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Exploring the controllable aspects of local atomic structure and chemical ordering and their correlations with functional properties is crucial for harnessing the potential of complex oxides in the development of advanced materials. In this work, we have investigated the sensitivity of the magnetic properties in a nanostructured metastable spinel compositionally complex oxide (CCO) composition, (Mg0.2⁢Mn0.2⁢Fe0.2⁢Cu0.2⁢Zn0.2)⁢Co2⁢O4, to local chemical segregation and phase evolution introduced through variation in post-processing heat treatment temperature. A combination of x-ray diffraction, scanning transmission electron microscopy with energy dispersive x-ray spectroscopy, first-order reversal curve (FORC) magnetometry, and neutron diffraction and total scattering analyses was employed to understand both average and local structure-property evolution. Structure analysis shows that the postannealing process triggers local and long-range cation diffusion, resulting in changes in the distribution of atoms residing on the tetrahedral and octahedral sites of the spinel structure as well as nanoscale chemical heterogeneity. FORC analysis shows that redistribution of magnetic cations induces subtle magnetic phase separation and soft to hard magnetic phase transformations, and demonstrates incipient demixing of the as-synthesized material well before detection by neutron total scattering. This work additionally highlights the necessity of a combination of advanced characterization techniques for understanding the broader crystal-chemical class of compositionally complex oxides. 

The high-entropy concept was applied to synthesize a set of rare-earth perovskites REBO3 (RE = La, Pr, Nd, Sm, Eu, Gd) with the B-site occupied by Sc, Al, Cr, Ni, and Fe in equimolar ratios. All samples crystallize in the orthorhombic Pnma space group. Using an extended set of characterization measurements, the effects of multi-component material design and rare-earth selection on the electronic properties are explored. Transport measurements show semiconducting behavior. PrBO3, SmBO3, and LaBO3 show low-temperature magnetic ordering, with the ordering temperature shifting with the moment on the A-site. 

Abstract Designing highly active and robust catalysts for the oxygen evolution reaction is key to improving the overall efficiency of the water splitting reaction. It has been previously demonstrated that evaporation induced self‐assembly (EISA) can be used to synthesize highly porous and high surface area cerate‐based fluorite nanocatalysts, and that substitution of Ce with 50% rare earth (RE) cations significantly improves electrocatalyst activity. Herein, the defect structure of the best performing nanocatalyst in the series are further explored, Nd₂Ce₂O₇, with a combination of neutron diffraction and neutron pair distribution function analysis. It is found that Nd^{3 +}cation substitution for Ce in the CeO₂fluorite lattice introduces higher levels of oxygen Frenkel defects and induces a partially reduced RE_1.5Ce_1.5O_{5 +x}phase with oxygen vacancy ordering. Significantly, it is demonstrated that the concentration of oxygen Frenkel defects and improved electrocatalytic activity can be further enhanced by increasing the compositional complexity (number of RE cations involved) in the substitution. The resulting novel compositionally‐complex fluorite– (La_0.2Pr_0.2Nd_0.2Tb_0.2Dy_0.2)₂Ce₂O₇is shown to display a low OER overpotential of 210 mV at a current density of 10 mAcm⁻²in 1M KOH, and excellent cycling stability. It is suggested that increasing the compositional complexity of fluorite nanocatalysts expands the ability to tailor catalyst design. 

Mapping genetic interactions is essential for determining gene function and defining novel biological pathways. We report a simple to use CRISPR interference (CRISPRi) based platform, compatible with Fluorescence Activated Cell Sorting (FACS)-based reporter screens, to query epistatic relationships at scale. This is enabled by a flexible dual-sgRNA library design that allows for the simultaneous delivery and selection of a fixed sgRNA and a second randomized guide, comprised of a genome-wide library, with a single transduction. We use this approach to identify epistatic relationships for a defined biological pathway, showing both increased sensitivity and specificity than traditional growth screening approaches. 

Polar nanoregions (PNRs) are believed to play a decisive role in the local and macroscopic polarization in relaxor ferroelectrics. The limited microscopic understanding of the structure and dynamics of PNRs hampers the rational design of new lead-free materials. Here, the local structure of A-site disordered Bi 0.5 K 0.5 TiO 3 (BKT) is investigated using synchrotron x-ray and neutron pair distribution function (PDF) analysis and density functional theory (DFT) optimized special quasirandom structures (SQSs). DFT-relaxed SQS with a 4 × 4 × 4 supercell size can reproduce the experimental PDFs of disordered BKT, as well as the partial PDFs and total polarization, with comparable results to those reported from a combined analysis of x-ray and neutron PDF data with large-box reverse Monte Carlo methods. We find that small Bi 3+ -rich polar clusters are likely to be the microscopic origin of relaxor behavior in disordered BKT, and that the existence of large polar nanoregions (PNRs) is not necessary to explain the relaxor properties. Our results also highlight the great potential of the SQS approach to gain a nanoscale-to-microscopic understanding of other relaxor solid solutions.