Comparison of Carbonate Hydroxyapatite with and without Sodium Co-Substitution

Jennifer A. Stephen, C. Pace, Jan Skakle, Iain Ronald Gibson

Research output: Chapter in Book/Report/Conference proceedingChapter

10 Citations (Scopus)


Carbonate hydroxyapatite (CHA) bioceramics can be synthesised to contain sodium ions as a co-substituted ion, or as sodium-free compositions. it is unclear, however, which composition would produce the optimum biological response. The aim of this study was to find a reliable method to produce sodium co-substituted and sodium-free CHA compositions that would have the same level of carbonate substitution, and to characterise the effects of the two different substitutions on the structure of the CHA samples. After sintering at 900 degrees C in a CO2 atmosphere, ail samples contained approximately equal amounts of carbonate groups on the A- and B-sites, as observed by FTIR. The sample produced with NaHCO3 and the sodium-free sample (CHA1) have comparable carbonate contents, whereas the sample produced with Na2CO3 contains significantly more carbonate, probably due to the excess sodium ions allowing more carbonate co-substitution. The sodium-free CHA sample, however, has significantly smaller unit cell parameters compared to both sodium co-substituted CHA samples, and also to HA. This characterisation of the samples shows that the sodium-free CHA sample (CHA1) and the sample produced with NaHCO3 would provide CHA compositions for biological testing with similar carbonate contents and distributions, but with structural differences due to the sodium substitution.

Original languageEnglish
Title of host publicationBioceramics
EditorsGuy Daculsi, Pierre Layrolle
Place of PublicationZurich, Switzerland
PublisherTrans Tech Publications Ltd
Number of pages4
ISBN (Print)0878494227, 9780878494224
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
  • carbonate
  • co-substitution
  • sodium
  • X-ray diffraction


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