Effect of CaO concentration on enhancement of grain-boundary conduction in gadolinia-doped ceria |
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| Authors: | Pyeong-Seok Cho Sung Bo Lee Yoon Ho Cho Doh-Yeon Kim Hyun-Min Park Jong-Heun Lee |
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| Affiliation: | aDepartment of Materials Science and Engineering, Korea University, Anam-dong, Sungbuk-ku, Seoul 136-713, South Korea;bSchool of Materials Science and Engineering, Seoul National University, Seoul 151-744, South Korea;cNew Materials Evaluation Center, Korea Research Institute of Standards and Science, Taeduk Science Town, Daejeon 305-600, South Korea |
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| Abstract: | This study examines the effect of calcium oxide (CaO) addition to Ce0.9Gd0.1O1.95 (gadolinia-doped ceria, GDC) containing 500 ppm SiO2 on grain-interior and grain-boundary conduction. The GDC can be used as a solid electrolyte for intermediate and low-temperature solid oxide fuel cells. Doping with ≥2 mol% CaO results in a decrease in apparent grain-boundary resistivity at 300 °C from 746.7 kΩ cm to 2.8–3.5 kΩ cm. The total resistivity exhibits a minimum at 2 mol% CaO. Further increase in CaO concentration to 10 mol% results in an increase in grain-interior resistivity from 3.1 to 40 kΩ cm. Although most of the CaO is incorporated into the GDC lattice, a small amount of CaO scavenges the intergranular siliceous phase, which leads to a significant increase in grain-boundary conduction. The increase in grain-interior resistivity at high CaO concentration is attributed to defect association between VO and CaCe″. |
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| Keywords: | Gadolinia-doped ceria (GDC) Grain-boundary conduction Scavenging effect Solid oxide fuel cell Calcium oxide |
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