Dissolution of Nb-doped hydroxyapatite prepared via low-temperature mechanochemical method: Spectroscopy studies

Abstract

Calcium phosphate glass ceramics with nominal hydroxyapatite stoichiometry doped with niobium were synthesized using simple as well as low-temperature mechanochemical method and then in the form of compressed pellet were submitted to the static dissolution process in distilled water for one month. The results of structural analysis, performed mainly on the base of spectroscopic methods such as: infrared absorption spectroscopy, energy-dispersive X-ray spectroscopy, photoelectron spectroscopy as well as soft and tender X-ray absorption spectroscopies, indicate that during the dissolution process the presence of niobium reduced the dynamics of the calcium phosphate new layer formation, without a significant impact on the morphology and stoichiometry of this layer. Moreover, the Nb addition favored the formation of hydroxyapatite and Ca-deficient hydroxyapatite, both during the synthesis and dissolution processes, and facilitated the incorporation of the CO3-2 groups into the ceramic matrix, leading to the formation of B-type carbonated apatite.