Relationship between SiO2 content and electrical properties of 8-mol% Y2O3-stabilized ZrO2 electrolyte

After preparing 8-mol% Y2O3-stabilized ZrO2 electrolytes with SiO2 contents to < 40, 550, 1200, and 2800 ppm and attaching Pt electrodes, a direct-current (DC) load test wherein 1 V was applied at 800 °C in air atmosphere for 1000 h was conducted to investigate the effect of SiO2 on the electrical properties. The DC resistance at 800 °C for all samples increased immediately after the test was started, but tended to stabilize over time, and remained almost constant after approximately 600 h. The bulk and the grain-boundary resistances measured by the AC complex impedance analysis at 300 °C after the DC voltage load test were increased in all samples compared to that before the test, but no clear correlation was found between the amount of SiO2 and the resistance. Moreover, the electrode interface resistance measured by complex impedance analysis at 800 °C also increased after the DC voltage load test.