Analog control of La0.5Sr0.5FeO3 delta electrical properties through oxygen deficiency induced magnetic transition

Switchability of materials properties by applying controlled stimuli such as voltage pulses is an emerging field of study with applicability in adaptive and programmable devices like neuromorphic transistors or non emissive smart displays. One of the most exciting approaches to modulate materials performance is mobile ion vacancy insertion for inducing changes in relevant electrical, optical, or magnetic properties, among others. Unveiling the interplay between changes in the concentration of mobile defects like oxygen vacancies and functional properties in relevant materials represents a step forward for underpinning the emerging oxide iontronics discipline. In this work, electrochemical oxide ion solid state pumping cells were fabricated for analog control of the oxygen stoichiometry in thin films of mixed ionic electronic conductor La0.5Sr0.5FeO3 amp; 948;. We demonstrate over more than four orders of magnitude electronic conductivity control at 50 amp; 8201; C within the same crystallographic phase through precise and continuous voltage control of the oxygen stoichiometry. We show that behind the modification of the transport properties of the material lays a paramagnetic to antiferromagnetic transition. We exploit such magnetoelectric coupling to show control over the exchange interaction between La0.5Sr0.5FeO3 amp; 948; and a ferromagnetic Co layer deposited on to

Two stage evolution of magnetic correlations in the spiral spin liquid material Ca10Cr7O28

We present an X band and tunable high frequency high field electron spin resonance HF ESR study of single crystalline Ca10Cr7O28, which constitutes alternating antiferromagnetic and ferromagnetic kagome bilayers. At high temperatures, a phonon assisted relaxation process is evoked to account for the pronounced increase of the linewidth in an exchange narrowing regime kBT gt; gt; J . In contrast, at low temperatures kBT lt; J , a power law behavior in line narrowing is observed. Our data reveal two distinct power law regimes for the linewidth which crossover at T amp; 8727; amp; 8776; 7.5K. Notably, the intriguing evolution of the ESR linewidth in this alternating kagome bilayer system with opposite sign of exchange interactions highlights distinct spin dynamics compared to those in a uniform kagome antiferromagne

Prediction of Olivine Composition Under Limited Calibration Inputs Comparative Study of Mid Infrared Reflection, Raman Scattering, and Laser Induced Plasma Spectroscopies

In situ optical analytical spectroscopies offer great geochemical insights due to their capability to resolve the chemical composition of regolith surfaces of rocky celestial bodies. The use of suitable calibration targets improves the precision of mineral determination, which is of critical importance for short living, low mobility landers, and enables, in special cases, determination of elemental composition. We investigate the capabilities of three space relevant optical analytical techniques used for in situ mineralogical analysis, i.e., mid infrared reflection, Raman light scattering, and laser induced plasma spectroscopies, to predict the chemical composition of olivine under a limited calibration input, namely using two bulk samples of natural olivine, chemically close to the end members of the mineral group. We determine the accuracy of the forsterite numbers obtained with each technique and discuss the choice of calibration methods applicable to limited in situ calibration input, which are summarized in recommendations for space instrumentatio

Processing of AlSi13Mg5 foams using Mg and AlMg50 blowing agents

Aluminium closed cell foams with superior structure and properties can be produced using Mg based blowing agents. In this study, AlSi13Mg5 foams were produced via the powder metallurgy route using two different Mg based blowing agents pure Mg powders and pre alloyed AlMg50 powders. Mass spectrometry was performed to determine their hydrogen desorption characteristics. In Mg powder, the peak gas release occurred at 364 C compared to the delayed peak gas release at 420 C from AlMg50 powder. The structure and properties of the foams produced using these two blowing agents were compared by performing image analysis and compression tests, respectively. On average, the foams produced using AlMg50 blowing agents exhibited slightly better porous structure and strength. Peak strength of the foams produced using Mg and AlMg50 powder is 7.3 0.6 MPa and 8 0.4 MPa, respectivel

