Structural insights of glass-reinforced hydroxyapatite composites by Rietveld refinement

• Type: Article in International Scientific Journal
• Date: 2000

Authors

Maria Ascensão Lopes (Author) FEUP; J. C. Knowles (Author) Other; José Domingos Santos (Author) FEUP

Journal

Title: Biomaterials

Vol. 21 No. 18

Pages: 1905-1910

ISSN: 0142-9612

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 23 Citations

ISI Web of Science

Scopus - 26 Citations

COMPENDEX

Scientific classification

FOS: Engineering and technology > Environmental biotechnology

Other information

Authenticus ID: P-000-Z0Z

DOI: 10.1016/s0142-9612(00)00068-5

Abstract (EN): Phase transformations and interstitial and/or substitution of trace elements during the liquid-phase sintering process of P(2)O(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 beta-tricalcium phosphate (beta-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 beta-TCP, with evidence for the Mg(2+) enhancing the formation of beta-TCP. Between 1300 and 1350 degrees C, the beta-TCP inverts to alpha-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 (0(occ)). Results showed that the Mg(2+) containing glasses induced the beta-TCP phase formation in the structure of GR-HA composites and retarded the beta-TCP into alpha-TCP transformation at higher temperatures. The chemical composition of the P(2)O(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 beta-TCP structure during the liquid-phase sintering process.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6