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Correction Publisher s Note Long range superconducting proximity effect in YBa2Cu3O7 La0.7Ca0.3MnO3 weak link arrays
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Monitoring the state of charge of vanadium redox flow batteries with an EPR on a Chip dipstick sensor
Get PDFThe vanadium redox flow battery VRFB is considered a promising candidate for large scale energy storage in the transition from fossil fuels to renewable energy sources. VRFBs store energy by electrochemical reactions of different electroactive species dissolved in electrolyte solutions. The redox couples of VRFBs are VO2 VO2 and V2 V3 , the ratio of which to the total vanadium content determines the state of charge SOC . V IV and V II are paramagnetic half integer spin species detectable and quantifiable with electron paramagnetic resonance spectroscopy EPR . Common commercial EPR spectrometers, however, employ microwave cavity resonators which necessitate the use of large electromagnets, limiting their application to dedicated laboratories. For an SOC monitoring device for VRFBs, a small, cost effective submersible EPR spectrometer, preferably with a permanent magnet, is desirable. The EPR on a Chip EPRoC spectrometer miniaturises the complete EPR spectrometer onto a single microchip by utilising the coil of a voltage controlled oscillator as both microwave source and detector. It is capable of sweeping the frequency while the magnetic field is held constant enabling the use of small permanent magnets. This drastically reduces the experimental complexity of EPR. Hence, the EPRoC fulfils the requirements for an SOC sensor. We, therefore, evaluate the potential for utilisation of an EPRoC dipstick spectrometer as an operando and continuously online monitor for the SOC of VRFBs. Herein, we present quantitative proof of principle submersible EPRoC experiments on variably charged vanadium electrolyte solutions. EPR data obtained with a commercial EPR spectrometer are in good agreement with the EPRoC dat
The impact of interfacial quality and nanoscale performance disorder on the stability of alloyed perovskite solar cells
Get PDFMicroscopy provides a proxy for assessing the operation of perovskite solar cells, yet most works in the literature have focused on bare perovskite thin films, missing charge transport and recombination losses present in full devices. Here we demonstrate a multimodal operando microscopy toolkit to measure and spatially correlate nanoscale charge transport losses, recombination losses and chemical composition. By applying this toolkit to the same scan areas of state of the art, alloyed perovskite cells before and after extended operation, we show that devices with the highest macroscopic performance have the lowest initial performance spatial heterogeneity a crucial link that is missed in conventional microscopy. We show that engineering stable interfaces is critical to achieving robust devices. Once the interfaces are stabilized, we show that compositional engineering to homogenize charge extraction and to minimize variations in local power conversion efficiency is critical to improve performance and stability. We find that in our device space, perovskites can tolerate spatial disorder in chemistry, but not charge extractio
Correction Orbital selective effect of spin reorientation on the Dirac fermions in a non charge ordered kagome ferromagnet Fe3Ge
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Controlling effective field contributions to laser induced magnetization precession by heterostructure design
Get PDFNanoscale heterostructure design can control laser induced heat dissipation and strain propagation, as well as their efficiency for driving magnetization precession. Here, we incorporate MgO layers into the experimental platform of metallic Pt Cu Ni heterostructures to block the propagation of hot electrons. We show via ultrafast x ray diffraction the capability of our platform to control the spatio temporal shape of the transient heat and strain. Time resolved magneto optical Kerr experiments with systematic tuning of the magnetization precession frequency showcase control of the magnetization dynamics in the Ni layer. Our experimental analysis highlights the role of quasi static strain as a driver of precession when the magnetic material is rapidly heated via electrons. The effective magnetic field change originating from demagnetization partially compensates the change induced by quasi static strain. The strain pulses can be shaped via the nanoscale heterostructure design to efficiently drive the precession, paving the way for opto magneto acoustic devices with low heat energy deposited in the magnetic laye
Deep understanding of LiCoO2 electrode degradation for optimized recycling strategies
No full textEmpowered by a synergistic combination approach of Scanning Transmission X ray Microscopy STXM imaging and X ray Absorption Near Edge Structure XANES spectroscopy, a quantitative analysis on the composition and spatial distribution of the cathode in a failed 18650 LiCoO2 LCO battery was conducted. Distinct compositional differences between the central and peripheral cathode regions in the failed LCO battery were discerned by utilizing bulk XANES in Total Electron Yield TEY and Fluorescence Yield FY modes. The central region shows more severe degradation in terms of LCO reduction and excess cathode electrolyte interface CEI buildup. Meanwhile, the STXM technique precisely imaged a specific region of interest in the center of the cathode, covering C, O, and F K edges, and Co L2,3 edge, to deeply investigate the degradation. Quantitative chemical mapping with spatially resolved XANES spectroscopy, facilitate an in depth understating of the interfacial reactions on battery electrodes and battery failure fundamental
