Biomedical Engineering Reference
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TABLE 2.5. Crystallographic Properties of Synthetic Calcium Phosphates
Space
group
Ca/P molar
ratio
Calcium Phosphates
Molecular formula
Crystal habit
* Monocalcium phosphate
Monohydrate, MCPM
Ca(H
2
PO
4
)
2
.H
2
O
triclinic
a = 5.626 A
b = 11.889
c = 6.4728
0.5
Dicalcium phosphate
dihydrate DCPD or
brushite
CaHPO
4
.2H
2
O
monoclinic
a = 5.182 A
b = 15.18
c = 6.239
B = 116.25 °
C2/c
1.0
* Dicalcium phosphate
anhydrous Monetite
CaHPO
4
triclinic
a = 6.91 A
b = 6.63
c = 6.99
PI
1.0
Octacalcium phosphate,
OCP
Ca
8
H
2
(PO
4
)
6
.5H
2
O
triclinic
a = 19.87 A
b = 9.63
c = 6.87
PI
1.33
* Tricalcium phosphate,
β - TCP Whitlockite
Ca
3
(PO
4
)
2
hexagonal
a = 10.428 A
c = 37.378
R3c
1.50
* * Tricalcium phosphate,
β - TCMP Mg - substituted
(Ca,Mg)
3
(PO
4
)
2
hexagonal
a = 10.32 A
c = 37.00
R3c
1.50
* Tetracalcium phosphate,
TTCP
Ca
4
(PO
4
)
2
O
monoclinic
a = 7.023 A
b = 11.986
c = 9.473
P2
1
2.0
* Hydroxyapatite, HA
Ca
10
(PO
4
)
6
(OH)
2
hexagonal
a = 9.422 A
c = 6.880
P6
3
/m
1.67
* Fluoroapatite, FA
Ca
10
(PO
4
)
6
(F)
2
hexagonal
a = 9.377 A
c = 6.880
P6
3
/m
1.67
* Chloroapatite, ClA
Ca
10
(PO
4
)
6
(Cl)
2
monoclinic
a = 9.632 A
c = 7.00
C2/c
1.67
[22,64] . * Does not occur in biologic systems. * * (Ca+Mg)/P. [22,64] .
2.4.2 Dicalcium Phosphate Dihydrate (DCPD)
DCPD also referred to as brushite is represented by the formula CaHPO
4
.2H
2
O.
It can be prepared by precipitation at 25-60 °C at pH 4 to 6 or from gel systems
(Figure 2.9) [64,69]. DCPD, but not DCPA (dicalcium phosphate anhydrous,
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