engleski

Electrical conductivity in mixed-alkali iron phosphate glasses

The electrical relaxation of mixed alkali, sodium and potassium, iron pyrophosphate 20[(1-x)K2O-xNa2O]-20Fe2O3-60P2O5 , (0 Ł x Ł 1) glasses has been studied in the frequency range from 0.1 Hz to 10 kHz and over the temperature range from 303 to 423 K. The ac conductivity as a function of the temperature has been divided into two domains, one where the absolute magnitude of ac conductivity is close to the dc conductivity and an other where the absolute magnitude of ac conductivity is larger than the dc conductivity. The thermally stimulated polarization current technique was used to study dc conductivity in these iron phosphate glasses. The dc conductivity calculated from thermally stimulated current measurements was in good agreement with the dc conductivity obtained from impedance measurements. At the same temperature, the dc conductivity varies slightly in the glasses with different sodium and potassium content. The conductivity was examined on the basis that the activation energy for electronic conduction is lower than that for ionic conduction. The conductivity in these mixed alkali iron phosphate glasses depends upon iron oxide content that suggests electronic conduction.

Electrical conductivity; mixed-alkali effect; phosphate glasses

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