The retention of nanocrystallinity in dense ceramics is still a challenge, even with the application of stress-assisted methods like Spark Plasma Sintering. Starting powder and sintering process strongly affect the evolution of the microstructure and thus, the final properties of ZnO. Control of the microstructure was carried out through the combined effect of high heating rates and the presence of bound water, which seems to significantly promote densification of zinc oxide nanoparticles. Hence, dense nano-grained ZnO could be synthesized at a temperature of only 400 °C. In addition, sintering behavior can be also modified by the use of external electric fields, which can generate a drastic mass diffusion process that is called flash sintering. The current flow through the specimen entails an increment of the temperature produced by Joule heating, enhancing the sintering process. Control of both parameters, heating rates/water content and electric field, leads to dense ZnO compacts with grain size between 150 nm to almost 5 μm.

Date Published: 8 March 2014
PDF: 7 pages
Proc. SPIE 8987, Oxide-based Materials and Devices V, 89871H (8 March 2014); doi: 10.1117/12.2042872

Published in SPIE Proceedings Vol. 8987:
Oxide-based Materials and Devices V
Ferechteh H. Teherani; David C. Look; David J. Rogers, Editor(s)