ELECTRICAL AND ELASTIC PROPERTIES OF BINARY LEAD CHLOROBORATE GLASSES

Various comparative experiments on xPbCl2-(100 - x)B2O3 (20 less-than- or-equal-to x less-than-or-equal-to 45 mol%) glasses reveal that the P bCl2 does not enter the B-O network, but is inserted into interstices or voids in the glassy matrix. However, the network becomes systematic ally weakened and expanded with increasing PbCl2 concentration; this i s observed as a decrease in T(g), and an increase of both the molar vo lume and thermal expansion coefficient. The electrical conductivity me asurements of these glasses demonstrated a marked enhancement in the i onic conductivity (sigma). The maximum enhancement in a is by eight or ders of magnitude as PbCl2 replaces B2O3 (45 mol%). The drastic increa se in sigma leads us to suggest that the Cl- ions form additional migr ation pathways for Pb2+ ions, which are important for the conduction m echanisms. In addition, the activation energy associated with jumping Pb2+ ions decreases with increasing PbCl2 content; this indicates that jumps of the Pb2+ ions in the vicinity of the Cl- ions are relatively easy.