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

Abstract The conversion reaction of metal chlorides (NaCl, KCl, PbCl 2 , CdCl 2 ) into phosphate glasses is studied via a structural approach. The glass compositions 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%). 31 P magic-angle-spinning nuclear magnetic resonance and 31 P double quantum analyses are employed for determining the structural evolution of the phosphate network as function of the batch composition and the melting temperatures (700°C and 900°C). The Q 1 /Q 2 ratios, measured by 31 P spectrum deconvolution, are in accordance with the elemental analyses of the samples prepared at 700°C and 900°C. 23 Na magic-angle-spinning nuclear magnetic resonance shows the presence of sodium in the amorphous phases and in NaCl crystals in devitrified samples. Transfer of populations in double-resonance experiments (TRAPDOR) are also consistent with the hypothesis that there is no specific bonding of sodium to a particular Q n unit in the phosphate network.