Y 2 O 3 ‐Doped Bi 2 O 3 –Y 2 O 3 ‐Stabilized ZrO 2 Composite Ceramic Electrolytes Fabricated by Infiltration

To increase the ionic conductivity of the conventional solid oxide cell (SOC) electrolyte, yttria stabilized zirconia (YSZ), we propose to fabricate yttria‐doped bismuth oxide—YSZ (YDB–YSZ) composite electrolytes by infiltrating liquid YDB precursor into porous YSZ scaffolds, followed by a heat treatment step. Comparing YDB–YSZ electrolytes fabricated via co‐sintering of the respective powders and those by infiltration, after heat treatment at the same temperature, the latter consisted of monoclinic zirconia and cubic YSZ phases, yielding electrical conductivities even lower than the conventional YSZ. Meanwhile, YDB–YSZ fabricated via infiltration yielded an interconnected network of ionically conductive tetragonal bismuth oxide phase within the cubic YSZ matrix. Consequently, electrical conductivities ca. 2.5 times that of the single‐phase YSZ was determined. The results obtained here suggest that YDB–YSZ composites are promising alternatives to single‐phase YSZ as SOC electrolytes and infiltration is preferable to fabricate these composite SOC electrolytes over the powder‐co‐sintering route.