Densification of dense nano crystalline zinc oxide under electric field

The retention of nanocrystallinity in dense ceramics is still a challenge, even with the application of stress-assisted methods like Spark Plasma Sintering. The effect of bound water combined with high heating rates seems to significantly promote the densification of zinc oxide nanoparticles. Hence, dense nano-grained ZnO could be synthesized at a temperature of only 400 °C with minimal grain growth. Microstructural analysis as well as chemical and spectroscopic methods can help identify the mechanisms involved in this peculiar behavior. The direct effect of electric field seems to be in these conditions negligible. Nevertheless, the sintering behavior can be also modified by the use of higher external electric fields. The current flow through the specimen entails an increment of the temperature produced by Joule heating, enhancing the sintering process