Abstract
Optical absorption, infra-red absorption spectra and differential scanning calorimetry of amorphous (Na sub(2)B sub(4)O sub(7)) sub(80)-(Pb sub(3)O sub(4)) sub(20-x)-(CuO) sub(x) systems were studied as functions of copper content up to 10 mol%. When the Pb sub(3)O sub(4) in the glasses is gradually replaced by CuO, pronounced decrease in the optical energy gap and an increase in the optical absorption at 750 nm due to the Cu super(2+) ions is observed. The change in the optical absorption may be attributed to the concentration variation of the Cu super(2+) ions in the glasses as a consequence of changing the lead content.