Electrically induced cancellation and inversion of piezoelectricity in ferroelectric Hf0.5Zr0.5O2
Get PDFHfO2 based thin films hold huge promise for integrated devices as they show full compatibility with semiconductor technologies and robust ferroelectric properties at nanometer scale. While their polarization switching behavior has been widely investigated, their electromechanical response received much less attention so far. Here, we demonstrate that piezoelectricity in Hf0.5Zr0.5O2 ferroelectric capacitors is not an invariable property but, in fact, can be intrinsically changed by electrical field cycling. Hf0.5Zr0.5O2 capacitors subjected to ac cycling undergo a continuous transition from a positive effective piezoelectric coefficient d33 in the pristine state to a fully inverted negative d33 state, while, in parallel, the polarization monotonically increases. Not only can the sign of d33 be uniformly inverted in the whole capacitor volume, but also, with proper ac training, the net effective piezoresponse can be nullified while the polarization is kept fully switchable. Moreover, the local piezoresponse force microscopy signal also gradually goes through the zero value upon ac cycling. Density functional theory calculations suggest that the observed behavior is a result of a structural transformation from a weakly developed polar orthorhombic phase towards a well developed polar orthorhombic phase. The calculations also suggest the possible occurrence of a non piezoelectric ferroelectric Hf0.5Zr0.5O2. Our experimental findings create an unprecedented potential for tuning the electromechanical functionality of ferroelectric HfO2 based device
Beyond Conventional Carbon Activation Creating Porosity without Etching Using Cesium Effect
Get PDFFacile synthesis of porous carbon with high yield and high specific surface area SSA from low cost molecular precursors offers promising opportunities for their industrial applications. However, conventional activation methods using potassium and sodium hydroxides or carbonates suffer from low yields lt;20 and poor control over porosity and composition especially when high SSAs are targeted gt;2000 m2 g amp; 8722;1 because nanopores are typically created by etching. Herein, a non etching activation strategy is demonstrated using cesium salts of low cost carboxylic acids as the sole precursor in producing porous carbons with yields of up to 25 and SSAs reaching 3008 m2 g amp; 8722;1. The pore size and oxygen content can be adjusted by tuning the synthesis temperature or changing the molecular precursor. Mechanistic investigation unravels the non classical role of cesium as an activating agent. The cesium compounds that form in situ, including carbonates, oxides, and metallic cesium, have extremely low work function enabling electron injection into organic carbonaceous framework, promoting condensation, and intercalation of cesium ions into graphitic stacks forming slit pores. The resulting porous carbons deliver a high capacity of 252 mAh g amp; 8722;1 567 F g amp; 8722;1 and durability of 100 000 cycles as cathodes of Zn ion capacitors, showing their potential for electrochemical energy storag
35 challenges in materials science being tackled by PIs under 35 ish in 2024
No full textHere, we highlight 35 global researchers approximately under the age of 35. This third annual cohort was self generated by initial seed invitations sent by the editorial team, with each contributor suggesting two more in a nominally supervised self selecting pyramid like scheme. The final collection reflects both the diversity and excitement across the field of materials scienc
What doesn amp;apos;t fit is made to fit Pim 1 kinase adapts to the configuration of stilbene based inhibitors
No full textRecently, we have developed novel Pim 1 kinase inhibitors starting from a dihydrobenzofuran core structure using a computational approach. Here, we report the design and synthesis of stilbene based Pim 1 kinase inhibitors obtained by formal elimination of the dihydrofuran ring. These inhibitors of the first design cycle, which were obtained as inseparable cis trans mixtures, showed affinities in the low single digit micromolar range. To be able to further optimize these compounds in a structure based fashion, we determined the X ray structures of the protein ligand complexes. Surprisingly, only the cis isomer binds upon crystallization of the cis trans mixture of the ligands with Pim 1 kinase and the substrate PIMTIDE, the binding mode being largely consistent with that predicted by docking. After crystallization of the exclusively trans configured derivatives, a markedly different binding mode for the inhibitor and a concomitant rearrangement of the glycine rich loop is observed, resulting in the ligand being deeply buried in the binding pocke