THE SYSTEM CAHPO4-CENTER-DOT-2H2O-CASO4-CENTER-DOT-2H2O - CRYSTALLIZATIONS FROM CALCIUM-PHOSPHATE SOLUTIONS IN THE PRESENCE OF SO42-

The crystallization from solutions of 36 x 10(-3)M in [Ca]2+ = [HPO4]2 - + [SO4]2-, with ratios [SO4]2-/[HPO4]2-ranging from 0.11 to 1, was s tudied at 25-degrees-C. When [SO4]2- was present in the starting solut ions in small amounts (ratios 0.11-0.43), only brushite, twinned follo wing the [010] direction, crystallized. The morphology and habit of th e crystals were strongly dependent on the supersaturation of the solut ion. Higher concentrations in [SO4]2- (ratios 0.66-1) allowed the crys tallization, on the brushite first precipitated, of a phase showing, b y EDS and X-ray analyses, a calcium sulphate phosphate hydrate composi tion.