Tunable dislocations overcome mechano-functional tradeoff in perovskite oxides.
basic_science · Level V
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- Record sourced from PubMed, PMID 42566535.
- Also identified by DOI 10.1126/sciadv.aed0057.
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Abstract
Recent advancements in dislocation engineering are reshaping the traditional view towards ceramics being brittle. Here, we use KTaO<sub>3</sub> (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 brittle-ductile-brittle (BDB) transition: low dislocation densities lead to brittle failure, intermediate densities (∼10<sup>14</sup> m<sup>-2</sup>) enable superior compression plastic deformation capacity with strains over 20%, and high dislocation densities (∼10<sup>15</sup> m<sup>-2</sup>) induce brittle fracture again. This dislocation density-dependent non-monotonic mechanical response challenges the traditional behavior of ceramics and offers 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 framework for using dislocations to design advanced materials where mechanical durability and enhanced functionality are intertwined.