Effects of pH and Ca/P molar ratio on the quantity and crystalline structure of calcium phosphates obtained from aqueous solutionsEffets du pH et du ratio molaire Ca/P sur la quantité et la structure cristalline des phosphates de calcium obtenus à partir de solutions aqueuses.

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Table III.

Characteristics of the suspensions and precipitates of calcium phosphates obtained at constant pH. Precipitate analyses performed using XRD and FTIR. CDA. (Crystalline * ** *** amorphous).

Initial conditions		Terminal conditions						Precipitate characterization
pH	Ca/P	pH	Precipitated calcium		Precipitated phosphate		Ca/P	XRD	FTIR
			mmol·L⁻¹	% total	mmol·L⁻¹	% total
6.70	1.00	6.70	19.18	95.90	11.93	59.65	1.61	CDA*	CDA
6.70	1.50	6.70	27.81	92.70	18.43	92.15	1.51	CDA*	CDA
6.70	2.00	6.70	29.96	74.90	19.78	98.90	1.51	CDA*	CDA
7.50	1.00	7.50	19.76	98.80	13.89	69.45	1.42	CDA*	CDA
7.50	1.50	7.50	28.60	95.33	19.68	98.40	1.45	CDA*	CDA
7.50	2.00	7.50	29.20	73.00	19.95	99.75	1.46	CDA*	CDA
8.50	1.00	8.50	19.94	99.70	13.69	68.45	1.46	CDA**	CDA
8.50	1.50	8.50	28.50	95.00	19.64	98.20	1.45	CDA**	CDA
8.50	2.00	8.50	28.54	71.35	19.95	99.75	1.43	CDA**	CDA
9.50	1.00	9.50	19.92	99.96	13.47	67.35	1.48	CDA***	CDA
9.50	1.50	9.50	29.22	97.40	19.85	99.25	1.47	CDA***	CDA
9.50	2.00	9.50	28.96	72.40	19.99	99.95	1.45	CDA***	CDA