Dear all,
Here are some papers on Rietveld refinement of
neutron powder diffraction patterns of natural,
synthetic and substituted apatites:
1. "Neutron powder diffraction studies of silicon
substituted hydroxyapatite", Th. Leventouri, C.
E. Bunaciu, V. Perdikatsis, J. Biomat. 24,
4205-11 (2003).
2. "A Comparison of Crystal Structure Parameters
of Natural and Synthetic Apatites from Neutron
Powder Diffraction", Th. Leventouri, B. C.
Chakoumakos, N. Papanearchou, V. Perdikatsis, J.
Mat. Res. 16, 2600-06 (2001).
3. "Powder neutron diffraction studies of a
carbonate fluorapatite", Th. Leventouri, B. C.
Chakoumakos, H. Y. Moghaddam, V. Perdikatsis, J.
Mat. Res. 15, 511-7 (2000).
and a relevant:
Synthetic and Biological Hydroxyapatites:
Crystal Structure Questions ", Th. Leventouri, J.
Biomat. 27, 3339-3342, (2006).
Try searching PubMed for materials such as
apatites with biological/medical interest eg
"Rietveld structure refinement of precipitated
carbonate apatite using neutron diffraction
data".
Wilson RM, Elliott JC, Dowker SE, Smith RI.
(2004) Biomaterials. 25(11), 2205-13.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&list_uids=14741636&dopt=Citation
According to the above, carbonate replaces some
of the phosphate resulting in average shrinking
of these tetrahedra. They also located what
might be the water from their neutron
refinement, which you won't see if you are using
X-rays :-)
Alan.
At 03:57 23/05/2007, Leandro Bravo wrote:
I´m refining a sample which contains a
hydroxycarbofluorapatite (solid solution). I´m
refining it using CIF files from the ICSD, but
it´s not working so well, because they don´t
have the file for the hydroxycarbofluorapatite.
So I´m using in the TOPAS the following files:
fluorapatite, carbofluorapatite,
hydroxyfluorapatite and hydroxyapatite. When
using them the rwp is about 16 but when using
only the hydroxyapatite the rwp is 30. I´d
would like to know if any of you have very good
quality STR files of hydroxyapatite,
fluorapatite and carboapatite, or only one file
of hydroxycarbofluorapatite?!
_____________________________________________________________
Dr Alan Hewat, ILL Grenoble, FRANCE<[EMAIL PROTECTED]>fax+33.476.20.76.48
+33.476.20.72.13 (.26 Mme Guillermet) http://www.ill.fr/dif/people/hewat/
_____________________________________________________________
--
Dr. Theodora Leventouri
Professor of Physics
Physics Department, FAU
Boca Raton, FL 33431
Phone: 561-297-2695
Fax: 561-297-2662
