The present paper will show how primary crystallites can be used as building blocks for homogenous packing and rapid sintering. Namely, the ordered agglomeration of zirconia primary crystallites into secondary particle assemblies ensured their homogeneous packing,[1] while also preserving the high surface energy to higher temperatures, increasing the sintering activity. When exposed to intense electromagnetic radiation, activated by the SPS set-up in a static graphite crucible, providing rapid heating at 250 °C/min, the assembled crystallites were subjected to further agglomeration, coalescence and sliding, leading to rapid densification in the absence of extensive diffusional processes, cancelling out the grain growth during the initial and intermediate sintering stages. As a result, zirconia nanoceramic was obtained after only 2 minutes at 1300 °C.[2] The observed mechanisms of crystallite coalescence and rearrangement during the rapid heating could shed more light on the densification and grain-growth mechanisms operating in other rapid-sintering methods. 

[1] A. Kocjan, Z. Shen, Colloidal processing and partial sintering of high-performance porous zirconia nanoceramics with hierarchical heterogeneities. J. Eur. Ceram. Soc. 2013, 33, 3165–3176. 

[2] A. Kocjan, M. Logar, Z. Shen, The agglomeration, coalescence and sliding of nanoparticles, leading to the rapid sintering of zirconia nanoceramics. Sci. Rep. 2017, 7, 1–8.