可调位错克服铁电氧化物中机械功能性权衡
Tunable dislocations overcome mechano-functional tradeoff in perovskite oxides
AI总结：
研究通过调控位错密度，在铁电氧化物中实现机械性能与功能性的平衡，揭示了位错密度依赖的非单调机械响应及热导率与机械强度的权衡。
摘要：
最近在位错工程方面的进展正在重塑传统观点，即陶瓷材料易碎。本文利用KTaO3（KTO），一种新发现的在室温下具有 bulk 塑性 的 铁电氧化物，证明了 seeded 位错 可有效调节机械和功能性质。我们揭示了一种新型的 brittle-ductile-brittle (BDB) 转变：低位错密度导致脆性断裂，中等密度（~10*14 m-2）使材料具有超过20%的高延展性，而高密度（~10*15 m-2）再次导致脆性断裂。这种位错密度依赖的非单调机械响应挑战了传统陶瓷行为，并提供了新的设计机会。此外，位错密度可单调降低热导率，揭示了机械强度与功能性的权衡。研究结果揭示了位错密度临界值在优化功能氧化物性能中的关键作用，并提供了一种利用位错设计先进材料的新框架，其中机械耐久性与增强功能相互交织。
英文摘要：
Recent advancements in dislocation engineering are reshaping the traditional view towards ceramics being brittle. Here, we use KTaO3 (KTO), a perovskite oxide that is newly discovered with room-temperature bulk plasticity, and demonstrate that the seeded dislocations can effectively tune both mechanical and functional properties. We uncover a novel brittle-ductile-brittle (BDB) transition: low dislocation densities lead to brittle failure, intermediate densities (~10*14 m-2) enable superior ductility with strains over 20%, and high dislocation densities (~10*15 m-2) induce again brittle fracture. This dislocation density-dependent non-monotonic mechanical response challenges the traditional behavior of ceramics and offers new design opportunities. Furthermore, dislocation densities can monotonically decrease thermal conductivity, revealing a tradeoff between mechanical strength and functionality. The findings reveal a critical threshold of dislocation density in optimizing the performance of functional oxides, and provide a new framework for using dislocations to design advanced materials where mechanical durability and enhanced functionality are intertwined.
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