Iron/zinc doped 8 mol% yttria stabilized zirconia electrolytes for the green fuel cell technology: A comparative study of thermal analysis, crystalline structure, microstructure, mechanical and electrochemical properties

Abstract

Abstract Pristine and Fe/Zn doped 8 mol% yttria stabilized zirconia (8YSZ) were prepared by ball milling technique for potential application in the green fuel cell technology. The series consisted of (8YSZ)0.97(Fe2O3)x(ZnO)3-x, where x indicates 0.5, 1.0, 1.5, 2.0 and 2.5 mol% Fe or Zn alternatively. A number of analytical techniques were used to characterize 8YSZ included X-ray diffraction, scanning electron microscopy, impedance spectroscopy, dilatometer, and hardness test. The analytical results indicated a decrease in the densification in the doped 8YSZ as the activation energy for densification decreased from 1087 kJ/mol in the pristine 8YSZ sample to 264 kJ/mol in the doped 8YSZ. The optimum doped 8YSZ was recognised with 2.0 mol% Fe and 1.0 mol% of Zn exhibit the highest percentage of the cubic phase approaching 62.4 wt%, while the shortest lattice parameter of 0.5132 nm and crystallite size equivalent to 26.34 nm. This composition also indicated pore-free morphology, the highest densification up to ∼94%, the greatest hardness value (above 740 MPa), while improve total conductivity about 7.398 × 10−6 S/cm at 300 °C. The results provide new insights on the effect of mixed dopants as ceramic composite as well as on the fuel cell technology.