LAUSR

Abstract Samples of Gd-doped ceria (GDC, Ce0.9Gd0.1O1.95) with eutectic mixtures of Na2CO3 and Li2CO3 (NLC), or K2CO3, Na2CO3 and Li2CO3 (KNLC) as sintering aids (5 mol%) were studied against pure GDC and cobalt doped GDC. The former electrolytes reached densifications in excess of 95% when sintered at 1100 °C, values comparable to pure GDC sintered at 1500 °C, and more than 20% higher than for GDC sintered at 1100 °C. X-ray diffraction powder patterns showed only typical GDC peaks without any noticeable lattice modification and microstructural analysis suggested a homogeneous distribution of residual amounts of sintering aids. The electrical properties of all materials were studied by impedance spectroscopy in air from 200 to 750 °C. Materials with NLC and KNLC showed a total ionic conductivity matching pure GDC at 600 °C. Hebb-Wagner polarization measurements, used to assess the impact of sintering aids on the n and p-type electronic conductivity of GDC (600–750 °C) showed that NLC and KNLC additions lower the p-type conductivity of GDC while Co additions have the opposite effect. The efficacy of alkali metal salts to produce ceria-based electrolytes with competitive ionic and electronic transport properties is exposed.