterized by using Fourier Transform Infrared Spectroscopy (FTIR) and UV-Vis Spectroscopy, consecutively. The results showed that the crystallite size of Fe₃O₄ increase with an increase of synthesis temperature due to higher thermal energy driving the nucleation process. The crystallite sizes are in the range of 3.77 nm – 20.37 nm. Increasing NaOH concentration also affected the increase in crystallite sizes. On the other hand, an excess of NaOH concentration influences the formation of smaller crystallite sizes of Fe₃O₄ with smaller crystal density and larger microstrain. The existence of Fe²⁺-O and Fe³⁺-O vibration in FTIR spectra confirmed the formation of Fe₃O₄ nanoparticles. The direct and indirect optical gap energies of Fe₃O₄ were in the range of 3.15 eV – 3.39 eV and 2.39 eV – 2.91eV. The synthesis temperature and NaOH concentration have a significant role in controlling the properties of Fe₃O₄.