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 ± δ 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 °C) due to random growth of the grains. The sintering temperature of the cells was optimized to 1000 °C in terms of lowest area-specific resistance (ASR) = 1.62 Ω cm2. The transition from positive temperature coefficient (PTC) to negative temperature coefficient (NTC) in Nd1.8Ce0.2CuO4 ± δ found at 630 °C in dc conductivity coincided with the transition in temperature dependent ASR study. The electrochemical performance of Nd1.8Ce0.2CuO4 ± δ is discussed in the light of oxygen absorption by the lattice.

Research Highlights
► Nd2 − xCexCuO4 ± δ prepared following mechanochemically assisted solid-state sintering gives sub-micron crystallites.
► It correlates microstructure, electrical and electrochemical properties.
► Sintering temperature of electrochemical cell optimized to 1000 °C.
► Sub-micron-crystallites with uniform grain size and shape improve electrochemical performance.
► Nd1.8Ce0.2CuO4 ± δ may be a potential cathode material.