Abstract
The effect of methanol on the morphology of hydroxyapatite (HAp) crystals has been studied under hydrothermal conditions. A precursor HAp slurry prepared from CaCO3 and CaHPO4⋅2H2O was synthesized hydrothermally in the presence of methanol. The products obtained from slurries containing varying amounts of methanol were found to be carbonate-containing HAp by X-ray diffraction and IR spectrometry. TEM showed that the morphology of the products was influenced by the amount of methanol added to the slurry. The products obtained from slurries without methanol were rod-like or granular crystals, about 20 to 100nm in size. Addition of methanol to the slurries caused an increase in the ratio of plate-like crystals to rod-like crystals or granular crystals. When the weight of methanol added was equal to the weight of the slurry, only plate-like crystals 20 to 200nm in size were obtained. X-ray diffraction patterns of oriented products indicated that the plane grown selectively was the a-plane of the plate-like crystals. The results by DTA suggested that the variation of the morphology can be attributed to the adsorption of methanol on the surface of the HAp nuclei inhibiting the crystal growth along a particular axis.
