Electrical properties in WO_3 doped Bi_4Ti_3O_(12) materials

摘要

Electrical conductivity decrease observed in BIT-based materials doped with W~(6+) is consistent with a lowering of both oxygen vacancies and hole concentration. The dielectric anomaly observed in BIT at temperatures below T_c decreases and finally disappears with the donor doping. Following the same trend, dielectric losses fall when the amount of dopant increases and remain in low values up to high temperatures. Compared to undoped BIT, substitution of Ti~(4+) by W~(6+) leads to a decrease of 2-3 orders of magnitude in the electrical conductivity. The average activation energy for the electrical conductivity depends on the microstructure, specifically on the aspect ratio (length/thickness) of the plate-like grains. This is because the conduction mechanism in the ab planes is different to that of the c-axis, mixing ionic and p-type conductivity, respectively.