The Synthesis and Characterization of Nickel and Cobalt Ferrite Nanopowders Obtained by Different Methods

Abstract

The single-phase NiFe 2 O 4 and CoFe 2 O 4 ferrites were synthesized by four methods: the high-frequency plasma chemical synthesis ("plasma"), sol-gel self-propagating combustion method ("combust"), and co-precipitation technology, combined with the hydrothermal synthesis ("hydrotherm") or spray-drying ("spray"). The specific surface area (SSA), crystallite size, and magnetic properties of the synthesized products have been determined. The synthesized ferrites are nanocrystalline single-phase materials with crystallite size of 5-40 nm. The SSA of nanoparticles synthesized in plasma is 28-30 m 2 /g, the particle size distribution is in the range of 10-100 nm, with some individual particles up to 200 nm. The SSA of the ferrites obtained by the self-combustion and hydrothermal synthesis is 40 ± 3 and 60 ± 5 m 2 /g, respectively. The SSA of the samples obtained by the spray-drying method is 80-90 m 2 /g, and the calculated particle size is 13-15 nm. In this process, pellets up to 10 μm are obtained. After synthesis, CoFe 2 O 4 are characterized by the saturation magnetization M s of 75 emu/g ("plasma"), 53 emu/g ("combust") and 57 emu/g ("hydrotherm"). The M s of NiFe2O4 is 44, 29, and 30 emu/g, respectively. The products obtained by the spray-drying method are partially X-ray amorphous and show magnetic properties only after heating above 450°C. These nanopowders were used in sintering studies.

Study of Kinetics and the Working Mechanism of Silica-Coated Amino-Functionalized CoFe2O4 Ferrite Nanoparticles to Treat Wastewater for Heavy Metals

“…Comparative hysteresis loops are shown in Figure . CoFe 2 O 4 nanoparticles were found to have high M s , M r , and H c values around 75 emu/g, 30 emu/g, and 1379 Oe, respectively, which are analogous to the findings of Zhang et al and Zalite et al When the calcination temperature increases, the defect in the material gradually diminishes and the thermal disturbance of atoms at the surface decreases. The regular alignment of the magnetic domains causes an increase in saturation magnetization .…”

Enhanced Relative cooling Power and large inverse magnetocaloric effect of cobalt ferrite nanoparticles synthesized by auto-combustion method

“…Accordingly, the synthesis methods are crucial in controlling magnetic properties of ferrites powders and their applications. CFO are typically elaborated using various methods including co-precipitation sol-gel, ceramic techniques and auto combustion utilizing different fuels [26]- [28]. Researchers have recently focused on the coupling between sol gel and auto combustion method, as it produced ferrite samples with high chemical homogeneity, good purity, and high crystallization.…”

Magnetic and Photocatalytic Properties of Nanodispersed Ferrites Co$_x$Ni$_y$Zn$_{1-x-y}$Fe$_2$O$_4$

“…Нині розроблено різноманітні технології одержання феритів. Як вихідну сировину використовують відповідні оксиди, солі, оксигідроксиди, карбонати, оксалати, цитрати [4][5][6][7]. Такі технології синтезу вимагають, зазвичай, використання високотемпературної обробки і складного апаратурного забезпечення [8,9].…”