Tailoring the structural and magnetic properties of Co-Zn nanosized ferrites for hyperthermia applications

Abstract

A comparative study of the magnetic properties (magnetic moment, magnetocrystalline anisotropy) and hyperthermia response in Co-Zn spinel nanoparticles is presented. The CoxZn1-xFe2O4 nanoparticles (x = 1, 0.5, 0.4, 0.3, 0.2 and 0.1) were synthesized by co-precipitated method and the morphology and mean crystallite size (around 10 nm) of the nanoparticles were analysed by TEM Microscopy. Regarding the magnetic characterization (SQUID magnetometry), Co-Zn nanoparticles display at room temperature anhysteretic magnetization curves, characteristic of the superparamagnetic behavior. A decrease in the blocking temperature, TB, with the Zn content is experimentally detected that can be ascribed to the reduction in the mean nanoparticle size as x decreases. Furthermore, the reduction in the magnetocrystalline anisotropy with the Zn inclusion is confirmed through the analysis of TB versus the mean volume of the nanoparticles and the law of approach to saturation. Maximum magnetization is achieved for x = 0.5 as a result of the cation distribution between octahedral and tetrahedral spinel

Impact of Co2+ Substitution on Microstructure and Magnetic Properties of CoxZn1-xFe2O4 Nanoparticles

“…They reported a ferromagnetic order at room temperature for all samples with an improvement in coercivity and saturation magnetization by increasing the concentration of Co 2+ in the host structure. These results contradict other findings obtained by Gomea-Polo et al [29], who investigated the same nanoferrite system prepared by the co-precipitation method. Their structure and magnetic study indicated that the particle size increases from 9.4 nm to 14.7 nm with the increase of the Co 2+ content from 0.1 to 1.0, with superparamagnetic behavior at room temperature.…”

Green Synthesis of Co-Zn Spinel Ferrite Nanoparticles: Magnetic and Intrinsic Antimicrobial Properties

“…This value is also affected due to antiferromagnetic order between magnetic cations in B sites since the B-B super-exchange interactions become more significant because of the breaking of the dominant A-B interactions. Spin canting arises when in B-sites concentration of non-magnetic ions becomes too high and can be explained in the frame of the Yafet-Kittel model [27,32,34]. Gómez-Polo and colleagues observed a divergence of the calculated value of magnetic moment by measured value of inversion degree by neutron diffraction which was enhanced when the concentration of zinc increased [34].…”

“…Spin canting arises when in B-sites concentration of non-magnetic ions becomes too high and can be explained in the frame of the Yafet-Kittel model [27,32,34]. Gómez-Polo and colleagues observed a divergence of the calculated value of magnetic moment by measured value of inversion degree by neutron diffraction which was enhanced when the concentration of zinc increased [34]. In our case trend becomes more pronounced in the region of 0.25 < x < 1 because of the change of the slope in the linear fitting of this region (4 − 3.6 x) × µ B .…”

Influence of shape, size and magnetostatic interactions on the hyperthermia properties of permalloy nanostructures

“…Different strategies have been adopted to tune hysteresis properties with the aim of increasing the relative heating contribution. A possible way is to use materials with high saturation magnetization and/or high uniaxial magneto-crystalline anisotropy, like cobalt or cobalt-zinc ferrites 19,22–26 . Another strategy consists in modifying nanostructure geometry, introducing shape anisotropies; promising results were obtained with magnetite nanorods 27 , maghemite, magnetite or cobalt ferrite nanocubes 28–30 and octahedral magnetite nanoparticles 31 .…”