Synthesis of CoFe₂O₄ Nanoparticles: The Effect of Ionic Strength, Concentration, and Precursor Type on Morphology and Magnetic Properties

Abstract

The present study highlights the effect of metal precursor types (SO42¯, Cl¯, and NO3¯), their concentration, and the influence of ionic strength of reaction environment on the morphology, surface, and magnetic properties of CoFe2O4 particles. The magnetic nanoparticles were obtained by chemical coprecipitation in alkaline medium at increasing metal concentration in the range of 0.0425 mol·dm-3 to 0.17 mol·dm-3 and calcination temperature from 400°C to 800°C. It was found that the chemistry of precursors can be directly correlated with magnetic properties. The CoFe2O4 particles from metal sulphate precursors showed the highest saturation magnetization and the lowest coercivity. The adjustment of ionic strength in the range of 1.25–5 M was achieved by adding an appropriate quantity of metal sulphates into aqueous solutions at a constant pH or by adding an appropriate quantity of NaClO5 under similar conditions. The average hydrodynamic size of CoFe2O4 increased from 46 nm to 54 nm with increasing metal concentration and ionic strength. An explanation of magnetic properties, caused by ionic strength and metal concentration, is given based mainly on the reduction in repulsive forces at the particle interface and compensation of the double electric layer in the presence of anions. The observed coercivity was lower for the particles obtained in solutions with the highest ionic strength, whereas the concentration of metals and calcination temperature affected the saturation magnetization and morphology of the obtained cobalt ferrite particles.

Extractive–Oxidative Desulfurization of Real and Model Gasoline Using (gly)3H[SiW12O40]⊂CoFe2O4 as a Recoverable and Efficient Nanocatalyst

“…The XRD patterns of (a–d) in Figure belong to CoFe 2 O 4 , SiW 12 O 40 , (gly) 3 H­[SiW 12 O 40 ], and (gly) 3 H­[SiW 12 O 40 ]⊂CoFe 2 O 4 , respectively. As can be seen in Figure a, several typical peaks at 2θ of ∼18, 30, 35, 37, 43, 53, 57, 65, 65, 73, and 77° display the spinel X-ray crystallography of the CoFe 2 O 4 nanoparticles (JCPDS No.00-003-0864). − Moreover, the XRD pattern of the CoFe 2 O 4 nanoceramics can be indexed according to the cubic spinel phase (space group Fd 3̅ m , a = 8.360(2) Å). The diffraction pattern of the Keggin-type silicotungstic acid (H 3 SiW 12 O 40 ) displays sharp and compressed peaks at 2θ of ∼18, 21, 24, 26, 31, 37, and 42° as indexed with the JCPDS card No.…”

Synthesis and potent antimicrobial activity of CoFe2O4 nanoparticles under visible light

“…The other advantage of CoFe 2 O 4 nanoparticles is one order higher of magnetocrystalline anisotropy compared to other reported metal ferrite nanoparticles with the same saturation magnetization. Thus, the relaxation time of magnetic CoFe 2 O 4 nanoparticles is much lower than other metal ferrite nanoparticles with similar particle size [ 4 , 5 ]. The specific surface area in Iron oxide nanoparticles is so high that they can interact with the surface structures of bacteria.…”

CoFe2O4@HaP as Magnetic Heterostructures for Sustainable Wastewater Treatment

“…The crystallite sizes of the three samples were calculated using the Debye–Scherrer equation [ 25 ]: D = (K × λ)/(B × cos θ B ); D = crystallite size (nm); K = constant dependent on the shape of the crystallite (0.89) (dimensionless); λ = wavelength of X-rays (nm) B = FWDHM (Full Width at Half Maximum) (degree) θ B = Bragg angle (degree). …”