| In the systems Pb0-B20a-S03 and Zn0-B20rS03 clear and stable glasses
containing upto about 20 mole per cent S03 were .obtained. Unlike the borate
glasses, thin films of sulphate-containing, glasses show selective infra-red tram•mission
around 12p.. Compared to the corresponding borate glasses, thermal expansion is
higher. DC resistivity, dielectric constant and soft.ening temperature do not change
significantly by replacing B20s with SOs. Addition of S03 ~mproves resistance of
lead glasses to water attack but deteriorates zinc glasses.• Some of the glasses did not
show any visible change after they were kept exposed to atmosphere for about a year. |
