In Situ Observation of Zirconia Particles at 1200°C by High‐Resolution Electron Microscopy

Zirconia (ZrO ₂ ) particles (average diameter, 30 nm) were observed in an in situ heating experiment up to 1200°C using a 400‐kV high‐resolution electron microscope. Thermal vibration of atoms on a (001) surface plane was observed at 1100°C. At 1200°C, grain growth and sintering phenomena were recorded on a videotape, showing (100) lattice planes migrating on a surface of a particle. Direct observation of the sintering process on a lattice level was accomplished for the first time.