The Ruddlesden-Popper (KNiF) type phase LaNiOF was prepared via a polymer-based fluorination of LaNiO. The compound was found to crystallize in the orthorhombic space group Cccm ( a = 12.8350(4) Å, b = 5.7935(2) Å, c = 5.4864(2) Å). This structural distortion results from an ordered half occupation of the interstitial anion layers and has not been observed previously for KNiF-type oxyfluoride compounds. From a combination of neutron and X-ray powder diffraction and F magic-angle spinning NMR spectroscopy, it was found that the fluoride ions are only located on the apical anion sites, whereas the oxide ions are located on the interstitial sites. This ordering results in a weakening of the magnetic Ni-F-F-Ni superexchange interactions between the perovskite layers and a reduction of the antiferromagnetic ordering temperature to 49 K. Below 30 K, a small ferromagnetic component was found, which may be the result of a magnetic canting within the antiferromagnetic arrangement and will be the subject of a future low-temperature neutron diffraction study. Additionally, density functional theory-based calculations were performed to further investigate different anion ordering scenarios.

Composite electrolytes comprising a polymer plus Li salt matrix and embedded fillers have the potential of realizing high lithium-ion conductivity, good mechanical properties, wide electrochemical operational window, and stability against metallic lithium, all of which are essential for the development of high-energy-density all-solid-state lithium-ion batteries. In this study, a solvent-free approach has been used to prepare composite electrolytes with tetragonal and cubic phase garnets synthesized via nebulized spray pyrolysis with polyethylene oxide (PEO) being the polymer component. Electrochemical impedance spectroscopy (EIS) is used to examine a series of composites with different garnets and weight fractions. The results show that with the increase in the ceramic weight fraction in the composites, ionic conductivity is reduced and alternative Li-ion transport pathways become accessible for composites as compared to the filler-free electrolytes. An attempt is made to understand the ion transport mechanism within the composites. The role of the chemical and morphological properties of the ceramic filler in polymer-rich and ceramic-rich composite electrolytes is explained by studying the blends of nonconducting ceramics with the Li-conducting polymer, indicating that the intrinsic conductivity of the ceramic filler significantly contributes to the overall conductive process in the ceramic-rich systems. Further, the stability of the garnet/PEO interface is studied via X-ray photoelectron spectroscopy, and its impact on the lithium-ion transport is studied using EIS.

Electrical tuning of materials' magnetic properties is of great technological interest, and in particular reversible on/off switching of ferromagnetism can enable various new applications. Reversible magnetization tuning in the ferromagnetic Ruddlesden–Popper manganite La2−2xSr1+2xMn2O7 by electrochemical fluoride‐ion (de)intercalation in an all‐solid‐state system is demonstrated for the first time. A 67% change in relative magnetization is observed with a low operating potential of <1 V, negligible capacity fading, and high Coulombic efficiency. This system offers a high magnetoelectric voltage coefficient, indicating high energy efficiency. This method can also be extended to tune other materials' properties in various perovskite‐related materials.

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