Effect of temperature on crystallinity of carbonate apatite foam prepared from α-tricalcium phosphate by hydrothermal treatment

The effect of temperature on crystallinity of carbonate apatite (CAp) foam prepared from α-tricalcium phosphate (α-TCP) foam by hydrothermal treatment was investigated in the present study. The α-TCP foams were prepared through a conventional sintering method using polyurethane foam as template. Then, the resultant α-TCP foams were hydrothermally treated with Na2CO3 aqueous solution at 100 ◦ C, 150 ◦ C and 200 ◦ C for 72 h. After hydrothermal treatment, the cancellous bone-like macroporous structure of the α-TCP foams was maintained. However, microscopic morphology of the foams' frame significantly changed after the 72 h treatment period. The smooth surface of α-TCP foam disappeared and the whole surface was covered with plate-like deposits. The plate-like deposits treated at 150 ◦ C and 200 ◦ C had smooth surface while those treated at 100 ◦ C were constructed from spherical particles of approximately 200 nm in diameter. The results of X-ray diffraction and Fourier transform infrared analysis showed that α-TCP was completely converted to CAp and the crystallinity of CAp prepared at 100 ◦ C was significantly lower than those prepared at 150 ◦ C and 200 ◦ C. Hydrothermal treatment of α-TCP foam at 100 ◦ C