Synthesis of Novel High Silicate-Substituted Hydroxyapatite by Co-Substitution Mechanisms

Jennifer A. Stephen, Jan Skakle, Iain Ronald Gibson

Research output: Chapter in Book/Report/Conference proceedingChapter

12 Citations (Scopus)


Silicate substituted hydroxyapatite bioceramics have been shown to enhance bone repair in vivo compared to hydroxyapatite (HA), although the amount of silicate ions that can be substituted alone into the hydroxyapatite structure is limited to approximately 5.2 wt%, or 1.6 wt% Si. This study describes the substitution of greater levels of silicate ions via co-substitution of silicate ions with trivalent yttrium ions, without resulting in the formation of any secondary phases. This substitution mechanism involves a coupled Substitution of yttrium and silicate ions for calcium and phosphate ions, respectively, and enables a level of silicate substitution up to approximately 9 wt%. Two different substitution mechanisms result in subtle differences in the crystal structure. When the mechanism xY(3+) + XSiO44- was used, a small decrease in the a-axis, but no change in the c-axis, of the unit cell compared to HA was observed. In contrast, when the mechanism x/2 Y3+ + XSiO44- was used, a significant increase in the c-axis of the unit cell was observed, compared to HA. XRF analysis and FTIR spectroscopy Supported the proposed substitution mechanisms. These novel substitution mechanisms not only enable greater levels of'siticate-substitution in HA to be prepared, but also allow the production of compositions with the same level of silicate substitution, and with subtle differences in chernical structure.

Original languageEnglish
Title of host publicationBioceramics
EditorsXingdong Zhang, Xudong Li, Hongsong Fan, Xuanyong Liu
Place of PublicationZurich, Switzerland
PublisherTrans Tech Publications Ltd
Number of pages4
ISBN (Print)0878494227, 978-0878494224
Publication statusPublished - 1 Feb 2007
Event19th International Symposium on Ceramics in Medicine - Chengdu, China
Duration: 10 Oct 200613 Oct 2006

Publication series

NameKey Engineering Materials
PublisherTrans Tech Publications Ltd
ISSN (Print)1013-9826


Conference19th International Symposium on Ceramics in Medicine


  • hydroxyapatite (ha)
  • silicate
  • co-substitution
  • X-ray diffraction
  • silicon
  • granules


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