Substitution Structure, Phase Tranversion and Absorbing F- Action of the CHAP in Nanoscale

The nano carbonate-containing hydroxyapatite(CHAP) with different CO32- contents (WC032-) was prepared by a sol-gel process. DTA, TG, XRD, FTIR, TEM,dynamic absorption test and crystalline density measurement were used to study substitution structure, phase tranversion and absorbing F- action of the CHAP. Test results indicate that the CHAP is with AB mixed-type substitution structure. When WCO32- 3.34%, RI increases and capacities absorbing F- decrease with the increasing of CO32- contents, and the CHAP has preferentially a tendency of absorbing CO32- to enter its lattice in absorbing F- process, and a phase tranversion from the CHAP to Ca-deficient HAP takes place at 150～776℃, then the HAP occurs dehydroxy phase tranversion at 776℃. When WCO32-=3.34%, RI has maximum value, a phase tranversion from the CHAP to Ca-stoichiometric HAP takes place at 150～776℃, so the dehydroxy phase tranversion of HAP can not occur at 776℃. When 3.34% WCO32-7.52%, RI decreases and capacities absorbing F- increase with the increasing of CO32- content, and the CHAP has preferentially a tendency of absorbing F- to enter its lattice and exchanging out CO32- in absorbing F- process, and a phase tranversion from the CHAP to Ca-surplus HAP takes place at 150～776℃, so the dehydroxy phase tranversion of HAP can not occur at 776℃. The nano CHAP crystals have a behavior of dissolving along crystal length, and 2～3 times capacities absorbing F- of the pure HAP, and show an effect of dissolving-precipitating adsorption in nanoscale.