Atomic-scale description of tensile-induced desintering and formation of monatomic wires in nanostructured ceramics

We employ in situ high-resolution transmission electron microscopy (HRTEM) to observe desintering between ZrO₂ nanoparticles at room temperature with unprecedented spatial and temporal resolutions. At the atomic scale, contrary to macroscopic descriptions, no instability is observed. Instead, a stable nano-bridge (with a single grain boundary) is formed, then evolving to an ionic atomic wire. To our knowledge, this is the first observation of an ionic monatomic wire. Density-functional theory (DFT) calculations reveal the key role of oxygen vacancies in the stability and rupture of such wires. Our work provides insights on both the rupture of ceramic materials and on atomic-level control of densification processes.