



@article {2556,
	title = {Structural insights of glass-reinforced hydroxyapatite composites by Rietveld refinement},
	journal = {BiomaterialsBiomaterials},
	volume = {21},
	year = {2000},
	note = {Cited By (since 1996): 14Export Date: 21 November 2012Source: ScopusCODEN: BIMADdoi: 10.1016/S0142-9612(00)00068-5PubMed ID: 10919694Language of Original Document: EnglishCorrespondence Address: Santos, J.D.; Instituto Engenharia Biomedica, Laboratorio de Biomateriais, Rua do Campo Alegre 823, 4150-180 Porto, Portugal; email: jdsantos@alf.fe.up.ptChemicals/CAS: beta-tricalcium phosphate; Biocompatible Materials; Calcium Phosphates; Hydroxyapatites; Magnesium, 7439-95-4; Trace Elements; tricalcium phosphate, 7758-87-4References: Elliot, J.C., Structure and chemistry of the apatites and other calcium orthophosphates (1994) Studies in Inorganic Chemistry, 18. , Amsterdam: Elsevier Science;Okazaki, M., Sato, M., Computer graphics of hydroxyapatite and β -tricalcium phosphate (1990) Biomaterials, 11, pp. 573-578; 
Hench, L.L., Wilson, J., An introduction to bioceramics (1993) Advanced Series in Ceramics, 1, pp. 139-180. , editors. Singapore: World Scientific; 
Santos, J.D., Knowles, J.C., Reis, R.L., Monteiro, F.J., Hastings, G.W., Microstructural characterisation of glass-reinforced hydroxyapatite composites (1994) Biomaterials, 15 (1), pp. 5-10; 
Lopes, M.A., Santos, J.D., Monteiro, F.J., Knowles, J.C., Glass-reinforced hydroxyapatite: A comprehensive study of the effect of glass composition on the crystallography of the composite (1998) J Biomed Mater Res, 39 (2), pp. 244-251; 
Lopes, M.A., Santos, J.D., Monteiro, F.J., Serro, A.P., Saramago, B., Hydrophobicity, surface tension, and zeta potential of glass-reinforced hydroxyapatite composites (1999) J Biomed Mater Res, 45, pp. 370-375; 
Lopes, M.A., Knowles, J.C., Kuru, L., Santos, J.D., Monteiro, F.J., Olsen, I., Flow cytometry for assessing biocompatibility (1998) J Biomed Mater Res, 41, pp. 649-656; 
Li, P., (1993) In Vitro and in Vivo Calcium Phosphate Induction on Gel Oxides, , PhD thesis, Leiden, Offsetdrukkerij Haveka B.V. ed; 
Hagen, A.R., Structural features of biologically involved phosphates (1970) Acta Odontol Scand, 58, pp. 149-173; 
Narasaraju, T.S.B., Phebe, D.E., Review: Some physicochemical aspects of hydroxylapatite (1996) J Mater Sci, 31, pp. 1-21; 
Kay, M.I., Young, R.A., Posner, A.S., The crystal structure of hydroxyapatite (1964) Nature, 204, pp. 1050-1052; 
Montel, G., Bonel, G., Heughebaert, J.C., Trombe, J.C., Rey, C., New concepts in the composition, crystallisation and growth of the mineral component of calcified tissues (1981) J Crystal Growth, 53, pp. 74-99; 
Fanovich, M.A., Castro, M.S., Porto L{\'o}pez, J.M., Analysis of the microstructural evolution in hydroxyapatite ceramics by electrical characterisation (1999) Ceramics Int, 25, pp. 517-522; 
Bigi, A., Falini, G., Foresti, E., Gazzano, M., Ripamonti, A., Roveri, N., Rietveld structure refinements of calcium hydroxyapatite containing magnesium (1996) Acta Crystallogr, 52, pp. 87-92; 
Okazaki, M., Sato, M., Takahashi, J., Space-cutting model of hydroxyapatite (1995) Biomaterials, 16, pp. 45-49; 
Ravalgloli, A., Krajewski, A., (1992) Bioceramics, pp. 16-59. , London: Chapman \& Hall; 
Okazaki, M., Takahashi, J., Kimura, H., Unstable behavior of magnesium-containing hydroxyapatites (1986) Caries Res, 20, pp. 324-331; 
Kotani, S., Fijita, Y., Kitsugi, T., Nakamura, T., Yamamuro, T., Ohtsuki, C., Kokubo, T., Bone bonding mechanism of β -tricalcium phosphate (1991) J Biomed Mater Res, 25, pp. 1303-1315; 
Eanes, E.D., Thermochemical studies on amorphous calcium phosphate (1970) Calcif Tiss Res, 5, pp. 133-145; 
De Groot, K., Klien, P.A.T., Wolke, J.G.C., De Blieck-Hogervorst, J.M.A., Chemistry of calcium phosphate bioceramics (1990) Handbook of Bioactive Ceramics, 2, pp. 3-16. , T. Yamamuro, L.L. Hench, Wilson J. Boca Raton, FL: CRC Press; 
Legeros, R.Z., Calcium phosphates in oral biology and medicine (1991) Monographs in Oral Science, 15, pp. 87-107. , New York: Karger
},
	month = {2000///},
	pages = {1905 - 1910},
	publisher = {Elsevier Science Ltd},
	abstract = {Phase transformations and interstitial and/or substitution of trace elements during the liquid-phase sintering process of P                        2O
