Acoustic Debye temperature of the ternary borate glass system xPbO–(45-x)CuO–55B2O3 was studied in the composition range x = 5 - 40 mol % by using ultrasonic pulse-echo technique. The composition dependence revealed broad humps at 20mol % PbO. Below 20mol%,all Pb+2 ions are considered to be entering the borate network as a glass modifier. This transforms the borate network from an open structure to a denser three-dimensional structure due to BO3 → BO4 conversion. The addition of PbO beyond 20 mol% results in the formation of PbO4 structural units and B–O–Pb linkages in addition to NBOs. This weakness the glass structure and decreases the acoustic Debye temperature. A correlation between acoustic Debye temperature and compositional parameters was achieved when the change in boron coordination numbers is taking into account.
The compositional dependence of acoustic Debye temperature has been studied in lead copper borate glasses with molar composition xPbO–(45-x)CuO–55B2O3 glasses (5 ≤ x ≥ 40mol %). Below 20 mol%, Pb+2 ions is considered to be enter the borate network as a network modifier and this changes the coordination number of boron from 3 to 4, which stiffness of the glass network greatly. Beyond 20 mol % PbO, the decrease of acoustic Debye temperature is attributed to the creation of NBOs. Correlation between acoustic Debye temperature and total packing density of the glass was achieved.