Physics and Chemistry of Minerals

, Volume 38, Issue 2, pp 111–122

Line-broadening effects in the powder infrared spectrum of apatite

  • Etienne Balan
  • Simon Delattre
  • Damien Roche
  • Loïc Segalen
  • Guillaume Morin
  • Maxime Guillaumet
  • Marc Blanchard
  • Michele Lazzeri
  • Christian Brouder
  • Ekhard K. H. Salje
Original Paper

DOI: 10.1007/s00269-010-0388-x

Cite this article as:
Balan, E., Delattre, S., Roche, D. et al. Phys Chem Minerals (2011) 38: 111. doi:10.1007/s00269-010-0388-x

Abstract

The crystallinity of natural and synthetic apatite samples is often determined from the broadening of ν4 PO4 infrared absorption bands. However, various physical mechanisms contribute to the observed linewidth. In the present study, the factors determining the linewidth in the powder spectrum of synthetic fluorapatite and hydroxyapatite samples are investigated. The temperature dependence of the infrared spectrum (10–270 K) is used to assess the respective contributions of homogeneous broadening, related to the decay of phonons through anharmonic coupling, and heterogeneous broadening related to elastic strain and macroscopic electrostatic effects. This latter contribution is dominant in the investigated samples and depends on the shape of powder particles. It is discussed under the light of the theoretical modeling of the low-frequency dielectric properties of apatite based on first-principles density functional theory calculations. The linewidth of the weak ν1 PO4 absorption band provides a reliable information on microscopic sources of broadening, i.e., apatite crystallinity. In comparison, the other more intense PO4 bands are more sensitive to long-range electrostatic effects.

Keywords

Apatite Infrared spectroscopy First-principles calculations Anharmonicity 

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Etienne Balan
    • 1
  • Simon Delattre
    • 1
  • Damien Roche
    • 2
  • Loïc Segalen
    • 2
  • Guillaume Morin
    • 1
  • Maxime Guillaumet
    • 1
  • Marc Blanchard
    • 1
  • Michele Lazzeri
    • 1
  • Christian Brouder
    • 1
  • Ekhard K. H. Salje
    • 3
  1. 1.Institut de Minéralogie et Physique des Milieux Condensés (IMPMC), UMR CNRS 7590, UMR IRD 206Université Paris VI, Université Paris VII, IPGPParisFrance
  2. 2.UPMC Univ Paris 06, UMR 7193 ISTEP, Biominéralisations et Environnements SédimentairesParisFrance
  3. 3.Department of Earth SciencesUniversity of CambridgeCambridgeUK