X-ray absorption study of the local structure of Mg in hydroxyapatites thin films deposited by RF magnetron Co-Sputtering

Mg-doped hydroxyapatite (HAp) were deposited on Ti-6Al-4V substrates by radiofrequency (RF) magnetron co-sputtering of HAp and Mg targets. The as-deposited films were amorphous. Therefore, they were annealed at 1000 degrees C in ambient air. After annealing, the crystal structure, local structure, coatings morphology, and composition were investigated by X-ray diffraction technique (XRD), X-ray absorption spectroscopy (XAS), scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDX), respectively. The XRD results show the amorphous phase for as-deposited and the major phase of TiO2 with a few secondary phase. The Mg K-edge XANES spectra was examined in order to identify the local site of Mg in hydroxyapatite thin films, which is formed as MgO in as-deposited sample and as MgAl2O4 in annealed sample. The information on the locally determined structures were obtained and discussed. The surface morphologies show the spherical shape particles with uniform distribution on the surface and new agglomeration of particles of MgAl2O4 on the surface of asdeposited and annealed samples, respectively.