Vacancy ordered g Fe 2 O 3 nanoparticles functionalized with nanohydroxyapatite: XRD, FTIR, TEM, XPS and Mossbauer studies
Abstract Vacancy ordered maghemite (g Fe 2 O 3 nanoparticles functionalized with nanohydroxyapatite (HAp Ca 10 (PO 4 6 (OH) 2 have been successfully synthesized using an inexpensive co precipitation chemical route. Evidence for the presence of vacancy order in maghemite was shown by the superstructure lines observed in X ray diffraction. The adsorption of carboxyl groups of citric acid (C 6 H 8 O 7 onto g Fe 2 O 3 nanoparticles was investigated by FTIR, XPS and Mossbauer spectroscopy. From XPS surface analysis, two binding energies related to oxygen were attributed to bindings between C 6 H 8 O 7 /g Fe 2 O 3 and C 6 H 8 O 7 /HAp from an interfacial reaction promoted by strongly adsorbed H 2 O molecules at the surface of these nanomaterials. Le Bail refinement of the XRD patterns showed the formation of well crystallized pure tetragonal maghemite before and after functionalization with nanoHAp. The temperature dependence of hyperfine parameters of pure and functionalized g Fe 2 O 3 nanoparticles was investigated via Mossbauer spectroscopy. TEM revealed the formation of quasi spherical g Fe 2 O 3 nanoparticles with an average diameter of ca. 12 nm and 16 nm before and after functionalization with nanoHAp in agreement with Le Bail refinement. Magnetometry measurements showed a saturation magnetization of 12 emu/g and a blocking temperature of 340 K for the functionalized g Fe 2 O 3 nanoparticles.