Determination of silicate anion constitution in glassy and crystalline lead silicates using an improved TMS technique

Using the DMF trimethylsilylation technique developed by Tamás, Sarkar and Roy, the distribution of silicate anions in lead silicate glasses of the composition range PbO·SiO 2 4PbO· SiO 2 has been reinvestigated. The obtained results agree with earlier findings except for the tetrameric chain anion [SiO 4 O 13 ] 10− , which had not been found before. Crystallization of glassy PbO·SiO 2 proceeds via the formation of low-molecular silicate anions [Si 2 O 7 ] 6− , [Si 4 O 13 ] (II) 10− and [Si 7 O 22 ] 16− , which characterize the low-temperature crystalline polymorph TPbO·SiO 2 . Further heat treatment turns TPbO·SiO 2 into alamosite, characterized by polysilicate chain anions [SiO 3 2− ] ∞ .