Effect of reaction time on the phase quantity of hydroxyapatite synthesized from Indian clam seashell by hydrothermal technique

Abstract

The hydroxyapatite (HA) powder has been successfully prepared by using calcined Indian clam seashells through the hydrothermal technique. Initially, the clam seashell is calcined at 900 ℃ to achieve calcium oxide (CaO). The obtained seashell-based calcium oxide is mixed properly with pre-determined tri-calcium phosphate in demineralized water. Further, the colloidal solution is heat-treated at a temperature of 1000 ℃ for various time durations (1 h, 1:30 h, 1:45 h, 2 h, 2:30 h, and 3 h) to perform the hydrothermal reactions. Quantification of HA and different phases present in the synthesized powders is carried out with the help of the Rietveld refinement method. The phases, crystallite size, and crystallinity of synthesized powder are evaluated by the X-ray diffraction (XRD) technique. The microstructure of the powder is analyzed through Field Emission Scanning Electron Microscopy (FESEM). The Ca/P ratio and particle size of the prepared powder are estimated by energy-dispersive X-ray spectroscopy (EDS) and the image analysis technique, respectively. The results indicate that the heating duration of the hydrothermal reaction is a crucial parameter in modifying the various properties, specifically the phase quantity of prepared HA. All six synthesized powders show the presence of the HA phase, along with a few secondary phases in those. Spherical and cylindrical nano-crystals of HA are observed to form. With an increase in time duration, coarsening of crystallite is observed. The average particle size and crystallinity of HA are also noticed to be increased with increased time duration. © 2023, The Author(s) under exclusive licence to Australian Ceramic Society.