Electrochemical performance of Nd1.8Ce0.2CuO4±δ mixed-ionic-electronic conductor for intermediate solid oxide fuel cells

The ball-mill assisted solid-state reaction gave nanocrystalline Nd1.8Ce0.2CuO4 +/-delta solid solution. Its crystal structure estimated by Rietveld analysis revealed decreased space in rock salt layer on partial replacement of Nd3+ by Ce4+. The dc conductivity was reduced when the sample was sintered at high temperature (at 1100 degrees C) due to random growth of the grains. The sintering temperature of the cells was optimized to 1000 degrees C in terms of lowest area-specific resistance (ASR) = 1.62 Omega cm(2). The transition from positive temperature coefficient (PTC) to negative temperature coefficient (NTC) in Nd1.8Ce0.2CuO4 +/-delta found at 630 degrees C in dc conductivity coincided with the transition in temperature dependent ASR study. The electrochemical performance of Nd1.8Ce0.2CuO4 +/-delta is discussed in the light of oxygen absorption by the lattice. (C) 2010 Elsevier B.V. All rights reserved.