Transcript MODELING AND COMPUTATION OF HYDROXYAPATITE

PERCERAMICS
MODELING AND COMPUTATION OF HYDROXYAPATITE
NANOSTRUCTURES AND PROPERTIES
V. BYSTROV1), N.BYSTROVA2), E. PARAMONOVA1) , A.. SAPRONOVA1), S. FILIPPOV1),
1)Institute of Mathematical Problems of Byology of RAS; 2)Institute of Theoretical and Experimental Biophysics of RAS, Pushchino, 142290, Moscow region,
Russia
E-mail:[email protected]
[email protected]
http://home.impb.psn.ru (OPIT Home Page)
Hydroxyapatite (Ca5(PO4)3 OH) (HAp) is a crystal structural and compositional analogue to calcified tissues of vertebrates. The
biomedical significance of HAp is its bioactivity – HAp ceramics conduct the formation of new bone on their surface. HAp properties are
ascribed to the characteristic surface structure of HAp, while the detailed mechanism is still unknown.
Hydroxyapaptite can occur in a monoclinic phase (space group P21/b) or in
the hexagonal system (P63/m). In the monoclinic phase, all of the dipols in
all of the tunnels lying in the same plane parallel to the a,c plane must be
either all up or all down and those in the next plane b/2 away must be
oriented oppositely.
OH- dipols form so-called “OH- ion channels” along c direction. These channels
are bounded within each unit cell be two triangular arrays of Ca2+ ions and by
four triangular arrays of O2- ions, belonging to PO43- groups
a
b
c
P 63/m
~9.4
~9.4
~6.8
P 21/b
~9.5
~19
~6.8
Unit cell parameters
a,b,c [Å] HAp in
hexagonal P63/m
and monoclinic
P21/b phase
European Commission
PROJECT NMP3-CT-2003-504937
“Multifunctional percolated nanostructured ceramics
fabricated from hydroxylapatyte”
We have used data from CIF
(Crystallographic Information File) lybrary [8]
which were edited with enCIFer 1.1 [7] and
spg [6]. Then in Web Lab Viewer Lite [1] the
structures of both modification of HAp were
created from CIF. Then obtained data were
processed by Hyper Chem: OH positions
were optimized. Also in Web Lab Viewer Lite
H-bonds and Van der Waals surfaces were
plot.
V
S
P 63/m
725,3
756,5
P 21/b
1155,9
960,7
Volume V [Å3] and square S [Å2] of Van
der Waals surface of HAp cell in
P63/m and P21/b phases (WebLab
Viewer Lite)
References:
1. N. Hitmi, D. Chatain, C. LaCabanne, J. Dugas, J.C.Trombe, C. Rey and G. Montel, Solid StateCommunications, Vol. 33, pp. 10031004, 1980.
2. N. Hitmi, C. LaCabanne and R.A. Young, J.Phys. Chem. Solids Vol. 47, No6, pp533-546, 1986.
3. Nakamura, Nakeda and Yamashita, J. Appl. Phys.,Vol.89, No.10,15 May 2001. Proton transport polarization and depolarization of
hydroxyapatite ceramics
4. G.C. Maiti, F.Freund. Influence of fluorine substitution on the proton conductivity of hydroxyapatite. J.Chem.Soc. Dalton, pp.949-955,
1981
5. http://www.msi.com/viewer
6. http://www.calidris-em.com/archive.htm
7. http://www.ccdc.cam.ac.uk/free_services/encifer
8. ftp://ftp.geo.arizona.edu/pub/xtal/data/CIFfiles/