Lanthanhaltige Silicate und Germanate als Halogen- und Oxyapatite

Lanthanum Containing Silicates and Germanates as Halogen Apatites and Oxyapatites Halogen apatites M₄La₆(XO₄)₆Z₂ and oxyapatites M₂La₈(XO₄)₆O₂ have been prepared: M = Sr, Pb, Ba; X = Si, Ge, and Z = F, Cl. The lattice parameters are discussed. The i.r. active internal vibrations of the silicate ion are assigned. A translational vibration of the “free” oxide ions in the oxyapatites causes an intense absorption at about 400 cm^?1 (silicates) and 350 cm^?1 (germanates), resp. The products “M₃La₆(XO₄)₆” and “M₄La₆(XO₄)₆O” are mixtures of various phases. Their respective apatite phase is a solid solution between M₂La₈(XO₄)₆O₂ and the defect apatite M₄La₆(XO₄)₆O□. Its composition mostly approximates to M₂La8(XO₄)₆O₂, however.