Influence of carbonate and nickel(II) concentration on the synthesis of calcium phosphates

GÜIDA, J.A.; BIANCHI, A.E.; GUERRA-LÓPEZ, J.R.; PUNTE, G.

JOURNAL OF SOLID STATE CHEMISTRY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2018 vol. 267 p. 98 - 105

0022-4596

Two sets of Ni-substituted calcium phosphate were synthesized by precipitation method at pH = 7 and at twodifferent concentrations of ion carbonate (CO32-) in solution and Ni(II) concentrations lower than 15%. Theproduced solids were characterized by chemical analysis, infrared spectroscopy, x-ray powder diffraction andscanning electron microscopy. The solid samples obtained at low concentration of CO32- (5%) and Ni(II)concentrations 5%, 10% and 15% were synthesized at 25 and 37 °C. All solids showed the presence of a stableand crystalline brushite (CaHPO4·2H2O). The samples synthesized in presence of high levels of carbonate (50%)and Ni(II) concentration 5% at 25, 37 and 100 °C vary with temperature. Those obtained at the lowertemperatures (25 and 37 °C) showed coexistence of two phases: a crystalline CaCO3 and carbonate apatite withlow crystallinity. At 100 °C, only carbonate apatite could be recognized. Data supported the carbonate substitution by OH- (position A) and PO43- (position B) in the hydroxyapatite structure. The comparison of the chemical analysis results of both systems studied (Ni,Ca) apatite and (Ni,Ca) carbonate apatite evidences a rise of Ni(II) incorporation in the apatite lattice, with simultaneous inclusion of CO32- and temperature increase.The obtained results suggest that brushite kidney stones development may be induced by the presence of traces of Ni(II) and simultaneous decrease of carbonate levels in the biological fluids.