Síntese e caracterização de ferritas mistas de níquel e cobre pelo método de complexação combinado EDTA/Citrato

Abstract

This paper consists in the synthesis and characterization steps to obtain a mixed nickel and copper ferrite (NixCu1-xFe2O4), in which the nickel’s presence varies from 0 to 100%, with gaps of 20% between each sample. As a synthesis route, complexation by EDTA and citric acid as chelating agents was the chosen method. Regarding the cationic precursors, hydrated iron, copper, and nickel nitrates were used, in stoichiometric proportions. The components were mixed at distinct temperatures, in alkaline medium, until a gelatinous substance was obtained, which was calcinated in two steps, the second one at 500, 600, and 700 ºC for different precursors’ samples. X-ray diffraction (XRD) analysis was performed on the samples following two procedures, at 5 and 0.2 degrees per minute, aiming to obtain the crystalline structure profile and to compare than with models from the X’Pert software and, then, refined on GSAS/EXPGUI. Two different scanning electron microscopy methods (SEM) were utilized, for two distinct magnification spectra: a desktop device and one with a field emission gun (FEG), attached to an energy dispersive spectroscopy (EDS). In both situations, imagens containing the synthetized ceramics were obtained and, aided by the EDS, it was possible to analyze the ratio between each ferrite’s atomic components. As a result, from the XRD analyses and refinement, it was possible to notice that the peaks present better definition at higher calcination temperatures, correspondence to the materials’ cards found on X’Pert and the absence of multiple phases on the products. Regarding the microscopies, the desktop device provided images with low resolution, because the synthetized materials has smaller dimensions than those of the method’s limitations. The SEM-FEG, on the other hand, allowed a better visualization of the particles, which is shaped, in some cases, as an octahedra structure. In order to evaluate the obtained solids’ usage, this paper recommends further characterization application studies.