The precipitation of calcium phosphate upon rapid mixing of solutions of Ca
Cl2 and KH2PO4-K2HPO4 was followed by pH and other quantitative measurement
s and the examination of the precipitate in the polarizing microscope. The
experiments were carried out at 25 degrees C in the presence and absence of
a static magnetic field of 0.27 T. It was found that the magnetic field in
creased dissolution of metastable precursor phases and increased nucleation
of more stable phases. This was a general tendency for the transformation
sequence: ACP --> brushite --> OCP --> HAP at initial pH approximate to 6.5
and total concentrations C-Ca = C-P = 25, 50 or 100 mM. Crystallization up
on slow diffusion of ions from a solution of CaCl2 into silica hydrogel con
taining dissolved KH2PO4-K2HPO4 was followed by recording the number and po
sitions of appearing brushite crystals and Liesegang rings. The experiment
was performed in the presence and absence of magnetic fields in the range 0
.08-0.3 T and the following conditions: room temperature, initial pH of the
gel between 5.5 and 6.8, and C-Ca = C-P = 50mM. Magnetism increased nuclea
tion of brushite in the experiments at low initial pH. The dependence on fi
eld strength was not significant, and no effect was found in experiments wi
th high initial pH. (C) 2000 Elsevier Science B.V. All rights reserved.