Measurements of the electrical conductivity, using ac complex impedance techniques and 22Na tracers (table 102), were performed on (1−x)GeO2-xNa2O glasses, with x = 0.0006 to 0.156. Attractive interactions between the positive alkali ions and the negative charge-compensating centers caused successive jump directions of the alkali ions to become correlated. The negatively-charged centers were suggested to correspond to the 6-fold coordinated sites formed upon adding alkali oxides to GeO2. These negatively-charged trapping centers corresponded to non-bridging O sites in alkali silicate glasses.

 

Electrical Conductivity and Tracer Diffusion in Sodium Germanate Glasses. M.P.Thomas, N.L.Peterson: Solid State Ionics, 1984, 14[4], 297-307

Table 102

Diffusion of 22Na in GeO2-Na2O Glasses

 

Na2O (mol%)

Temperature (C)

D (cm2/s)

0.20

302.3

1.61 x 10-11

0.66

302.3

1.11 x 10-11

0.97

302.2

9.20 x 10-12

1.99

302.7

5.96 x 10-12

5.08

302.3

1.90 x 10-12

7.47

302.8

9.47 x 10-13

8.77

302.4

9.03 x 10-13

15.61

302.3

4.57 x 10-12