Nanoscale stacking fault-assisted room temperature plasticity in flash-sintered TiO₂

Ceramics are commonly used for structural purposes due to their high strength and thermal stability. However, their brittleness limits their deformation at low temperatures. Traditional ceramics fracture before plastic deformation occurs because dislocations are difficult to nucleate. Prior research has shown that dislocation activity is rare in ceramics, requiring high stress to initiate plasticity. This limitation has hindered the use of ceramics in applications needing ductility. The flash-sintering process has emerged as a novel method to alter ceramic properties. This gap motivated investigations into whether flash-sintering could enhance room temperature plasticity in ceramics. No prior work had resolved how nanoscale defects might influence deformation in TiO₂. This paper explores the deformation behavior of TiO₂ produced via flash-sintering.

The goal was to examine the deformation behavior of TiO₂ produced using flash-sintering. The specific problem addressed is the lack of plasticity in ceramics at low temperatures. Flash-sintering introduces high-density defects and oxygen vacancies, which may influence deformation mechanisms. The researchers aimed to determine if these defects could enable plasticity at room temperature. They also wanted to compare deformation behaviors at different temperatures. The motivation stems from the need for ceramics with enhanced ductility. This work could inform new approaches to ceramic processing. The study focuses on TiO₂ as a model ceramic material.

The study used flash-sintering to prepare TiO₂ samples. In situ compression tests were conducted to observe deformation at room temperature and 600°C. Microstructural analysis focused on stacking faults and nanotwins. High-resolution imaging techniques captured defect formation during deformation. Oxygen vacancy concentrations were measured using electron microscopy. The researchers compared deformation responses across temperature ranges. They analyzed how preexisting defects influenced plasticity. The methods combined mechanical testing with microstructural characterization.

Flash-sintered TiO₂ showed ~10% strain at room temperature without cracking. Stacking faults and nanotwins formed during compression. These defects may be linked to oxygen vacancies and preexisting defects. Deformation behavior varied with testing temperature. Room temperature deformation was dominated by stacking fault formation. At 600°C, different mechanisms emerged. The material retained plasticity without brittle failure. The results suggest flash-sintering alters deformation pathways in ceramics.

The authors propose that nanoscale stacking faults and nanotwins enable room temperature plasticity in flash-sintered TiO₂. These features may arise from oxygen vacancies and preexisting defects. The deformation behavior changes with temperature. The findings suggest flash-sintering can modify ceramic ductility. The study supports the idea that defect engineering influences plasticity. The results do not confirm a single mechanism but suggest multiple pathways. The authors suggest further investigation into defect-assisted deformation. The implications are limited to the specific material and processing method used.