Resolving intrinsic dislocation structure in perovskite crystals using pulsed electron beam with atomic resolution.

Abstract

Plasticity is critical for processing semiconductors and ceramics and advancing flexible, deformable electronics. Perovskites like CsPbX₃ (X = Cl, Br, I) and SrTiO₃ exhibit remarkable room-temperature plasticity through {110} < 1<math xmlns="http://www.w3.org/1998/Math/MathML"><mover><mrow><mi>1</mi></mrow><mo>¯</mo></mover></math>0> dislocations, yet their atomic structures remain unresolved. While theoretical models predict mobile, glide-dissociated dislocations, scanning transmission electron microscopy (STEM) observations often reveal sessile, climb-dissociated structures, inconsistent with their plasticity and high-temperature climb requirements. Here, employing electrostatic dose modulator (EDM)-based pulsed electron beams that maintain the original sub-angstrom resolution, we successfully resolved intrinsic, glide-dissociated dislocations in perovskites at atomic level. The beam-off intervals allow beam-induced point defects to recombine, thereby truncating the sustained period of peak defect concentrations. Switching to continuous beams instead triggers glide-to-climb transitions, where the climbed structures depend on core chemistry: anion-terminated dislocations form compact structures, while cation-terminated ones are extended. These findings elucidate the intrinsic dislocation structures and deformation mechanisms in perovskites, offering insights to other semiconductors/ceramics show similar climb-dissociation, like Al₂O₃. The EDM-based pulsed beam technique enables non-destructive, atomic-scale observation of beam-sensitive materials, also establishes a versatile platform for active nanostructure modulation, holding great potential for semiconductor defect engineering.