Synthesis and properties of hybrid hydroxyapatite–ferrite (Fe$_{3}$O$_{4}$) particles for hyperthermia applications

Hybrid ceramics consisting of hydroxyapatite Ca$_{10}$(PO$_{4}$)$_{6}$(OH)$_{2}$ and ferrite Fe$_{3}$O$_{4}$ were synthesized using a two-stage procedure. The first stage included the synthesis of Fe$_{3}$O$_{4}$ ferrite particles by co-precipitation and the synthesis of hydroxyapatite. In the second stage, the magnetic hybrid hydroxyapatite–ferrite bioceramics were synthesized by a thorough mixing of the obtained powders of carbonated hydroxyapatite and Fe$_{3}$O$_{4}$ ferrite taken in a certain proportion, pressing into tablets, and annealing in a carbon dioxide atmosphere for 30 min at a temperature of 1200$^\circ$C. The properties of the components and hybrid particles were investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Mössbauer spectroscopy. The saturation magnetization of the hybrid ceramic composite containing 20 wt % Fe$_{3}$O$_{4}$ was found to be 12 emu/g. The hybrid hydroxyapatite (Ca$_{10}$(PO$_{4}$)$_{6}$(OH)$_{2}$)–ferrite Fe$_{3}$O$_{4}$ ceramics, which are promising for the use in magnetotransport and hyperthermia treatment, were synthesized and investigated for the first time.