Locations of metal ions in the new glasses in the alumina-calcia-monazite (LaPO$_{4})$ system

The new group of glasses synthesized from calcium aluminate (CaAl$_{2}$O$_{4})$ or C12A7 (CaO)$_{12}$(Al$_{2}$O$_{3})_{7}$ with varying fractions of La-monazite (LaPO$_{4})$ has been characterized by electron microscopy, $^{31}$P and $^{27}$Al NMR, Raman scattering and chemical methods. These techniques have yielded information concerning the environments of the metal ions Al and La in the glasses. A substantial negative shift of the principal $^{31}$P NMR line at all monazite fractions, along with Raman spectra showing that PO$_{4}$ groups do not share bridging oxygens, places La within the second coordination shell surrounding P. P-Al TRAPDOR double NMR experiments show that aluminum and phosphorus are also closely coordinated, accounting for a second, more negatively shifted line in the $^{31}$P single resonance spectra. Models for the structures of these glasses have been constructed for a range of monazite contents, and will be presented.