Room temperature ZnO ageing after Cold Sintering Process: Grain boundaries evolution characterization by in situ electrochemical impedance spectroscopy

The use of in situ characterization techniques is detrimental for the development of low temperature sintering techniques such as the Cold Sintering Process. This is particularly interesting for the investigation of interface regions, thus for grain boundaries. In the present work we focus on the evolution at room temperature, after the cold sintering of two ZnO ceramics sintered at 200 and 250 C-degrees, and show the influence of the presence of remaining acetates on the final properties. Based on in situ impedance measurements at room temperature, the present results highlight the importance of paying attention to the behavior of cold sintered samples and their evolution after sintering, due to the potential presence of even small amounts (<1 wt%) of remaining liquid species that may strongly alter the final properties of the specimen, with almost 2 orders of magnitude resistivity increase.