Shaping single crystalline BaTiO3 nanostructures by focused neon or helium ion milling.

The realization of perovskite oxide nanostructures with controlled shape and dimensions remains a challenge. Here, we investigate the use of helium and neon focused ion beam (FIB) milling in an ion microscope to fabricate BaTiO3 nanopillars of sub-500 nm diameter from BaTiO3 (001) single crystals. Irradiation of BaTiO3 with He ions induces the formation of nanobubbles inside the material eventually leading to surface swelling and blistering. Ne FIB is shown to be suitable for milling without inducing surface swelling. The resulting defect-free single crystal nanostructures are enveloped by a neon-rich amorphous and a point defect-rich crystalline layers both on top and lateral sides. The amorphous shell can be selectively removed by dipping the nanostructures in diluted HF. The geometry and beam-induced damage of the milled nanostructures depend strongly on the patterning parameters and can be well controlled. Ne ion milling is shown to be an effective method to rapidly prototype BaTiO3 crystalline nanostructures.