Hydroxyapatite formation from calcium carbonate single crystal under hydrothermal condition: Effects of processing temperature

Hydrothermal processing has been used for synthesis of hydroxyapatite (HAp) crystals with unique morphologies. Our previous studies reported that the morphology of HAp was affected by dissolution behavior of starting materials under a hydrothermal condition. In this study we evaluated the effects of processing temperature on formation and morphology of HAp crystals under a hydrothermal condition. Calcite (CaCO3) single crystal as a starting material was hydrothermally treated in a phosphate solution at various temperatures. After hydrothermal processing for 24 h, needle-shaped HAp crystals formed on the surfaces of all the samples. The size of HAp crystals increased with increasing the processing temperature. Plate-shaped HAp was observed on the cross-section of the starting material treated at 200 degrees C. The structure of HAp plates were generated by arrangement of needle-shaped HAp crystals during their crystal growth. The difference in the processing temperature affects the morphology and structure of HAp formed on the starting material under the hydrothermal condition. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.