Patterning Oxide Nanopillars at the Atomic Scale by Phase Transformation

Phase transformations in crystalline
materials are common in nature and often modify dramatically properties
of materials. The ability to precisely control them with a high spatial
precision represents a significant step forward in realizing new functionalities
in confined dimensions. However, such control is extremely challenging
particularly at the atomic scale due to the intricacies in governing
thermodynamic conditions with a high spatial accuracy. Here, we apply
focused electron beam of a scanning transmission electron microscope
to irradiate SrNbO3.4 crystals and demonstrate a precise
control of a phase transformation from layered SrNbO3.4 to perovskite SrNbO3 at the atomic scale. By purposely
squeezing O atoms out of the vertex-sharing NbO6 octahedral
slabs, their neighboring slabs zip together, resulting in a patterning
of SrNbO3 nanopillars in SrNbO3.4 matrix. Such
phase transformations can be spatially manipulated with an atomic
precision, opening up a novel avenue for materials design and processing
and also for advanced nanodevice fabrication.