Three-Dimensional Insights into Interfacial Segregation at the Atomic Scale in a Nanocrystalline Glass-Ceramic

The distribution of dopant atoms plays a key role in the effectiveness of doping, thereby requiring delicate characterizations. In this study, we found that energy-dispersive X-ray spectroscopy (EDX) and electron energy loss spectroscopy (EELS) techniques in scanning transmission electron microscopy (STEM) were not adequate to reveal the distribution of yttrium and the chemical composition of the ZrO₂/SiO₂ heterophase interface in an yttrium-doped ZrO₂-SiO₂ nanocrystalline glass-ceramic. Atom probe tomography (APT) is rarely utilized to characterize ceramics due to some inherent difficulties. However, we successfully revealed the three-dimensional distribution of ZrO₂ nanocrystallites and SiO₂ matrix at the atomic scale with APT under optimized and well-controlled conditions. We also found that the ZrO₂ nanocrystallites had a special core-shell structure, with a thin Zr/Si interfacial layer as a shell and a ZrO₂ solid solution as a core. Yttrium dopants showed interfacial segregation at both ZrO₂ grain boundaries and the ZrO₂/SiO₂ heterophase interfaces.