Mössbauer studies of composites hydroxyapatite/ferroxides

Magnetic composite (MC) particles consisting of finding hydroxyapatite and iron oxides (HAp/FeOxid), synthesized at both pyrolysis temperatures during MC synthesis, i.e., 800, 900, and 1000$^{\circ}$C and at the various ferroxide concentrations in the HАp : FeOxid composite, i.e., 1 : 3, 1 : 2, and 1 : 1 (at a pyrolysis temperature of 1000$^{\circ}$C). It is found that the HAp/FeOxid MCs are formed by the hydroxyapatite matrix providing biological compatibility of the MC containing iron oxide particles. Mössbauer studies show that maghemite ($\gamma$-Fe$_2$O$_3$), magnetite (Fe$_2$O$_3$), $\varepsilon$-Fe$_2$O$_3$, and akaganeite ($\beta$-FeOOH) phases are simultaneously observed in synthesized HAp/FeOxid MCs. The content of $\varepsilon$-Fe$_2$O$_3$ component having giant magnetic anisotropy is to $\sim$40% of iron oxides (FeOxid) in HAp/FeOxid MCs, which makes obtained MCs very promising for various applications, including biomedical ones.