Reactions of wollastonite and xonotlite with NH4H2PO4and H3PO4
- 1 January 1987
- journal article
- research article
- Published by Walter de Gruyter GmbH in Zeitschrift für Kristallographie
- Vol. 179 (1-4) , 383-393
- https://doi.org/10.1524/zkri.1987.179.1-4.383
Abstract
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 PO43− 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.Keywords
This publication has 3 references indexed in Scilit:
- A novel method for the preparation of extensively dealuminated faujasitesReaction Kinetics, Mechanisms and Catalysis, 1982
- Solubility of Ca5{P04)3OH in the System Ca{OH)2-H3P04-H20 at 5, 15, 25, and 37 °CJournal of Research of the National Bureau of Standards Section A: Physics and Chemistry, 1977
- Solubility and surface properties of finely divided hydroxyapatiteJournal of Research of the National Bureau of Standards Section A: Physics and Chemistry, 1973