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iii. restricted citric acid/Ca molar ratio (1.2 1.31),
iv. higher temperature (180 C) and longer duration (2.75 h at 200 C),
v. final pH of 3.4 3.8.
Lactic acid
H 3 PO 4
Ca(OH) 2
(Ca-lactic complexes, no precipitate)
Homogeneous solution
Hydrothermal treatment
(200ºC, 5 h, 2 MPa)
Suction filtration, washing, drying
HAp whiskers
(Ca/P = 1.59 1.62)
XRD, SEM, IR, Raman
determination of Ca/P ratio
HAp whiskers
(Ca/P = 1.61)
CaCO 3
(35 70 wt%)
Mixing in NH 3 OH solution
(2 h, pH = 11)
Homogeneous
mixture
Reaction
at 600ºC (1 72 h)
Dissolution of CaCO 3 , CaO
in 0.2 M triammonium citrate solution
(pH = 8, 24 h)
HAp whiskers
(Ca/P = 1.64
1.67)
XRD, SEM, IR, Raman
determination of Ca/P ratio
Figure 10.68 Steps involved in the experimental procedure for the preparation of HAp [335] .
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