The Library
Time and position resolved in situ X-ray diffraction study of the hydrothermal conversion of gypsum monoliths to hydroxyapatite
Tools
Tools
Tools
Fisher, Robin D. and Walton, Richard I. (2009) Time and position resolved in situ X-ray diffraction study of the hydrothermal conversion of gypsum monoliths to hydroxyapatite. Dalton Transactions (No.38). pp. 8079-8086. doi:10.1039/b910485m
Research output not available from this repository, contact author.
Official URL: http://dx.doi.org/10.1039/b910485m
Abstract
Time-resolved energy dispersive X-ray diffraction (EDXRD) data have been measured in situ from cast blocks of gypsum, CaSO4 center dot 2H(2)O, in the presence of reactive phosphate solutions under hydrothermal conditions (100 <= T <= 180 degrees C) in order to understand the formation of hydroxyapatite monoliths, for applications such as in artificial bone or dental materials. Measurement of data in short (60 s) intervals has thus permitted information about the kinetics and mechanism of transformation of gypsum to hydroxyapatite to be obtained in a non-invasive way, avoiding the irreversible conversion of hydrous intermediate phases that would occur on quenching. At the lower temperatures used gypsum first converts to an amorphous intermediate phase during reaction, but as the temperature is raised to 130 degrees C and above, hydrothermal dehydration to the subhydrate CaSO4 center dot 1/2H(2)O always occurs before hydroxyapatite crystallises. The final crystal size of the hydroxyapatite is estimated from the peak broadening of the EDXRD data and this reveals an increase in crystal dimension with increasing reaction temperature. Comparing measurements from the surface and from the core of the blocks shows that an additional phosphate phase, CaHPO4, is observed in the core at two temperatures and also that the crystal growth of hydroxyapatite does not penetrate the core of the block on the time scales we have investigated (up to 6 hours). The observations have important implications in the fabrication of hydroxyapatite monoliths from cast gypsum for applications, since the conversion via several intermediate phases may compromise the integrity and mechanical properties of the monoliths.
| Item Type: | Journal Article | ||||
|---|---|---|---|---|---|
| Subjects: | Q Science > QD Chemistry | ||||
| Divisions: | Faculty of Science > Chemistry | ||||
| Library of Congress Subject Headings (LCSH): | Hydroxyapatite, Gypsum, Crystallization, X-rays -- Diffraction, Calcium sulfate, Crystals -- Structure, Hydration | ||||
| Journal or Publication Title: | Dalton Transactions | ||||
| Publisher: | Royal Society of Chemistry | ||||
| ISSN: | 1477-9226 | ||||
| Official Date: | 2009 | ||||
| Dates: |
|
||||
| Number: | No.38 | ||||
| Number of Pages: | 8 | ||||
| Page Range: | pp. 8079-8086 | ||||
| DOI: | 10.1039/b910485m | ||||
| Status: | Peer Reviewed | ||||
| Publication Status: | Published | ||||
| Funder: | Compagnie de Saint-Gobain, Engineering and Physical Sciences Research Council (EPSRC), University of Warwick |
Data sourced from Thomson Reuters' Web of Knowledge
Request changes or add full text files to a record
Repository staff actions (login required)
 |
View Item |
