Oxygen (red spheres) migrates from one vacancy to another inside the scandia-doped cubic zirconia. In this new SOFC material, the oxygen must brush past cations (marked by the letter E).
The DOE Pulse reported that, using specialized cubic zirconia, scientists from Nanjing Normal University in China and Pacific Northwest National Lab created a membrane that could drop the temperature inside solid oxide fuel cells. Lowering the temperature means these cells could be built from less expensive materials.
Currently, the temperature inside SOFCs is about 1,000°C. With this much heat, the cells must be constructed using very durable and expensive ceramics. The team, led by NNU’s ed by Zhongging Yu, says its new scandia-doped cubic zirconia can work at temperatures as low as 650°C.
Using oxygen-plasma-assisted molecular beam epitaxy, the researchers grew scandia-stabilized zirconia films on sapphire substrates. The films were examined using x-ray diffraction, electron spectroscopy and microscopy.
The team used theoretical calculations and computational models to determined that nanoscale, nanosecond interactions occurring in the scandia-doped cubic film conducted oxygen faster than the yttrium doping in current electrolytes.
They say their work provides a fundamental understanding of how ions move in scandia-doped zirconia, and shows the material is very stable. “Our integrated approach takes the science to the next level,” says Theva Thevuthasan, who worked on the project and currently oversees the deposition and microfabrication capability at Environmental Molecular Science Lab at PNNL.
According to a PNNL news release, the group also has high hopes for another SOFC material made from nanolayers of zirconia and ceria.