Synthesis and characterization of fluorapatite–zirconia composite nanopowders

The structural and morphological features of fluorapatite–zirconia composite nanopowders during mechanochemical process and subsequent thermal treatment were investigated. The experimental outcomes were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDX), and field emission scanning electron microscopy (FE-SEM). After 300 min of milling, the average crystallite size, lattice strain, and the volume fraction of grain boundaries of fluorapatite were about 29 nm, 0.543%, and 9.64%, respectively. According to morphological evaluation, a fine homogeneous microstructure was obtained after 300 min of milling. The annealed sample at 600 °C exhibited grain size of about 32 nm for fluorapatite and 37 nm for monoclinic zirconia. During heating at 900 °C, fluorapatite decomposed to tricalcium phosphate (β-TCP) and calcium fluoride. With increase of temperature from 600 to 900 °C, the crystallite size of fluorapatite and monoclinic zirconia reached 43 and 40 nm, respectively. According to the FE-SEM micrographs, heat treated samples were composed of particles with a mean particle size of about 33 nm at 600 °C and 209 nm at 900 °C.