2022, Hensling, Felix V. E., Smeaton, Michelle A., Show, Veronica, Azizie, Kathy, Barone, Matthew R., Kourkoutis, Lena F., Schlom, Darrell G.

We demonstrate the epitaxial growth of the first two members, and the n = ∞ member of the homologous Ruddlesden-Popper series of Ba n + 1 In n O 2.5 n + 1 of which the n = 1 member was previously unknown. The films were grown by suboxide molecular-beam epitaxy where the indium is provided by a molecular beam of indium-suboxide [In 2O (g)]. To facilitate ex situ characterization of the highly hygroscopic barium indate films, a capping layer of amorphous SiO 2 was deposited prior to air exposure. The structural quality of the films was assessed by x-ray diffraction, reflective high-energy electron diffraction, and scanning transmission electron microscopy.

2022, Fleck, Erin E., Barone, Matthew R., Nair, Hari P., Schreiber, Nathaniel J., Dawley, Natalie M., Schlom, Darrell G., Goodge, Berit H., Kourkoutis, Lena F.

The Ruddlesden-Popper (An+1BnO3n+1) compounds are highly tunable materials whose functional properties can be dramatically impacted by their structural phase n. The negligible differences in formation energies for different n can produce local structural variations arising from small stoichiometric deviations. Here, we present a Python analysis platform to detect, measure, and quantify the presence of different n-phases based on atomic-resolution scanning transmission electron microscopy (STEM) images. We employ image phase analysis to identify horizontal Ruddlesden-Popper faults within the lattice images and quantify the local structure. Our semiautomated technique considers effects of finite projection thickness, limited fields of view, and lateral sampling rates. This method retains real-space distribution of layer variations allowing for spatial mapping of local n-phases to enable quantification of intergrowth occurrence and qualitative description of their distribution suitable for a wide range of layered materials.