Ionic and electron–hole conduction in BaZr0.93Y0.07O3−δ by 4-probe dc measurements

Porous samples of composition of BaZr0.93Y0.07O3−δ were fabricated. Electrical conductivity of porous samples was measured using a 4-probe dc method over a pO2 range from 7.3 × 10−6 to 1 atm and over a temperature range from 500 to 800 °C. The results showed that the electrical conductivity increases with increasing pO2, a characteristic of electron–hole conduction. Above pO2 of 0.01 atm, the measured total conductivity was fitted to image, where σi is the ionic conductivity and image is the electronic (hole) conductivity. The activation energies were estimated to be not, vert, similar0.57 ± 0.15 and not, vert, similar1.01 ± 0.04 eV for oxygen ion and electron–hole conduction, respectively. The oxygen ion transference number ranged between not, vert, similar0.01 and 0.7 over the pO2 and the temperature ranges investigated. Electrical conductivity measurements were also carried out in H2O-containing atmospheres. It was observed that at a temperature below not, vert, similar550 °C, the predominant ionic conduction was due to protons.