Solid-state 31 P/ 27 Al and 31 P/ 23 Na TRAPDOR NMR experiments have been used to investigate the spatial distribution of aluminum and sodium cations with respect to the phosphate backbone for a series of sodium aluminophosphate glasses, xAl 2 O 3 ‚50Na 2 O‚ (50-x)P 2 O 5 (0 e x e 17.5). From the 31 P/ 27 Al and 31 P/ 23 Na TRAPDOR data gathered, information about the medium-range order in these glasses was obtained. The expanded data allow for better identification and interpretation of the new resonances observed in the 31 P MAS NMR spectra with the addition of aluminum. The results of these experiments show that the sodium phosphate distribution remains relatively unchanged for the glass series and that the addition of aluminum occurs primarily through the modification of the phosphate tetrahedral backbone in the melt.

Zinc polyphosphate glasses were examined as potential candidates for low temperature sealing applications. Glass-formation and properties were determined for the ZnO-P205, ZnO-B203-PZOS, and Zn0-Sn0-P205 systems, and information about the short-range structures of these glasses was obtained by Raman and solid state nuclear magnetic resonance spectroscopies. In general, the most durable polyphosphate glasses have structures based on relatively short pyrophosphate chain lengths (Le., 2 P-tetrahedra). Modified phosphate compositions are given, including compositions used to seal float glass substrates at temperatures as low as 500°C.

The LTCC samples used in this study were obtained directly from the manufacturer (Dupontt) in the laminated configuration. The forming process conditions are considered proprietary and will not be addressed in this paper.

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