Monoclinic ↔ hexagonal phase transition in hydroxyapatite studied by X-ray powder diffraction and differential scanning calorimeter techniques

Hiroyuki Suda, Masatomo Yashima, Masato Kakihana, Masahiro Yoshimura

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74 Citations (Scopus)

Abstract

We investigated the transition between the monoclinic (P21/b) and hexagonal (P63/m) phases of hydroxyapatite, Ca5(PO4)3OH, both by X-ray diffraction (XRD) and differential scanning calorimeter (DSC) techniques. Peak intensities of XRD of the low-temperature monoclinic phase were almost unchanged up to 473 K but dropped abruptly to zero above 483 K. Endo- and exothermic DSC peaks and a specific heat anomaly associated with the transition were observed. The transition enthalpy and entropy were estimated to be 630 ± 25 J/mol and 1.30 ± 0.05 J/mol·K, respectively.

Original languageEnglish
Pages (from-to)6752-6754
Number of pages3
JournalJournal of Physical Chemistry
Volume99
Issue number17
Publication statusPublished - 1995 Dec 1

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Physical and Theoretical Chemistry

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