                        5-CaO-MgO glass-reinforced hydroxyapatite (GR-HA) composites were examined by X-ray diffraction and Rietveld analyses. Using the Rietveld method for structure refinement, changes in the lattice parameters of the two main phases of the composites, hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), as well as changes in several bond lengths and in the occupancy of the hydroxyl oxygen site in the HA phase structure were assessed. The glasses gave rise to formation of between approximately 45 and 50\% of β-TCP, with evidence for the Mg
                        2+ enhancing the formation of β-TCP. Between 1300 and 1350{\textdegree}C, the β-TCP inverts to α-TCP, without further decomposition of the residual HA. The glasses showed evidence for stabilisation of the hydroxyl group located in the hydroxyl channels. This is supported by measurements of the hydroxyl channel radius (R(c)), the Ca
                        2-OH bond length and the hydroxyl oxygen occupancy (O(occ)). Results showed that the Mg
                        2+ containing glasses induced the β-TCP phase formation in the structure of GR-HA composites and retarded the β-TCP into α-TCP transformation at higher temperatures. The chemical composition of the P
                        2O
                        5 glasses also induces modifications in the lattice parameters of the crystallographic phases present in the microstructure of the composites. This suggests some substitution of Mg
                        2+-for-Ca
                        2+ in the β-TCP structure during the liquid-phase sintering process. Copyright (C) 2000 Elsevier Science Ltd.
Phase transformations and interstitial and/or substitution of trace elements during the liquid-phase sintering process of P
                        2O
                        5-CaO-MgO glass-reinforced hydroxyapatite (GR-HA) composites were examined by X-ray diffraction and Rietveld analyses. Using the Rietveld method for structure refinement, changes in the lattice parameters of the two main phases of the composites, hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), as well as changes in several bond lengths and in the occupancy of the hydroxyl oxygen site in the HA phase structure were assessed. The glasses gave rise to formation of between approximately 45 and 50\% of β-TCP, with evidence for the Mg
                        2+ enhancing the formation of β-TCP. Between 1300 and 1350 {\textdegree}C, the β-TCP inverts to α-TCP, without further decomposition of the residual HA. The glasses showed evidence for stabilization of the hydroxyl group located in the hydroxyl channels. This is supported by measurements of the hydroxyl channel radius (R
                        c), the Ca
                        2-OH bond length and the hydroxyl oxygen occupancy (O
                        occ). Results showed that the Mg
                        2+ containing glasses induced the β-TCP phase formation in the structure of GR-HA composites and retarded the β-TCP into α-TCP transformation at higher temperatures. The chemical composition of the P
                        2O
                        5 glasses also induces modifications in the lattice parameters of the crystallographic phases present in the microstructure of the composites. This suggests some substitution of Mg
                        2+-for-Ca
                        2+ in the β-TCP structure during the liquid-phase sintering process.
},
	keywords = {article, Biocompatible Materials, Biomedical engineering, Calcium Compounds, calcium phosphate, Calcium phosphates, Chemical bonds, chemical composition, Composition effects, Crystal lattices, Crystal microstructure, crystal structure, Crystallization, decomposition, Fiber reinforced materials, glass, Glass fibers, Glass-reinforced hydroxyapatite, Glass-reinforced hydroxyapatite composites, hydroxyapatite, Hydroxyapatites, Implants (surgical), Liquid-phase sintering, Magnesium, Mg-apatites, Models, Molecular, phase transition, Phase transitions, Phosphate minerals, priority journal, Rietveld refinement, Rietveld refinement analysis, Sintering, spectacles, structure analysis, temperature, Thermodynamics, Trace Elements, Tricalcium phosphate, X ray analysis, X ray crystallography, β-TCP},
	isbn = {01429612 (ISSN)},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0034046953\&partnerID=40\&md5=45db5eace3328b0cb2a8a048985ba619},
	author = {Lopes, M.A. and Knowles, J.C. and Santos, J.D.}
}
