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The National Synchrotron Radiation Research Center (NSRRC) is bracing for the next phase of its second accelerator project, Taiwan Photon Source (TPS), once the civil construction is completed in 2013, marking a successful example of having dual adjacent rings, with one under construction while the other is in operation. The transformation of the synchrotron-based light source by adding the TPS to the existing Taiwan Light Source (TLS) has the mission of providing Taiwan's scientific community and high-tech industry with needed facilities and resources for them to stay ahead in technological competition, using brilliant synchrotron light sources from infrared, VUV, and soft X-ray to hard X-ray. [ABSTRACT FROM PUBLISHER]

Reversible solid oxide cells (rSOCs) have significant potential as efficient energy conversion and storage systems. Nevertheless, the practical application of their conventional air electrodes, such as La0.8Sr0.2MnO3−δ (LSM), Ba0.5Sr0.5Co0.8Fe0.2O3‐δ (BSCF), and PrBa0.8Ca0.2Co2O5+δ (PBCC), remains unsatisfactory due to interface delamination during prolonged electrochemical operation. Using micro‐focusing X‐ray absorption spectroscopy (µ‐XAS), a decrease (increase) in the co‐valence state from the electrode surface to the electrode/electrolyte interface is observed, leading to the above delamination. Utilizing the one‐pot method to incorporate an oxygen‐vacancy‐enriched CeO2 electrode into these air electrodes, the uniform distribution of the Co valence state is observed, alleviating the structural delamination. PBCC–CeO2 electrodes exhibited a degradation rate of 0.095 mV h−1 at 650 °C during a nearly 500‐h test as compared with 0.907 mV h−1 observed during the 135‐h test for PBCC. Additionally, a remarkable increase in electrolysis current density from 636 to 934 mA cm−2 under 1.3 V and a maximum power density from 912 to 989 mW cm−2 upon incorporating CeO2 into PBCC is also observed. BSCF–CeO2 and LSM–CeO2 also show enhanced electrochemical performance and prolonged stability as compared to BSCF and LSM. This work offers a strategy to mitigate the structural delamination of conventional electrodes to boost the performance of rSOCs. [ABSTRACT FROM AUTHOR]

Li‐rich Mn‐based layered oxides (LLO) hold great promise as cathode materials for lithium‐ion batteries (LIBs) due to their unique oxygen redox (OR) chemistry, which enables additional capacity. However, the LLOs face challenges related to the instability of their OR process due to the weak transition metal (TM)‐oxygen bond, leading to oxygen loss and irreversible phase transition that results in severe capacity and voltage decay. Herein, a synergistic electronic regulation strategy of surface and interior structures to enhance oxygen stability is proposed. In the interior of the materials, the local electrons around TM and O atoms may be delocalized by surrounding Mo atoms, facilitating the formation of stronger TM─O bonds at high voltages. Besides, on the surface, the highly reactive O atoms with lone pairs of electrons are passivated by additional TM atoms, which provides a more stable TM─O framework. Hence, this strategy stabilizes the oxygen and hinders TM migration, which enhances the reversibility in structural evolution, leading to increased capacity and voltage retention. This work presents an efficient approach to enhance the performance of LLOs through surface‐to‐interior electronic structure modulation, while also contributing to a deeper understanding of their redox reaction. [ABSTRACT FROM AUTHOR]

Developing cathode materials with high performance in oxygen reduction reaction (ORR) is desirable for proton ceramic fuel cells (PCFCs) for energy conversion technology. BaCo0.4Fe0.4Zr0.1Y0.1O3–δ (BCFZY) is widely investigated as a cathode. Herein, BCFZY cathode is used as a paradigmatic example to study the impact of calcination temperature on microstructure, electronic structure, and ORR performance. Ion beam‐scanning electron microscopy indicates BCFZY prepared at 800 °C (BCFZY800) exhibits the largest specific surface area and cathode/electrolyte contact area. BCFZY800 exhibits a peak power density of 1.32 W cm−2 at 650 °C, which is 37% and 193% higher than that of BCFZY prepared at 700 °C (BCFZY700) and 1100 °C (BCFZY1100), respectively. Furthermore, BCFZY800 demonstrates high long‐term stability over 500 h. Soft X‐Ray absorption spectra indicate that the oxidation state of BCFZY800 is reduced, suggesting more catalytically active sites than those of BCFZY700 and BCFZY1100 after the ORR. This work provides a new understanding for enhanced PCFCs performance by proper porosity structure via fine‐tuning the calcination temperature. [ABSTRACT FROM AUTHOR]