Field driven spin structure evolution in MnCr2S4 A high field single crystal neutron diffraction study

We present a comprehensive microscopic insight into the spin configurations within the bond frustrated cubic spinel compound MnCr2 amp; 8290;S4 directly unveiled through extensive single crystal neutron diffraction studies carried out in zero magnetic field and in fields up to 35 T. While our zero field results confirm the ferrimagnetic structure with an antiparallel arrangement of the magnetic Cr3 and Mn2 sublattices below amp; 119879;FiM amp; 8776;65 K, as well as the presence of the exotic Yafet Kittel phase below amp; 119879;YK amp; 8776;5 K, our data measured in fields enable us to precisely determine the field induced magnetic structures and their evolution across the phase transitions at amp; 120583;0 amp; 8290; amp; 119867;1 amp; 8776;11T and amp; 120583;0 amp; 8290; amp; 119867;2 amp; 8776;25T and beyond that towards amp; 120583;0 amp; 8290; amp; 119867;3 amp; 8776;50T . Additionally, combining our experimental findings with mean field theory calculations reveals a complex field dependence of the Mn Mn and Mn Cr exchange interactions across the different phases, highlighting the significant influence of spin lattice coupling in this materia

Dynamic magnetic ground state in the dimer based compound Yb2Te5O13

We report the discovery of a dynamic magnetic ground state in the Yb3 dimer based compound Yb2 amp; 8290;Te5 amp; 8290;O13 through various characterization techniques down to sub Kelvin temperatures. Magnetization measurements reveal the absence of long range magnetic ordering down to 0.4 K and the onset of magnetic correlations below 1 K. Heat capacity data, measured down to 0.37 K, indicate a small finite energy gap in zero field, amp; 916; amp; 8289; 0 amp; 8764; 0.55 K, and validate the presence of magnetic correlations with a Kramers doublet ground state amp; 119869;eff 1 2 . Further insight is provided by zero field muon spin relaxation amp; 120583; amp; 8290;SR measurements, which show a gradual slowdown of Yb3 spin fluctuations below 30 K, indicating a dynamic state down to 44 mK. The temperature dependence of the relaxation rate, amp; 120582;, confirms the presence of the Orbach process, which is mediated through various crystal electric field levels, complementing the amp; 119869;eff 1 2 ground state. Furthermore, longitudinal field amp; 120583; amp; 8290;SR measurements performed at 70 mK demonstrate that the Yb3 spins remain dynamic even under an external field of 3200 Oe, with fluctuations becoming stronger with increasing magnetic field. Theoretical investigations further support the dynamic state, revealing competition between intra and interdimer exchange interactions as the underlying cause. By integrating macroscopic and microscopic measurements with theoretical insights, we propose Yb2 amp; 8290;Te5 amp; 8290;O13 as a quantum spin liquid candidate, opening avenues for research in quantum magnetis

REMINISCE Refurbishment of Mirrors to Increase Sustainability at Light Sources

Contamination or damage to X ray optics is becoming increasingly problematic for beamlines at 3rd and 4th generation storage rings and FEL sources. Carbon contamination, induced by ultra intense photon beams, can cause a major loss in flux, focusing power, and specific absorptions which are detrimental to spectroscopy. For new light sources, with higher coherence, intensity, and repetition rates, contamination and accumulated damage will occur more rapidly. Replacing damaged optics is a time consuming, risky, and expensive task. Production times are typically gt;6 months, and sometimes exceed 1 year. Costs per optic are typically tens of thousands of Euro, and can exceed 100k Euro. If several optics need to be replaced on a beamline, the overall cost can be hundreds of thousands of Euros. It is not sustainable or cost effective to replace optics on a yearly basis. Most facilities have independently investigated optical contamination over many years, but coordinated action is now required before the problem gets out of control. These issues motivate two fold action find practical methods to slow down the rate of contamination and damage; and develop protocols to safely remove contamination and return the optic to a pristine condition. High quality metrology and surface science techniques are required to quantify the topography and chemical nature of the contamination, and assess the effectiveness of methods to reduce or remove it. To achieve these challenging goals requires a community effort. We propose an extensive collaboration, including experts from a range of scientific disciplines at various synchrotron and XFEL labs. X ray optic community projects have recently delivered improvements in the quality X ray mirrors via enhanced optical metrology. It is hoped that a concerted group effort will deliver similar major advancements, thereby helping to provide beamlines with cleaner, better performing, X ray optic

