Structure and stability of hydroxyapatite: Density functional calculation and Rietveld analysis

Donncha Haverty, Syed A. M. Tofail, Kenneth T. Stanton, and James B. McMonagle
Phys. Rev. B 71, 094103 – Published 7 March 2005

Abstract

A study on the structure and energetics of hydroxyapatite has been carried out using generalized gradient approximation density functional theory. The previously proposed P63m and P63 hexagonal structural models have been found to be energetically unfavorable as compared with the previously proposed P21b symmetry and a newly proposed monoclinic P21 structural model. A detailed analysis of the symmetry restrictions and inconsistencies between the reported physical properties, such as diffraction and birefringence, with hexagonal symmetry question the validity of these models. Rietveld analysis carried out on a synthetic sample, reported to be predominantly hexagonal at room temperature, shows that the diffraction pattern of this material can be interpreted as a mixed monoclinic phase, 23% monoclinic P21b and 77% monoclinic P21. This interpretation reconciles many anomalies in reported experimental observations.

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  • Received 23 August 2004

DOI:https://doi.org/10.1103/PhysRevB.71.094103

©2005 American Physical Society

Authors & Affiliations

Donncha Haverty*, Syed A. M. Tofail, Kenneth T. Stanton, and James B. McMonagle§

  • Materials and Surface Science Institute, University of Limerick, National Technological Park, Limerick, Ireland

  • *Electronic address: donncha.haverty@ul.ie
  • Electronic address: tofail.syed@ul.ie
  • Electronic address: kenneth.stanton@ul.ie; Also at: Department of Mechanical Engineering, University College Dublin, Belfield, Dublin 4, Ireland.
  • §Electronic address: seamus.mcmonagle@ul.ie

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Issue

Vol. 71, Iss. 9 — 1 March 2005

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