Mg-substituted hydroxyapatite nanopowders: Synthesis, thermal stability and sintering behaviour

摘要

This paper reports a systematic investigation on Mg-substituted hydroxyapatite (Ca_(10-x)Mg_x(PO_4)_6(OH)_2) nanopowders produced by precipitation of Ca(NO_3)_2 centre dot 4H_2O and Mg(NO_3)_2. The Mg content ranged between 0.6 and 2.4 wt%. Semicrystalline Mg-substituted hydroxyapatite powders made up of needle-like nanoparticles were obtained, the specific surface area ranged between 87 and 142 m~2/g. Pure hydroxyapatite nanopowder decomposed around 1000 deg C. Mg-substituted hydroxyapatites were thermally stable up to 660 deg C (x = 1.0), 760 deg C (x = 0.5) and 840 deg C (x = 0.25) showing a distinct decreased thermal stability with respect to the pure sample. A relevant displacement of the sintering curve at lower temperature as a function of Mg content was observed, comparing to the behaviour of a pure HAp material, synthesized following the same procedure, and ascribed to the beta-TCP formation.