PHYS 367 |
| Hydroxyapatite (HAP), having the chemical formula Ca10(PO4)6(OH)2, is the most stable calcium phosphate at ambient temperatures and pH values between 4 and 12. HAP is of interest not only as a biocompatible material (biomaterial), but also in the areas of heterogeneous catalysis, fertilizers, pharmaceuticals, and water treatment. In the present study, calcium hydroxyl phosphate materials were prepared using an aqueous chloride co-precipitation method (using CaCl2, (NH4)2HPO4, and NH4OH) to synthesize stoichiometric (Ca/P = 1.67) and non-stoichiometric (Ca/Pš 1.67) calcium hydroxyl phosphate as a function of pH and calcination temperature. The Ca/P mole ratio ranged from 1.00 to 1.92. Raman spectroscopy is ideally suited for the study of calcium hydroxyphosphates. The Raman band positions are sensitive to changes in phosphorus-oxygen bond length and the molecular geometry of the phosphate species. These attributes make Raman spectroscopy an effective tool for the detection and identification of both amorphous and crystalline phosphate phases. The results of this study will contribute to understanding the effect of synthesis conditions (Ca/P composition, pH, calcination temperature) on the phases present for stoichiometric and non-stoichiometric compositions. It will also provide a Raman spectral database for the future characterization of thin-film hydroxyapatite on medical-grade titanium substrates to investigate its chemical interaction (adhesion) with titanium implants. |
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PHYS Poster Session - General Experiment
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster
Division of Physical Chemistry |