Design of localized quantum structures in high temperature ceramics

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This study aims to design localized quantum structures suitable for improving mechanical properties of structural ceramics for high-temperature use. For this purpose, we investigated the effects of a small amount of dopants on mechanical properties in structural ceramics. Samples were prepared by ordinary sintering methods. As for doping, we tried to dope several kinds of ions at a level of a few one-tenth mol % using solutions including ions. In order to reveal such effects due to doping, we combined microstructual analysis at an atomic scale and mechanical properties testing. As for microstructual analysis, high resolution electron transmission microscopy (HRTEM), energy dispersive spectroscopy(EDS) and electron energy loss spectroscopy(EELS) were carried out. It was found that the dopant effect is very sensitive to mechanical properties. In particular, by doping different ions simultaneaouly, elongation at high-temperature was largely increased up to 1000% in ZrO2-based superplastic material. Such co-doping effect was confirmed to occur even at a level of 0.1mol%. This result is the first one in the field of superplastic materials. The co-doping effects could be confirmed to be due to a change of electronic structure localized at grain boundaries, which is caused by a small amount of dopants.