Synthesis, Sintering Behavior, Structure, and Electrical Properties of 5YSZ Electrolyte

In some applications, such as automotive oxygen sensors, 5 mol% Y2O3-stabilized zirconia (5YSZ) is generally used because its ionic conductivity and mechanical properties are excellent. In this study, fine 5YSZ powders, which contain only small aggregates with particle sizes in the 40-60 nm range, were prepared by a hydrolysis-hydrothermal method. Powder calcination behavior, ceramic sintering behavior, microstructure, and conductivity were studied. This research proved that the calcination temperature has a great influence on the size and phase composition of the powder. The sintering temperature of the 5YSZ ceramic significantly affected its final grain size and density. The results show that a powder pre-treatment temperature of 1100 degrees C and a sintering temperature of 1350 degrees C for 2 h can produce excellent 5YSZ ceramics. The grain size and microstructure of 5YSZ ceramics influence the bulk resistance, grain resistance, and grain boundary resistance; the value of grain resistance decreased and grain boundary resistance increased with increasing grain size and sintering temperature. Considering all aspects of the grain size, conductivity, density, and mechanical properties, the optimal sintering temperature was found to be 1350 degrees C. The highest value measured for conductivity was about 2.79 x 10(-3) S/cm, measured at 700 degrees C.