SYNTHESIS AND STRUCTURE OF CADMIUM CHALCOGENIDE BERYLLOSILICATE SODALITES

Sodalites of the composition Cd-8[BeSiO4](6)X(2), X = S, Se, and Te, h ave been synthesized by hydrothermal reaction of CdO, BeO, SiO2, and X at 750 degrees C and 2 kbar. The materials crystallize with the cubic sodalite unit cell with an ordered Be/Si framework in the space group <P(4)over bar 3n>. Their structures have been refined from powder dif fraction data in order to delineate the dimensions of the Cd(4)X units in the sodalite cage and the intercage separation of these units. Inf rared, UV-vis and Si-29 MAS NMR spectra of these materials are also re ported. Correlations between structural parameters and Si-29 chemical shifts have been determined for this series of compounds. UV-vis data demonstrate that the Cd(4)X units do not interact electronically.