Analysis of the structure of lead borosilicate glasses using laser ionization time of flight mass spectroscopy

We report on high resolution laser ionization time-of-flight mass spectrosc opy (LITOF-MS) measurements of lead borosilicate and sodium-doped lead boro silicate glasses. This technique permits the observation of intermediate ra nge mesounits, and provides new insights into the glass network structure. In lead borosilicates we observed strong mixing of borate and silicate grou pings, a likely absence of diborate units, and the formation of boroxol rin gs with one lead cation (PbB3O6) at borate-rich compositions. The spectra a lso suggest the growth of a limited lead oxide subnetwork at high Pb conten ts. In the sodium-doped glasses we see a preference of the sodium for boron units, and the simultaneous appearance of sodium-containing silicate units between 10 and 24 mol%, Na2O, though borate association remains predominan t. The reedmergnerite unit (BSi4O10) is seen in very small amounts in both glass families. (C) 2001 Published by Elsevier Science B.V.