. Calcified tissues; proceedings. Bone; Collagen; Calcification. Physico-chemical Methods for the Identification of Microcristalline Basic Calcium 135 specific area of the intermediary product is 130±10m-/g according to the electron micrograph. The suspension of the amorphous product in water leads to crystalline material of hydroxyapatite X-ray diffraction patterns with the same pH-curve as the HA. The Ca/P ratio of the amor- phous product is the same as the one for its water suspension at any time and pH, and also the same as that for the end product of the uninterrupted Hayek synthesis. TG-
. Calcified tissues; proceedings. Bone; Collagen; Calcification. Physico-chemical Methods for the Identification of Microcristalline Basic Calcium 135 specific area of the intermediary product is 130±10m-/g according to the electron micrograph. The suspension of the amorphous product in water leads to crystalline material of hydroxyapatite X-ray diffraction patterns with the same pH-curve as the HA. The Ca/P ratio of the amor- phous product is the same as the one for its water suspension at any time and pH, and also the same as that for the end product of the uninterrupted Hayek synthesis. TG- and DTA-curves of the a- morphous product are very dif- ferent to those of HA (Fig. 3). The characteristic temperatures are now 100''C, 170'-'C and 300'-'C, re- presenting waterlosses of about 8 moles (adsorbed water), and — moles. The total waterloss up to 1000 °C is to moles. The DTA-curve corresponds with the TG-curve except for one exo- thermic peak at 680 C. These curves resemble those of a mixture of TCPH and OCP, which are shown in Fig. 4. X-ray analysis shows that the product re- mains amorphous up to 600 °C. At 650 '^C the reflexes of the r/-TCP appear thus corresponding to the exothermic peak of the DTA. At 650 C we can observe the X-ray pattern of /j-TCP. Therefore, we c can state that the amorphous pro- duct is a mixture of TCPH and OCP. If we consider the pH of : the intermediary step as the end- pH, we find according to equation (1) a Ca/P ratio about The discrepancy in the experimental value can be explained by surface adsorption of Ca'-*. This shows us that global chemical analyses are unsufficient to determine the real nature of hydroxyapatites. In aqueous suspension the amorphous product is hydrolized and the pH 400 600 800 °C :urves of amorphous product. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illus
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