Bonding relay for room-temperature oxide plasticity like metals

TL;DR

This paper demonstrates that certain oxides can exhibit room-temperature plasticity through a bonding relay mechanism enabled by specific layered charge structures, challenging the traditional view of oxides as brittle materials.

Contribution

It introduces a universal structural criterion for oxide plasticity based on charge layering, revealing a new pathway for metal-like ductility in oxides.

Findings

Oxides like SrTiO3 and MgO can be plastically deformed at room temperature.

A structural criterion involving alternating charged layers enables oxide plasticity.

Bonding relay mechanism mimics metallic bonding to facilitate dislocation motion.

Abstract

Oxides have long been regarded as intrinsically brittle due to their strong, directional ionic or covalent bonds, in stark contrast to the ductile behavior of metals, where delocalized electron sharing enables plasticity through facile dislocation glide. Here, we challenge this paradigm by demonstrating that typical oxides, such as SrTiO3 and MgO, can exhibit room-temperature plasticity with pronounced crystallographic anisotropy. Through an integrated approach combining ab initio calculations, large scale molecular dynamics simulations, and experimental nanoindentation, we identify a universal structural criterion enabling room-temperature oxide plasticity: the presence of alternating positively and negatively charged atomic layers along specific slip directions, specifically the (1-10)[110] orientation in perovskite and rocksalt oxides. This charge alternating configuration enables a bonding relay mechanism, in which sequential bond breaking and reformation across the slip plane accompanied by interlayer persistent bonds mimics multi centered interactions in metals, thereby facilitating dislocation motion without catastrophic failure. Our findings reveal a previously unrecognized pathway to achieving metal-like plasticity in oxides and establish a structural design principle for engineering flexible and mechanically resilient oxide materials.