An Analysis of Hydroxyapatite Surface Layer Formation
| Autor: | Roger I. Martin, Paul W. Brown |
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| Rok vydání: | 1999 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry B. 103:1671-1675 |
| ISSN: | 1520-5207 1520-6106 |
| DOI: | 10.1021/jp982554i |
| Popis: | A mechanism for the formation of hydroxyapatite (HAp) surface layers compositionally different from the bulk compositions is described. Surface layer formation is a consequence of HAp being a compound of variable composition: Ca10(PO4)6(OH)2 to ∼Ca9HPO4(PO4)5OH, existing over Ca/P ratio from 1.67 for stoichiometric to ∼1.5 for fully calcium-deficient HAp. One consequence of this compositional variability is that only one HAp composition (Ca/P ratio) dissolves congruently (the solution and solid have the same Ca/P ratio). HAp compositions having Ca/P ratios different from the congruently dissolving composition will form surface layers. Equilibration of stoichiometric HAp with water will result in the formation of a surface layer having a Ca/P ratio of less than 1.67. In general, for solid HAp compositions having Ca/P ratios greater than that of the congruently dissolving composition, a nonstoichiometric surface layer will form and the Ca/P ratio in solution will exceed that of the surface layer. For solid... |
| Databáze: | OpenAIRE |
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