Structural analysis of the thermal conversion of metal chlorides into phosphate glasses

The conversion reaction of metal chlorides (NaCl, KCl, PbCI2, CdCl3) into p hosphate glasses is studied via a structural approach. The glass compositio ns are: Na: 8.5-15.4% K: 7.4-13.2%; Pb: 1.6-2.6%; Cd: 0.4-0.7%; Cl: 0.2-20. 1%; P: 11.6-20.4%; O: 36.5-60.8% (at, mol%). P-31 magic-angle-spinning nucl ear magnetic resonance and P-31 double quantum analyses are employed for de termining the structural evolution of the phosphate network as function of the batch composition and the melting temperatures (700 degrees C and 900 d egrees C), The Q(1)/Q(2) ratios, measured by P-31 spectrum deconvolution, a re in accordance with the elemental analyses of the samples prepared at 700 degrees C and 900 degrees C. Na-23 magic-angle-spinning nuclear magnetic r esonance shows the presence of sodium in the amorphous phases and in NaCl c rystals in devitrified samples. Transfer of populations in double-resonance experiments (TRAPDOR) are also consistent with the hypothesis that there i s no specific bonding of sodium to a particular Q(n) unit in the phosphate network. (C) 2000 Elsevier Science B.V. All rights reserved.