Phase formation and evolution in the silicon substituted tricalcium phosphate/apatite system
| Autor: | Timothy J. N. Smith, M. Sayer, Joel Reid, Derek Dunfield, A. Pietak |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Calcium Phosphates
Ceramics Time Factors Materials science Silicon Biophysics Nucleation Sintering chemistry.chemical_element Mineralogy Biocompatible Materials Bioengineering Calcium Apatite Biomaterials Colloid X-Ray Diffraction Apatites Lattice (order) Materials Testing Doping Temperature Silicon Dioxide Kinetics Durapatite Models Chemical chemistry Chemical engineering Mechanics of Materials visual_art Ceramics and Composites visual_art.visual_art_medium Thermodynamics Hydroxyapatites |
| Zdroj: | Biomaterials. 26:2887-2897 |
| ISSN: | 0142-9612 |
| DOI: | 10.1016/j.biomaterials.2004.09.005 |
| Popis: | The sintering of silicon doped calcium phosphate ceramics prepared from a basic colloidal hydroxyapatite (Ca5(PO4)3OH or HA) precipitate mixed with silica over 800 degrees C yields a phase mixture of tricalcium phosphate phases (TCP) designated Si-TCP, beta-TCP and a silicon substituted dehydrated apatite (Si-Ap). The Si-TCP phase is defined as a combination of a silicon stabilized TCP in which the silicon content attains a saturated value (Ca3(P0.9Si0.1O3.95)2 or Si-TCP(sat)) and alpha-TCP (Ca3(PO4)2). Si-TCP(sat) has the same crystalline space group (P2(1)/a) as alpha-TCP, but with characteristically different lattice parameters due to the substitution of silicon in tetrahedral phosphorus sites. The nucleation and growth kinetics of Si-TCP in samples of composition 0.2 mol SiO2:mol HA (0.2:1) and 1 mol SiO2:mol HA (1:1) can be understood in terms of the initial growth of alpha-TCP at a silica-HA interface followed by a transformation to Si-TCP(sat) or beta-TCP. A thermodynamic model for the formation of Si-TCP(sat) predicts a nucleation temperature of 795 degrees C, in close agreement with experiment. If sufficient silicon is available, the alpha-TCP transforms to Si-TCP(sat) during extended sintering. In the absence of sufficient silicon, the alpha-TCP transforms to beta-TCP. |
| Databáze: | OpenAIRE |
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