Effect of highly dispersed yttria addition on thermal stability of hydroxyapatite

The capability of the colloidal method to produce yttria (Y₂O₃) dispersed hydroxyapatite (HA) has been investigated as an alternative method to the conventional method of mechanical mixing and sintering for developing HA-based materials that could exhibit controllable and enhanced functional properties. A water based colloidal route to produce HA materials with highly dispersed Y₂O₃ has been applied, and the effect of 10 wt.% Y₂O₃ addition to HA investigated by thermal analysis, X-ray diffraction and Fourier transform infrared spectroscopy. These measurements evidence a remarkable effect of this Y₂O₃ addition on decomposition mechanisms of synthetic HA. Results show that incorporation of Y₂O₃ as dispersed second phase is beneficial because it hinders the decomposition mechanisms of HA into calcium phosphates. This retardation will allow the control of the sintering conditions for developing HA implants with improved properties. Besides, substitution of Ca⁻2+ with Y⁻3+ ions appears to promote the formation of OH- vacancies, which could improve the conductive properties of HA favorable to osseointegration.This work has been supported by the Ministry of Science and Innova tion of Spain (MICINN) under contracts MAT2009 14448 C02 01 and IPT 310000 2010 12, and Regional Government of Madrid through the ESTRUMAT CM program (MAT 1585).Publicad