Reactions of wollastonite and xonotlite with NH4H2PO4 and H3PO4

Michihiro Miyake, Sridhar Komarneni, Rustum Roy

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4 Scopus citations


The reactions of wollastonite, CaSiO3 and xonotlite,Ca6Si6O17(OH)2 with NH4H2PO4 and H3PO4 have been investigated to determine whether silicophosphates can be synthesized topotactically. Hydroxyapatites were easily obtained from the reaction of the phosphate sources with xonotlite and wollastonite. The crystallinity of the hydroxyapatites increased with a decrease in the concentration of NH4H2PO4 and H3PO4 solution and an increase in temperature. Scanning electron microscopy showed that the morphology of the hydroxyapatite obtained was different from those of wollastonite and xonotlite. The chain structures of the SiO4 tetrahedra in wollastonite and xonotlite, however, were broken down by the attack of the PO4“ ions, and products such as hydroxyapatite, brushite and orthophosphate were produced. Hydroxyapatite was found to be the stable product above pH ~ 4.0 when xonotlite and wollastonite reacted with the above phosphate sources. The low-temperature transformation of calcium silicates to hydroxyapatites may find applications in the production of prosthetic implants.

Original languageEnglish (US)
Pages (from-to)383-393
Number of pages11
JournalZeitschrift fur Kristallographie - New Crystal Structures
Issue number1-4
StatePublished - 1987

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics
  • Inorganic Chemistry


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