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Mechanisms of heterogenous growth of calcium fluorapatite coatings from strongly supersaturated aqueous solutions

Andrey G. Doroshenko ,  Yuriy N. Savin ,  Alexander V. Tolmachev 

Abstract

Fluorapatite (FАp, Са10(P04)6F2) and hydroxyapatite (HAp Са10(P04)6OH2) use as the bioactive coatings of implants [1]. FАp is relevant precursos in production of optical and laser materials, templates of a burial of radioactive materials, mineral fertilizers, is of interest, as idealizing composite and structural mother of marine deposits in the form of marine sedimental apatite [2].

In this study the kinetics and mechanisms of FАp coatings growth and effect of the degree of a supersaturation on a phase composition, structure and morphology of coatings are studied.

Growing of Fap coatings carried on by mixing the aqueous solutions in system CaСl2 – КH2PO4 – NaOH – NaF–NaCl–H2O in a temperature-controlled quartz reactor (200ml) using the constant composition method, at fixed рН=6,5 and temperature 37±0.5 °C.

It is found, that coatings are textured - plains (002), and oriented predominantly parallelly the surfaces of an emulsion carrier. The size of coherent scattering fields of sample studied is 39 nanometers. The calculated radius of an extreme nucleus has compounded 0,9 nanometers. The kinetics of fluorapatite coatings showed, that at supersaturation s < 4, the coatings grow on the dislocation dodge, and when the supersaturation s > 4 - three-dimensional nucleuses mechanizm. It is shown, that at growth on the dislocation dodge, the growth rate is checked by diffusion of ions on surfaces of crystalline nucleuses, and processes of mass transfer do not influence on growth rate.

[1] Eun-Jung Lee, Su-Yeon Chae, and Hyoun-Ee Kim. Improvement in biocompatibility of fluoridated apatite with addition of resorbable glass. J. Am. Ceram. Soc., 89 [5] (2006) 1748–1751

[2] A. Aklil, M. Mouflih, S. Sebti. Removal of heavy metal ions from water by using calcined phosphate as a new adsorbent. Journal of Hazardous Materials. 2004, V. A112, P. 183–190

 

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Related papers

Presentation: Poster at Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth, by Andrey G. Doroshenko
See On-line Journal of Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth

Submitted: 2007-01-15 15:42
Revised:   2009-06-07 00:44