engleski

Influence of crystallization on the electrical conductivity in zinc iron phosphate glasses

Iron phosphate glasses are electronically conducting glasses with polaronic conducting mechanism what gives them potential application in electronic devices. Usually formation of glass-ceramics leads to improvement of electrical and dielectric properties. The purpose of the present study was to induce nanocrystallization by annealing and investigate the conduction mechanism before and after thermal treatments. The heat treatments were performed on the 10ZnO-30Fe2O3-60P2O5 (mol%) glass. The treatments were made in several cycles at 600 and 650 °C. After each treatment the electrical conductivity was measured using impedance analyzer over wide frequency (0, 01 Hz – 4 MHz) and temperature range (303 - 473 K). The structure was analyzed by XRD whereas microstructure was studied by SEM and TEM. Micrographs obtained by TEM and SEM indicated the formation of nanocrystal for heat treated glasses. The XRD analysis showed that the main crystalline phase was Fe3(P2O7)2. Separation of two semicircles in the complex impedance spectra, Z*(ω ), was observed indicating two processes as a result of the formation of the nanocrystals in the glass. Electrical conductivity at the room temperature increases with increasing number of nanocrystals. This effect is attributed to fast conduction at the interfaces between crystallites and glassy phase.

iron phosphate glasses; impedance spectroscopy; crystallization

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