The analysis of the structure of bismuth gallate glasses using laser induced ionisation time-of-flight mass spectroscopy is reported in this paper. This technique has allowed for observations of the larger, intermediate range units (mesounits) present in these glasses in both negative and positive ion mass spectra. The results point to a mixed network with highly co-ordinated gallium oxide units and low coordination bismuth oxide groups. Metallic bismuth clusters of up to 4-5 atoms are also seen in the spectra. The results with lead gallate and with the time-of-flight spectra of bismuth borate glasses were compared, where different mesounits are observed, and carried out preliminary MOPAC computer calculations of the stability of the bismuth gallate fragments.
