Magnetic and hyperthermia properties of CoxFe3-xO4 nanoparticles synthesized via cation exchange

Abstract

We demonstrate magnetic and hyperthermia properties of CoxFe3-xO4 (x = 0, 0.1, 0.3 and 0.5) nanoparticles synthesized via a simple cation exchange reaction of ∼12 nm Fe3O4 nanoparticles. The substitution of Fe cations with Co2+ ions leads to enhanced magnetocrystalline anisotropy and coercivity of the pristine superparamagnetic Fe3O4 nanoparticles. Hyperthermia measurement shows that by controlling the Co content (x = 0 to 0.5) in CoxFe3-xO4 nanoparticles, their specific absorption rate (SAR) can be greatly improved from 132 to 534 W/g. The strong enhancement in SAR value is attributed to the increased anisotropy and coercivity. Moreover, with the increase of ac magnetic field from 184 to 491 Oe, the SAR values of Fe3O4 and Co0.5Fe2.5O4 nanoparticles increase from 81 to 132 W/g and 220 to 534 W/g, respectively.

Inductive Thermal Effect of Ferrite Magnetic Nanoparticles

“…Recent work has shown that because of the large magnetocrystalline anisotropy constant ( K = 2 × 10 5 J/m 3 ) of cobalt, it can be used to effectively tune the magnetic properties through the controlled doping of Co in Fe 3 O 4 , MnFe 2 O 4 and ZnFe 2 O 4 nanoparticles [97,98,99]. A systematic adjustment of Co stoichiometry in Co x Fe 3-x O 4 ( x = 0, 0.1, 0.3 and 0.5) NPs from 0 to 0.5 results in an increase in magnetic anisotropy and coercivity with maximum value reached x = 0.5 (see Figure 9C) [99,100]. The M S value of Fe 3 O 4 nanoparticles is 86 emu/g, and it is decreased to 82, 78 and 77 emu/g, respectively with the increase of Co 2+ ion concentration due to the smaller magnetic moment of Co 2+ (3 µ B ) as compared to Fe 2+ (4 µ B ) [91].…”

“…( B ) Blocking temperature vs. NPs size plot indicates a linear relationship between blocking temperature and NPs size [92]. ( C ) Hysteresis curves of Co x Fe 3- x O 4 nanoparticles with x = 0, 0.1, 0.3 and 0.5 at 10 K [100]. ( D ) Dependences of M S on the Zn and Co substitution content ( x ) in Fe 3 O 4 nanoparticles [99,102].…”

Exploring the effect of Co concentration on magnetic hyperthermia properties of CoxFe3−xO4 nanoparticles

“…The methods widely used for the synthesis of magnetic Co x Fe 3−x O 4 NPs are as follows: co-precipitation, hydrothermal, reverse micelle, sol-gel, etc [39,40]. By doping Co ions into Fe 3 O 4 powders, Mohapatra et al [41] synthesized Co x Fe 3−x O 4 (0 <× 0.5) NPs, and performed hyperthermia measurements by applying various alternating magnetic fields. In this regard, increasing the intensity of the magnetic field from 184 to 491 Oe resulted in an increase in SLP from 81 to 132 W g −1 and 220 to 534 W g −1 for ferrofluids (having a concentration of 2 mg ml −1 ) of Fe 3 O 4 and Co 0.5 Fe 2.5 O 4 NPs, respectively.…”

“…While widespread research has been performed in the field of magnetic hyperthermia for materials such as Fe 3 O 4 and some ferrites, less attention has been paid to FORC investigations and the effect of Co concentration on magnetic hyperthermia properties of Co x Fe 3−x O 4 compound. In other words, the limited literature in this area is mainly focused on the investigation of structural and absorption properties of ferrites [10,12,41,[43][44][45][46].…”

The effect of magneto-crystalline anisotropy on the properties of hard and soft magnetic ferrite nanoparticles

“…Among ferrites, CoFe 2 O 4 NPs are of considerable interest because of their moderate saturation magnetization, good chemical stability and high intrinsic magnetocrystalline anisotropy at room temperature [10]. The anisotropy constant of CoFe 2 O 4 ( K = 2 × 10 5 J·m −3 ) is nearly one order of magnitude larger than that of Fe 3 O 4 [11–13]. Fe 3 O 4 NPs have been studied extensively for bio-medical applications, such as drug delivery [14], magnetic resonance imaging (MRI) and especially magnetic hyperthermia therapy, which is one of the efficient and new approaches for cancer treatment [4,15].…”