A COMPARATIVE-STUDY OF THE DC CONDUCTION IN NA2O-PBO-B2O3 AND CDO-PBO-B2O3 GLASSES

Dc conductivity measurements have been carried out for yPbO. [(100 - y ) - x] B2O3. xMO and yB2O3. [(100 - y) - x] PbO.xMO glasses (mol%), wh ere MO represents Na2O or CdO. The conductivity (at 350-degrees-C) inc reases by 4-5 orders upon increasing Na2O up to 20 mol%. Different beh aviour and smaller change of the conductivity (<2 orders) is found for CdO. The change of conductivity with the oxygen to boron ratio (O/B) depends on the glass composition in the case of Na2O addition, whilst there is a common dependence on O/B for all glasses containing CdO. Th e results are discussed in terms of the destruction of the borate netw ork as Na2O is increased, whereas CdO can enter the structure as both a network former and a network modifier.