Ca2+, PO43−⇌Ln3+, SiO44− coupled substitution in the apatitic structure: stability of the mono-silicated fluor-britholite

Abstract

Synthetic crystals of mono-silicated fluor–britholite doped with rare earth elements have been prepared. The stoichiometry of the compound has been determined by means of microprobe analyses. Single crystal Laue diffraction and luminescence measurements reveal the covalent character of the rare-earth channel anion bond, thus explaining the stability of such compounds in the natural environment.