Structural modifications of lanthanum silicate oxyapatite exposed to high water pressure

摘要

Dense lanthanum silicate oxyapatite samples La9.33+x(SiO4)(6)O2+3x/2 were exposed to high water pressure in autoclave, in order to study the effects of oxygen stoichiometry and treatment duration on the protonation of these materials. TG analyses showed that protonic species were successfully introduced into the bulk of the material, especially for La-9.60(SiO4)(6)O-2.4 sample after 84h of treatment at 550 degrees C under 40 bar water pressure. It was shown that the mass loss compares well with perovskite materials and increases when protonation time rises (0.66% above 600 degrees C for 408 h), with a time limit beyond which the microstructure is no more stable.