engleski

Electrical Conductivity in Bismuth Iron Phosphate Glasses

The electrical properties of Bi2O3-Fe2O3-P2O5 glasses were measured by impedance spectroscopy in the frequency range from 0.01 Hz to 3 MHz and over the temperature range from 303 to 473 K. It was shown that the dc conductivity strongly depends on the Fe2O3 content and Fe(II)/Fetot ratio. With increasing Fe(II) ion content from 17 to 34 % in the Bi2O3-Fe2O3-P2O5 glasses containing up to 10 mol% Bi2O3, the dc conductivity increases. On the other hand, the decrease in dc conductivity for the glasses with 20 mol% Bi2O3 is attributed to the decrease in Fe2O3 content from 30 to 20 mol%, which indicates that the conductivity for these glasses depends on Fe2O3 content. The conductivity for these glasses is independent of the Bi2O3 content and arises mainly from polaron hopping between Fe(II) and Fe(III) ions suggesting an electronic conduction. The Raman spectra show that the addition of up to 20 mol% of Bi2O3 does not produce any changes in the glass structure which consists predominantly of pyrophosphate units.

Electrical conductivity; Bismuth phosphate glasses; Impedance spectroscopy

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