The pH Effect on the Growth of Hexagonal and Monoclinic Hydroxyapatite Synthesized by the Hydrothermal Method

Table 2

Corresponding absorption bands (cm^-1) at different pH values.

Group	pH 7	pH 8	pH 9	pH 9.6	pH 10
OH^-, δ bending (cm^-1)	633	633	633	633	633
Free OH^-, unattached (cm^-1)	3572	3572	3572	3572	3572
ν3(PO4)^3- (cm^-1)	1033	1063	1039	1041	1031
ν1(PO4)^3- (cm^-1)	963	963	963	963	963
ν4(PO4)^3- (cm^-1)	565	565	564	567	565