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

Abstract

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·SiO2---4PbO· SiO2 has been reinvestigated. The obtained results agree with earlier findings except for the tetrameric chain anion [SiO4O13]10-, which had not been found before. Crystallization of glassy PbO·SiO2 proceeds via the formation of low-molecular silicate anions [Si2O7]6-, [Si4O13](II)10- and [Si7O22]16-, which characterize the low-temperature crystalline polymorph T---PbO·SiO2. Further heat treatment turns T---PbO·SiO2 into alamosite, characterized by polysilicate chain anions [SiO32-]8.