Atomic-scale mapping and quantification of local Ruddlesden-Popper phase variations

Abstract

The Ruddlesden-Popper ($A_{n+1}{B}_n{\text{O}}_{3n+1}$) compounds are a highly tunable class of materials whose functional properties can be dramatically impacted by their structural phase $n$. The negligible energetic differences associated with forming a sample with a single value of $n$ versus a mixture of $n$ makes the growth of these materials difficult to control and can lead to local atomic-scale structural variation arising from small stoichiometric deviations. In this work, 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 in a statistically rigorous manner. We employ phase analysis on the 002 Bragg peak to identify horizontal Ruddlesden-Popper faults which appear as regions of high positive compressive strain within the lattice image, allowing us to quantify the local structure. Our semi-automated technique offers statistical advantages by considering effects of finite projection thickness, limited fields of view, and precise sampling rates. This method retains the real-space distribution of layer variations allowing for a spatial mapping of local $n$-phases, enabling both quantification of intergrowth occurrence as well as qualitative description of their distribution, opening the door to new insights and levels of control over a range of layered materials.

8 pages, 5 figures

References in corpus (2)

• Synthesis and electronic properties of Nd${}_{n+1}$Ni${}_n$O${}_{3n+1}$ Ruddlesden-Popper nickelate thin films
• Sr${}_2$IrO${}_4$/Sr${}_3$Ir${}_2$O${}_7$ superlattice for a model 2D quantum Heisenberg antiferromagnet

Cited by in corpus (3)

• Limits to the strain engineering of layered square-planar nickelate thin films
• A rutile-based homologous series Na(PtO${}_2$)${}_{2n+1}$ discovered by computationally assisted high-pressure synthesis
• Superconducting phase diagram of multi-layer square-planar nickelates