Abstract:
In this paper, our results on mechanochemical synthesis of ATLS are summarized.
The effect of the dopant type, its parent compound nature and amount of water on the Al and Fe-doped ATLS formation as well as possible phenomenological models of mechanism of apatitetype silicates synthesis are considered. As lanthanum and silicon sources, the La2O3 and SiO2∙nH2O have been taken. As dopant precursors, Fe- and Al-oxides and hydroxides, Fe(HCOO)3, SiO2 impregnated with nitrates have been taken. The apatite formation in the course of milling is studied by XRD, TEM, 29Si and 27Al MAS NMR, IR and UV-Vis spectroscopy.
The key role of intermediate La(OH)3 formation, acid-base reactions and double-contact generation in the many-component mixtures due to aluminum or ferrosilicate formation for the rapid MCS of doped ATLS is shown. The doped ATLS formation via the topotactic mechanism was observed in the case of mixtures containing Al(OH)3 and SiO2 impregnated with nitrates. The water presence favours fast passing of acid-base reactions, however a large quantity of water may lead to ATLS formation via the activated mixture amorphization.
Keywords:
Apatites, mechanochemical synthesis, Apatite type lanthanum silicates, ceramics, oxides
