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Embedded-style hydroxyapatite-titania nanotube arrays were successfully prepared by anodic oxidation of titanium substrate and centrifugal filling hydroxyapatite precursor sol into hollow nanotubes. The morphology, microstructure and thermal stability of the samples were characterized by X-ray diffraction, environmental scanning electron microscopy, and energy dispersive X-ray analysis. The results show that the structure of titania nanotube arrays is stable at 500 °C or below, and the crystallized hydroxyapatite could be formed from hydroxyapatite precursor sol after calcining at 500 °C for 4 h. The optimum calcining temperature for this material is 500 °C. An obvious apatite layer formed on the surface of the embedded-style material after soaking in simulated body fluid for 5 days, indicating that the material possesses a good in vitro apatite forming ability on its surface. [ABSTRACT FROM AUTHOR]

Needle-like nanocarbonated hydroxyapatite (CHA) powders were prepared by hydrothermal method using Ca(NO3)2, (NH4)3PO4 and urea as reagents. Element analyse (EMA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermogravimetry differential thermogravimetry (TG-DTA) were used to characterise the crystalline phase, microstructure, chemical composition, morphology and thermal stability of CHA. The results show that AB type CHA can be obtained through this method. The carbonate content and the ratio of length to diameter of CHA can be adjusted by controlling the concentration of urea. The results show that CO32-incorporated into the apatite structure has an influence on the properties of CHA, such as the morphology and the size of crystal grain, the lattice parameters and the unit cell volume and the crystallisation degree and the stability. [ABSTRACT FROM AUTHOR]

Based on the principles of biomineralisation, spindle shaped hydroxyapatites (HA) were synthesised through the biomimetic method with chitosan (CS) as template. The microstructure, chemical composition and thermal behaviour were characterised by means of X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and thermogravimetry differential thermal analysis (TGDTA) respectively. The results show that the spindle shaped nanoHA, 30–40 nm in length and 7–8 nm in width, were synthesised with 0·5 wt-%CS as template in 6% (v/v) hydrogen peroxide solution for 7 days. The crystallinity of samples increased with the aging time. TGDTA analyses show that the HA powders synthesised with CS as template contain CS molecules and have good thermal stability up to 800°C. [ABSTRACT FROM AUTHOR]