Maximising carbonate content in sodium-carbonate Co-substituted hydroxyapatites prepared by aqueous precipitation reaction

Duncan A. Nowicki, Janet M. S. Skakle, Iain. R. Gibson

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4 Citations (Scopus)


We report the synthesis of a range of sodium-carbonate co-substituted hydroxyapatite compositions with sodium and measured carbonate contents ranging from approximately 0.4-0.8 wt% and 4.4-14.2 wt%, respectively, via aqueous precipitation reaction between calcium hydroxide, phosphoric acid and either sodium carbonate or sodium hydrogen-carbonate. A subsequent heat treatment in dry CO2 at 600°C allowed for a Na-CO3 co-substituted apatite containing approximately 17.7 wt% carbonate to be prepared, one of the largest carbonate contents reported to date for such a material. Deconvolution of FTIR data showed that the incorporated carbonate ions were situated on both hydroxyl and phosphate sites. Increasing the heat treatment in dry CO2 from 300 up to 600°C, prior to the decomposition point of these compositions, showed a trend towards an increase in the distribution of carbonate on the main B-site at the expense of a decrease on the main A-site, although overall the total carbonate content increased with increasing temperature. Changes in the a lattice parameter with increasing carbonate content dominated, with a marked decrease in the a parameter with increasing addition of sodium carbonate, and an increase when samples were further heated in dry CO2. These results demonstrate that highly carbonated sodium-carbonate co-substituted hydroxyapatites can be obtained using a simple, room temperature, aqueous precipitation reaction with starting reagents unlikely to pose significant environmental risks, adding a further degree of flexibility to the preparation of these materials and an increase in the scope of their application to fields beyond biomaterials.
Original languageEnglish
Article number122042
JournalJournal of Solid State Chemistry
Early online date15 Feb 2021
Publication statusPublished - May 2021


  • Hydroxyapatite
  • Sodium
  • Carbonate
  • Percipitation
  • Biomaterials


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