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Crystallization of Calcium and Magnesium Phosphates from Solutions of Medium and Low Concentrations
Author(s) -
Abbona F.,
FranchiniAngela M.,
Boistelle R.
Publication year - 1992
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170270107
Subject(s) - brushite , whitlockite , magnesium , calcium , supersaturation , precipitation , amorphous calcium phosphate , chemistry , crystallization , struvite , phosphate , nuclear chemistry , inorganic chemistry , mineralogy , biochemistry , physics , organic chemistry , meteorology
Calcium phosphates are precipitated at 25 °C from solutions of medium (Ca = P = 50 mM) and low (Ca = P = 10 mM) concentrations in the presence of magnesium. Experiments are also performed with solutions in which Ca + Mg = P = 50 mM and Ca + Mg = P = 10 mM. An amorphous calcium phosphate, Ca 3 (PO 4 ) 2 · nH 2 O, and brushite, CaHPO 4 · 2 H 2 O, are the phases first nucleated. The phases occurring one year later are brushite in the more concentrated solutions, hydroxyapatite (Ca 5 OH(PO 4 ) 3 ) and whitlockite (Ca 9 MgH(PO 4 ) 7 ) in the others. Octacalciumphosphate, Ca 8 H 2 (PO 4 ) 6 · 5H 2 O, occurs as transitory phase. The effects of concentration, pH, supersaturation and magnesium on the precipitation and evolution of calcium phosphates, and the conditions for phase stability are discussed.