Caracterização estrutural e optica das nanopartículas da magnetita (Fe3O4)

Abstract

Magnetite (Fe₃O₄) stands out among iron oxides for its structural, magnetic, and optical properties, especially when structured on a nanometric scale. In this work, the structural and optical properties of Fe₃O₄ nanoparticles synthesized by the coprecipitation method were investigated at drying temperatures ranging from 40 °C to 120 °C, to analyze the influence of this variable on the final characteristics of the material. Structural characterization was performed by powder X-ray diffraction (XRD), which allowed the identification of the crystalline phase associated with the inverse spinel structure. Compositional analyses were conducted using Scanning Electron Microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), confirming the presence of the constituent elements. Optical characterization was performed using UV Vis absorption spectroscopy in the 450 to 1000 nm range, allowing the evaluation of the absorption profile of the nanoparticles. Additionally, the thermal lens technique was employed to investigate the conversion of light energy into heat, enabling the determination of thermal diffusivity and the phase variation induced by heating the medium. The results confirmed the formation of the magnetite phase and indicated that variations in drying temperature influence optical parameters, probably associated with structural changes (not discussed), highlighting a correlation between crystallinity and photothermal behavior. Keywords: magnetite; nanoparticles; coprecipitation; X-ray diffraction; UV Vis; thermal lens.