Effect of fluoride on apatite formation from Ca4(PO4)2O in 0.1 mol L-1 KH2PO4
Effect of fluoride on apatite formation from Ca4(PO4)2O in 0.1 mol L-1 KH2PO4
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DOI：
10.1023/a:1008850829768
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发表时间：
1998-06-01
影响因子：
3.7
通讯作者：
Chow, LC
中科院分区：
文献类型：
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作者：
Matsuya, S;Matsuya, Y;Chow, LC
研究了在含有0-83 mol l（-1）KF的0.1 mol l（-1）KH_2PO_4溶液中，氟化物对磷酸四钙（TTCP; Ca ~（4+）（PO_4）（2）O）水解的影响。通过X射线衍射和SEM对水解形成的最终磷灰石相进行表征。初始pH在4.5和5.4之间，取决于溶液，并且pH迅速增加并保持恒定在7.3和6.5之间。KF浓度的增加倾向于降低水解最后阶段的pH。在整个反应过程中，钙浓度显著低于磷浓度。在水解开始后不久，氟化物浓度下降。当KF浓度较低时，TTCP在0.1 mol l（-1）KH_2PO_4中水解通过DCPD形成羟基磷灰石。水解产物是Ca/P比约为1.5的缺钙非化学计量羟基磷灰石。在0.1moll（-1）KH_2PO_4溶液中，随着KF浓度的增加，TTCP直接转化为含F ~-离子的羟基磷灰石或氟磷灰石，结晶度提高。在溶液中加入氟化物最初加速了磷灰石的形成。然而，新形成的磷灰石层粘附到TTCP颗粒延迟TTCP溶解，因此，水解被延迟。红外光谱分析表明，磷灰石相的结构中含有HPO 42-离子。TTCP在氟化物存在下的水解产物的分子式可表示为：Ca 10-x（HPO 4）（x）（PO 4）（10-x）（OH）（2-x-y）F-y。
The effect of fluoride on the hydrolysis of tetracalcium phosphate (TTCP; Ca-4(PO4)(2)O) was investigated in 0.1 mol l(-1) KH2PO4 containing 0-83 mol l(-1) KF. Characterization of the final apatite phase formed by the hydrolysis was made with X-ray diffraction and SEM. The initial pH was between 4.5 and 5.4, depending on the solutions, and the pH rapidly increased and was kept constant between 7.3 and 6.5. An increase in KF concentration tended to lower the pH in the final stage of hydrolysis. The calcium concentration was considerably lower than the phosphorus concentration throughout the reaction. The fluoride concentration decreased shortly after the start of hydrolysis. The hydrolysis of TTCP in 0.1 mol l(-1) KH2PO4 proceeded to form hydroxyapatite via DCPD when the KF concentration was low. The hydrolysis product was a calcium-deficient non-stoichiometric hydroxyapatite with a Ca/P ratio of about 1.5. With an increase in the KF concentration in the 0.1 mol l(-1) KH2PO4 solution, TTCP directly transformed into hydroxyapatite containing F- ions or fluorapatite and with improved crystallinity. The addition of fluoride in the solution initially accelerated the formation of apatite. However, the layer of newly formed apatite adhering to the TTCP particles retarded TTCP dissolution; as a result, hydrolysis was delayed. IR analysis showed that the apatite phase contained HPO42- ions in the structure. The formula for the hydrolysis product of TTCP in the presence of fluoride can be expressed as follows: Ca10-x(HPO4)(x)(PO4)(10-x)(OH)(2-x-y)F-y.