X ray absorption spectrum of O2

The x ray absorption spectrum of the O 2 molecular cation is measured. The ions are stored in a cryogenically cooled radiofrequency ion trap and probed by tunable synchrotron radiation. The spectrum exhibits several salient features a three state composite amp; 120587; resonance at the low energy side followed by a two component exchange split, a highly dissociative, amp; 120590; resonance pulled down well below the ionization limit; and a complex valence Rydberg high energy part, including several resolved bands. Small structures are interpreted as correlation state satellites with leading internal or semi internal configurations. Calculations using the restricted active space wave functions and quantum wave packet dynamics offer an overall excellent interpretation of the spectral feature

Multimodal Operando Analysis of Lithium Sulfur Multilayer Pouch Cells An In Depth Investigation on Cell Component Design and Performance

This study presents an innovative operando analysis of lithium sulfur Li S multilayer pouch cells, employing a combination of lab source and synchrotron x ray imaging to investigate sulfur crystallite dissolution and lithium dendrite formation. By integrating advanced X ray imaging, impedance spectroscopy, and simultaneous monitoring of temperature and pressure, the research uncovers critical insights into the behavior of active and inactive cell components. The analysis reveals significant degradation increments, primarily driven by side product accumulation and the deterioration of lithium microstructures, which contribute to performance loss over cycling. Additionally, temperature distribution analysis shows a strong correlation between joule heating, polarization resistance, and the observed endothermic processes during crystallization. These findings provide a comprehensive understanding of the mechanistic processes within industrially relevant pouch cells, highlighting opportunities for optimizing Li S cell designs and advancing high energy density battery systems for commercial application

Extrinsic and Intrinsic Factors Governing the Electrochemical Oxidation of Propylene in Aqueous Solutions

The electrochemical synthesis of commodity chemicals such as epoxides and glycols offers a sustainable alternative to conventional methods that involve hazardous chemicals. Efforts to improve the yield and selectivity of propylene oxidation using Pd based catalysts have been shown to be highly sensitive to applied potential, pH, and electrochemical cell design. Record efficiencies and yields were obtained by substitution of PdO by 4d or 5d transition metals, including Pt, with thus far little rationale regarding the origin for the improvement. Through electrochemical analysis, scanning transmission electron microscopy, X ray absorption spectroscopy, and surface enhanced infrared absorption spectroscopy, we investigated the mechanism of propylene oxidation on Pd based catalysts. We demonstrate that adsorbates forming on PdO, where Pd adopts a square planar coordination [PdO4], differ from that forming on the surface of oxidized metallic Pd catalysts with an oxo intermediate mediating propylene oxidation on PdO. We further show that Pt substitution in PdO does not modify this oxo intermediate. Varying pH, we found that the onset for propylene oxidation is pH independent, indicating a potential determining step where the proton is not involved in and similar reaction pathway in acidic and near neutral conditions. Finally, our work undoubtedly demonstrates that high Faradaic efficiency toward propylene glycol and propylene oxide formation, such as those previously reported in the literature, can be achieved by means of electrode engineering and mastery of mass transport and local pH. Notably, we achieved amp; 8776;100 faradaic efficiency for propylene glycol at 1.7 V vs RHE in acidic media using a Pt substituted PdO catalyst loaded onto a gas diffusion electrod