In the quest for
optimal heat dissipaters for magnetic fluid hyperthermia
applications, monodisperse M
x
Fe
3–
x
O
4
(M = Fe, Mg, Zn) spinel nanoferrites
were successfully synthesized through a modified organic-phase hydrothermal
route. The chemical composition effect on the size, crystallinity,
saturation magnetization, magnetic anisotropy, and heating potential
of prepared nanoferrites were assessed using transmission electron
microscopy (TEM), dynamic light scattering, X-ray diffraction (XRD),
thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy
(EDS), atomic absorption spectroscopy (AAS), X-ray photoelectron spectroscopy
(XPS), and vibrating sample magnetometer (VSM) techniques. TEM revealed
that a particle diameter between 6 and 14 nm could be controlled by
varying the surfactant ratio and doping ions. EDS, AAS, XRD, and XPS
confirmed the inclusion of Zn and Mg ions in the Fe
3
O
4
structure. Magnetization studies via VSM revealed both the
superparamagnetic nature of the nanoferrites and the dependence on
substitution of the doped ions to the final magnetization. The broader
zero-field cooling curve of Zn-doped Fe
3
O
4
was
related to their large size distribution. Finally, a maximum rising
temperature (
T
max
) of 66 °C was achieved
for an aqueous ferrofluid of nondoped Fe
3
O
4
nanoparticles
after magnetic field activation for 12 min.