Linear impedance of 35P2O5-30Fe2O3-20Nb2O5-15TiO2

The electrical properties of phosphate-iron glasses containing niobium and titanium were investigated. Glass samples of the composition of 35P2O5-30Fe2O3-20Nb2O5-15TiO2 (in %mol) were prepared by the conventional melt quenching technique. Appropriate amounts of reagents ((NH4)2HPO4 (≥99.9%, POCH), Fe2O3 (≥99.9%, POCH), Nb2O5 (≥99.9%, PLUKA AG) and TiO2 (≥99.9%, anatase and rutile mixed, PROLABO)) were thoroughly mixed in an agate mortar and put on electric stove in temperature of 573K in order to carry out the decomposition process of (NH4)2HPO4. Next powders were melted in porcelain crucibles at 1573 K for 1-2 h. The melts were poured on preheated (to 573 K) brass plate and pressed by another plate to obtain flat circular samples (dimensions: 1-2 mm thick, 20-30 mm in diameter). The obtained pellets were annealed at 673 K for 1 h and cooled with furnace. For the electrical measurements gold electrodes were evaporated at the polished samples. Impedance measurements were carried out in the frequency range from 1 mHz to 1 MHz with the ac voltage of 1 Vrms in the temperature range from 153 K to 423 K with the Novocontrol Concept 40 broadband dielectric spectrometer.
Detailed information can be found in: doi: 10.1016/j.proeng.2014.12.488