Yttria-stabilized zirconia thin films with restrained columnar grains for oxygen ion conducting electrolytes

Yttria-stabilized zirconia thin films with restrained columnar grains were deposited by modifying the DC reactive magnetron sputtering conditions. Usually, films fabricated by physical vapor deposition (PVD) method generate columnar grain structures due to its deposition characteristics. The grain boundaries between these columnar grains can be considered as structural defects and causes serious issues for the application of thin film electrolyte of energy conversion systems. By modifying the background pressure and deposition temperature of the reactive sputtering method, YSZ thin films having restrained columnar grains were successfully fabricated. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations were conducted to analyze the surface morphologies, grain structures, and nano-defects in the interior of the YSZ thin film. Through the analysis, restrained columnar microstructures of the YSZ films were deposited as dense and homogeneous. The film also showed higher ionic conductivity compared to that of the columnar structure due to the reduced ion transport blocking effect. Moreover, the fuel cell fabricated with the YSZ electrolyte having restrained columnar grains showed superior performance in terms of the peak power density than the fuel cell with columnar grain electrolyte structure.