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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

Homologous series are layered phases that can have a range of stoichiometries depending on an index n. Examples of perovskite-related homologous series include (ABO3)nAO Ruddlesden–Popper phases and (Bi2O2) (An−1BnO3n+1) Aurivillius phases. It is challenging to precisely control n because other members of the homologous series have similar stoichiometry and a phase with the desired n is degenerate in energy with syntactic intergrowths among similar n values; this challenge is amplified as n increases. To improve the ability to synthesize a targeted phase with precise control of the atomic layering, we apply the x-ray diffraction (XRD) approach developed for superlattices of III–V semiconductors to measure minute deviations from the ideal structure so that they can be quantitatively eradicated in subsequent films. We demonstrate the precision of this approach by improving the growth of known Ruddlesden–Popper phases and ultimately, by synthesizing an unprecedented n = 20 Ruddlesden–Popper phase, (ATiO3)20AO where the A-site occupancy is Ba0.6Sr0.4. We demonstrate the generality of this method by applying it to Aurivillius phases and the Bi2Sr2Can–1CunO2n+4 series of high-temperature superconducting phases.

Treating septic arthritis of the hip with coexisting advanced degenerative disease is challenging. The use of primary total hip arthroplasty (THA) has led to postoperative infection rates as high as 22%. Insertion of antibiotic spacers with subsequent reimplantation of a THA controls infection and improves pain and function in patients with periprosthetic infections.We asked whether two-stage exchange for patients with degenerative joint disease (DJD) and coexisting septic arthritis would control infection and improve pain relief and function both during the period after insertion of the spacer and after conversion to THA.We retrospectively reviewed 14 patients with severe DJD and either active or recent septic arthritis treated with débridement and insertion of a primary antibiotic-loaded cement spacer between 1996 and 2008. Ten patients underwent subsequent exchange to a permanent hip arthroplasty. Four patients did not undergo exchange to a permanent THA: two died from unrelated causes and two elected not to proceed with exchange because their spacer provided adequate function. We obtained a modified Harris hip score. The minimum clinical followup was 7 months (average, 28 months; range, 7-65 months) after insertion of the spacer.Mean pain scores improved from 6 to 34, and overall Harris hip scores improved from 11 to 67 at last followup with the spacer. Those who underwent definitive THA had further improvement in their mean Harris hip scores to 93.Articulating antibiotic spacers offer acceptable pain relief and function while the infection is treated in this unique group of patients.Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.