Nanostructured ceramics and oxides have been of great interest because of their potential technological applications. For example, nanocrystalline SiC (nc-SiC) has been widely applied in high-temperature structural and electronic components, nanocrystalline oxides finds a great application in thermal management device. However, the application of nc-SiC has been severely limited by its poor fracture toughness, and the performance of nanostructured oxides employed in thermal management device also needs to be further improved due to its limited thermal conductivity. Fortunately, experimental results showed that the properties of nanostructured ceramics could be engineered through optimizing the chemical composition and microstructure of grain boundaries (GBs). The conventional nc-SiC was significantly toughened by incorporating aluminium, boron, carbon, or the rare-earth oxide (Y2O3) additions into the GBs (figures as shown above). Nevertheless, such a GB engineering approach, i.e., optimizing the chemical composition and microstructure of GBs in nanostructured ceramics for desired properties, is still at a "trial and error" stage up to date.
