Patterning oxide nanopillars at the atomic scale by phase transformation

The team, led by Prof. Yuichi Ikuhara, applied the focused electron beam of a scanning transmission electron microscope (STEM) to irradiate SrNbO₃.4 crystals, and demonstrated a precise control of a phase transformation from layered SrNbO₃.4 to perovskite SrNbO₃ at the atomic scale.

Such a precise control of phase transformations opens up new avenues for materials design and processing, as well as advanced nanodevice fabrication. Full results of the study have been published in Nano Letters.

Phase transformations in crystalline materials are of primary fundamental interest and practical significance in a wide range of fields, including materials science, information storage and geological science. To date, it remains highly desirable to precisely tailor the phase transformations in a material due to their potential impact on macroscopic properties and thus many advanced applications.

Despite decades of efforts, precisely controlling phase transformations at the atomic scale still poses a significant challenge due to the intricacies of governing thermodynamic conditions with atomic precision. Recent technical advances in aberration-corrected STEM offer fertile new ground for probing samples by a focused sub-Angström electron beam, opening an avenue for precisely triggering phase transformations.

This work has demonstrated a successful control of a phase transformation from the layered SrNbO₃.4 to the perovskite SrNbO₃ with atomic precision by manipulating a focused sub-Angström electron beam to any selectable region.

Such a concept -- of a precise control of phase transformations with an atomic spatial precision -- should be, in principle, applicable not only to SrNbO₃.4/SrNbO₃ but also to other materials, finding applications in material processing and nanodevice fabrication.

Key points :

• Precisely controlling phase transformation with high spatial precision
• Patterning oxide nanopillars at the atomic scale by phase transformation