Selective synthesis of various nanoscale morphologies of hydroxyapatite via an intermediate phase

Hiroyuki Ito, Yuya Oaki, Hiroaki Imai

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76 Citations (Scopus)


Dicalcium phosphate (DCP) was found to be a suitable precursor for nanoscopically controlled hydroxyapatite (HAp) crystals. Nanoscale needles, fibers, and sheets of HAp were selectively prepared through the hydrolysis of a solid precursor crystal of DCP in an alkali solution by varying the pH and ion concentrations. An oriented array of bundled nanoneedles of HAp elongated in the c axis was obtained under a highly basic condition at pH 11-13. The ordered architecture originated from the spatially periodic nucleation of HAp seeds on the DCP surface through topotactic solid-solid transformation. Long HAp fibers were observed under a relatively mild basic condition at pH 9-10. The fibrous morphology evolved from the nanoneedles produced by the solid-solid transformation with the elongation of the c-axis through a dissolution- precipitation route. Flaky HAp nanosheets consisting of a parallel assembly of nanoneedles were observed with an excess amount of phosphate ions under mild basic conditions. The presence of phosphate ions suppressed the solid-solid transformation and promoted the formation of a two-dimensional structure with the dissolution-precipitation process.

Original languageEnglish
Pages (from-to)1055-1059
Number of pages5
JournalCrystal Growth and Design
Issue number3
Publication statusPublished - 2008 Mar

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics


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