Effect of alumina additions in YSZ on the microstructure and degradation of the LSM–YSZ interface

Influence of alumina impurities on microstructure of LSM–CeO2 composites

“…Although the ceria grain boundary remains apparently clean from SEM and AFM observations, some boundaries inside the bulk material may be coated by a layer of (Mn,Al) 3 O 4 that is 10 nm thick. Similar spinel phase formation at the interface between cathode and electrolyte was previously observed by Knibb et al in the SOFC system with composite electrolyte containing YSZ-Al 2 O 3 and LSM [25]. It has been reported that the formation of Mn-Al spinel phases results in considerable loss of the oxygen transfer capability of the materials that can significantly increase the cathode overpotential and degrade the cell performance [25,34,36].…”

“…Al 2 O 3 has previously been intentionally added to the electrolyte to improve the mechanical properties and cell integrity. It has been reported that the addition of Al 2 O 3 improves the strength of t-YSZ, but the conductivity decreases considerably with alumina contents N10 wt.% [25]. The conductivity of heterogeneous specimens of YSZ with a small amount of Al 2 O 3 is higher because of the increased mobility of oxygen vacancies.…”

“…The presence of Al 2 O 3 in SOFC materials may have both beneficial and detrimental effects on the cell performance [23,25]. Al 2 O 3 has previously been intentionally added to the electrolyte to improve the mechanical properties and cell integrity.…”

“…Other than silica, degradation phases are known to include zirconate phases such as lanthanum zirconate (La 2 Zr 2 O 7 ) and strontium zirconate (SrZrO 3 ) at the interface between the LSM cathode and YSZ electrolyte [3,17,22,23]. Sometimes alumina is added to YSZ to improve the strength of the electrolyte and grain boundary conductivity [24,25]. It has been reported that the addition of 10 wt.% Al 2 O 3 to YSZ could increase the fracture strength, improve mechanical properties, and reduce the operating temperature of the SOFC [25].…”

“…Sometimes alumina is added to YSZ to improve the strength of the electrolyte and grain boundary conductivity [24,25]. It has been reported that the addition of 10 wt.% Al 2 O 3 to YSZ could increase the fracture strength, improve mechanical properties, and reduce the operating temperature of the SOFC [25]. However, maintaining clean TPBs could then be a critical issue since the alumina addition may react with the elements of electrode and electrolyte to form secondary phases that reduce the interfacial integrity and stability of the SOFC [25].…”