RESUMO
In this work, Zn(1-x)CaxFe(2)O(4) nanoparticles (x = 0, 0.5 and 1) have been synthesized by sol-gel method followed by heat treatment at a temperature within the range of 300-700 °C. The samples with appropriate saturation magnetization (Ms), low coercivity and remanence were Zn(0)Ca(1)Fe(2)O(4) treated at 300 °C (Ms ~ 25 emu/g), Zn(0)Ca(1)Fe(2)O(4) treated at 400 °C (Ms ~ 40 emu/g) and Zn(0.50)Ca(0.50)Fe(2)O(4) treated at 400 °C (Ms ~ 31 emu/g). These samples were analyzed by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and transmission electron microscopy. The heating ability of selected nanoparticles was evaluated under a magnetic field using a solid state induction heating equipment. The obtained nanoferrites showed a particle size within the range of 13-14 nm. The Zn(0)Ca(1)Fe(2)O(4) treated at 400 °C was able to heat the nanoferrite particles/water suspension (10 mg/2 ml) at a temperature of 44 °C under the selected magnetic field (10.2 kA/m and frequency 362 kHz). Additionally, in vitro bioactivity assessment was performed by immersing samples in a simulated body fluid for different periods of time at physiological conditions of pH and temperature. The samples showed an appropriate bioactivity. These nanoferrites are highly potential materials for hyperthermia treatment.
