Aging Effect of 8 mol % YSZ Ceramics with Different Microstructures
Aging effect of dense 8 mol % yttria-stabilized zirconia (8YSZ) ceramics with different microstructures has been studied. Spark-plasma sintered (SPS) ceramics consisting of submicrometer grains showed relatively slow conductivity degradation with aging time compared with conventionally sintered ceramics. Conductivity degradation was attributed to the increase in the bulk resistivity, which would be due to subtle structural changes in the 8YSZ unit cells. SPS ceramics consisted of relatively small crystallites, which might be responsible for the relatively slow conductivity degradation.
The study of the structural transition in nanoscale materials is of particular interest for their potential applications. In the present study, we have observed a lower temperature T = 250??C for the phase transition from the sphalerite structure to the wurtzite structure in ZnS nanoparticles under a pressure of 1?GPa, as compared to those, T = 400 and 1020??C, for ZnS nanoparticles and bulk ZnS under normal pressure, respectively. The reduced transition temperature is attributed to the applied pressure leading to tight particle?particle contacts, which change the surface (or interfacial) environment of the nanoparticles and thus their surface (or interfacial) energy.