Assessment of processing route on the performance of ceria‐based composites

Abstract

Gd-doped ceria (GDC)-based composites, including a eutectic mixture of lithium and sodium carbonate (NLC) as second phase, were prepared using several processing routes, namely chemical synthesis, co-firing of both phases, or impregnation of a presintered porous matrix. LiAlO 2 -based composites were also prepared and used as reference. The structural, microstructural, and electrical properties (impedance spectroscopy in air, up to 700 C) of these materials were assessed in detail. A limited set of compositions was also used in measurements of total electrical conductivity at different oxygen partial pressures (from 0.21 to <10 −25 atm), in the 600 C to 700 C range. The results obtained confirmed the enormous impact of the processing route on the percolation of the ceramic phase. In the exploited range of operating conditions, GDC-NLC composites prepared by infiltration of molten carbonates within a mechanically robust ceramic matrix exhibit a high total ionic conductivity strongly influenced by the contribution of the molten salt while the ceramic phase is decisive in the appearance of a significant component of electronic conductivity under reducing conditions.

One step densification of SDC—Na2CO3 nano‐composite electrolytes for SOFC applications by cold sintering process

“…Therefore, ionic conductivity values in these composites could be further improved if the particle growth in the composites during processing could be prevented to ensure a high interterfacial area density. [33][34][35]11 Based on the knowledge so far, a nano-composite in which the nano-sized samarium doped ceria, Sm doped ceria (SDC), phase dispersed in an alkali carbonate matrix would be an ideal electrolyte in making SOFCs. If such high conduction path exists, then there is still room to further enhance the ionic conductivity of these composite electrolytes.…”

“…As a result, the inorganic doped ceria particles may coarsen and the intefacial area density in the composite will be drastically reduced. Therefore, ionic conductivity values in these composites could be further improved if the particle growth in the composites during processing could be prevented to ensure a high interterfacial area density 33–35,11 . Based on the knowledge so far, a nano‐composite in which the nano‐sized samarium doped ceria, Sm doped ceria (SDC), phase dispersed in an alkali carbonate matrix would be an ideal electrolyte in making SOFCs.…”