Substitutions of praseodymium and silicon for calcium and phosphorus in hydroxyapatite structure

Substituted hydroxyapatite samples of composition Ca10-x Pr (x) (PO4)(6-x) (SiO4) (x) (OH)(2), where x = 0-6, were studied using X-ray diffraction and IR spectroscopy. Calcium substitutions occurred over the entire range of compositions studied. The crystal structure of solid solutions was refined by the Rietveld technique.