Scandia-stabilized cubic zirconia

Alternatively, SZY electrolytes, Zr02 stabilized with other compounds, have been studied. An example is the Scandia-stabilized cubic zirconia (ScSZ) [170]. 

Zirconia (Zr02) stabilized in its high temperature, cubic form by addition of 8 to 12 mol.% yttria or scandia is currently the materials of choice in devices utilizing a solid-state oxide ion conducting electrolyte, eg oxygen sensors, oxygen pumps and solid oxide fuel cells (SOFCs), because of its good oxide ion conductivity and redox resistance [1-4]. Improvements in conductivity, however, are necessary to enhance theirs performance and efficiency. 

The method of sintering is also important for the phase content, densification, and ionic conductivity. This was well demonstrated for zirconia stabilized with 10 mol% scandia and 1 mol% ceria. Changing the temperature and time [33], a rhombohedric phase was detected in the 1150-1300 °C range, while conventionally sintered pellets, after 2h at 1200 °C, showed a cubic single phase. 

Yttria also possesses a cubic structure similar to zirconia. This is the main reason for the formation of a solid solution in such a wide range of concentrations of the zirconia-3ritria system. Yttria-stabilized zirconia can be obtained as a solid solution with an yttria content between 6 and 50mol%. Other oxides, especially rare-earth oxides, are expected to have a similar cubic phase stabilizing effect. The oxides are scandia and rare-earth oxides with the atomic number from 62 to 71, since those metals are stable in the trivalent state. In fact, the cubic form of zirconia can be obtained in stable form by mixing any one of the rare-earth oxides such as scandia, samaria and gadolinia. The minimum amount of... 

---