Nanocomposites and nanomaterials

Elaboration of scandia- and yttria-stabilized zirconia composite for Solid Oxide Fuel Cell application
Polishko I.O.1, Brodnikovskyi Y.M.1, McDonald N.2, Brodnikovskyi D.M.1, Brodnikovska I.V.1, Brychevskyi M.M.1, Lysunenko N.O.1, Kovalenko L.L.3, Vasylyev O.D.1, Belous A.G.3, Steinberger-Wilckens R.2
1 Frantsevich Institute for Problems of Materials Science, 3 Krzhizhanovskyi Str., Kyiv, 03860, Ukraine. 
E-mail: polishko.ihor@gmail.com   
2 University of Birmingham, Birmingham, B15 2TT, United Kingdom
3 Vernadsky Institute of general and inorganic chemistry, 32/34 Akademika Palladana Ave., Kyiv, 03142, Ukraine

Zirconia stabilized with 8-mol% Y2O3 (8YSZ) is the state-of-the-art electrolyte material for solid oxide fuel cell applications. However, despite the extensive use of 8YSZ for SOFCs, within the past decade zirconia stabilized with 10-mol. % Sc2O3 and 1-mol. % Ce2O3 (10Sc1CeSZ) has garnered much attention as one of the best ionic conductors for SOFCs operated at 600-700 °C. In the search of new electrolyte systems with high ionic conductivity, other parameters such as strength, structural and chemical stability, and cost of materials are very important if such materials are going to be used in commercial devices. In consequence of high price for 10Sc1CeSZ there are many studies are focused on combination of YSZ and ScSZ systems to improve electrolyte properties. Zirconia stabilized with 3.5-mol. % Y2O3 (3.5YSZ) provides higher strength than 8YSZ and 10Sc1CeSZ, but it doesn’t provide the enough ionic conductivity. 
The provision of improved electrolyte mechanical strength complete with sufficient ionic conductivity is possible through the use of 3.5YSZ and 10Sc1CeSZ. Thus, the present work is devoted to studying the influence of varying amounts of 3.5YSZ (33-, 40-, 50-wt. %) on the electrical and mechanical properties of a 10Sc1CeSZ-3.5YSZ composite. As a base for comparison with the 10Sc1CeSZ-3.5YSZ properties, 3.5YSZ, 10Sc1CeSZ and 8YSZ have been used. 
It was found that the solid state reaction/or redistribution of stabilizers (Sc2O3, CeO2, Y2O3) take place in 10Sc1CeSZ-3.5YSZ ceramic samples during sintering at 1400 °C for 2 h. The 10Sc1CeSZ-3.5YSZ (33-, 40-, 50-wt. %) ceramics has had lower normalized electrical conductivity at 600°C (3.2·10-3, 2.2·10-3 and 1.2·10-3 S·cm-1, respectively) and fracture strength (111, 117 and 133 MPa, respectively) comparing with 8YSZ ceramics (4.6·10-3 S·cm-1 and 247 MPa) made at the same rote and tested at the same conditions.