On the last day of 2014, the newly completed second accelerator of the National Synchrotron Radiation Research Center (NSRRC), Taiwan Photon Source (TPS), delivered its first synchrotron light in the early afternoon. The electron beam energy of the TPS circulating in the storage ring has reached the design value of 3 GeV, and the stored beam current has achieved over 5 mA, marking a significant milestone for Taiwan's new synchrotron light source. After nearly five years of construction and development efforts in full scale, the successful commissioning of TPS will forever change the course of scientific research in Taiwan. [ABSTRACT FROM AUTHOR]

The electronic structure of the semiconductor Ba2CoO4 has been investigated using x‐ray absorption spectroscopy at the Co‐L2,3 and O‐K edges as well as soft x‐ray valence band photoemission. The spectra can be accurately reproduced by a combination of full atomic‐multiplet configuration‐interaction cluster calculations and ab‐initio band structure analysis. The large negative O 2p to Co 3d charge‐transfer energy has been established as well as the high stability of the S=5/2 high‐spin state of the Co4+ ion. The band gap of this high‐oxidation state material is sizeable and can be attributed to the joint effect of electron correlations, the local tetrahedral coordination of the Co ions, and the poor electronic connection between the CoO4 tetrahedra. [ABSTRACT FROM AUTHOR]

Lithium difluoro(oxalato) borate (LiDFOB) has been widely investigated in lithium‐ion batteries (LIBs) owing to its advantageous thermal stability and excellent aluminum passivation property. However, LiDFOB tends to suffer from severe decomposition and generate a lot of gas species (e.g. CO2). Herein, a novel cyano‐functionalized lithium borate salt, namely lithium difluoro(1,2‐dihydroxyethane‐1,1,2,2‐tetracarbonitrile) borate (LiDFTCB), is innovatively synthesized as a highly oxidative‐resistant salt to alleviate above dilemma. It is revealed that the LiDFTCB‐based electrolyte enables LiCoO2/graphite cells with superior capacity retention at both room and elevated temperatures (e.g. 80 % after 600 cycles) with barely any CO2 gas evolution. Systematic studies reveal that LiDFTCB tends to form thin and robust interfacial layers at both electrodes. This work emphasizes the crucial role of cyano‐functionalized anions in improving cycle lifespan and safety of practical LIBs. [ABSTRACT FROM AUTHOR]

Lithium difluoro(oxalato) borate (LiDFOB) has been widely investigated in lithium‐ion batteries (LIBs) owing to its advantageous thermal stability and excellent aluminum passivation property. However, LiDFOB tends to suffer from severe decomposition and generate a lot of gas species (e.g. CO2). Herein, a novel cyano‐functionalized lithium borate salt, namely lithium difluoro(1,2‐dihydroxyethane‐1,1,2,2‐tetracarbonitrile) borate (LiDFTCB), is innovatively synthesized as a highly oxidative‐resistant salt to alleviate above dilemma. It is revealed that the LiDFTCB‐based electrolyte enables LiCoO2/graphite cells with superior capacity retention at both room and elevated temperatures (e.g. 80 % after 600 cycles) with barely any CO2 gas evolution. Systematic studies reveal that LiDFTCB tends to form thin and robust interfacial layers at both electrodes. This work emphasizes the crucial role of cyano‐functionalized anions in improving cycle lifespan and safety of practical LIBs. [ABSTRACT FROM AUTHOR]

Oxygen‐ion conducting perovskite oxides are important functional materials for solid oxide fuel cells and oxygen‐permeable membranes operating at high temperatures (>500 °C). Co‐doped perovskites have recently shown their potential to boost oxygen‐related kinetics, but challenges remain in understanding the underlying mechanisms. This study unveils the local cation arrangement as a new key factor controlling oxygen kinetics in perovskite oxides. By single‐ and co‐doping Nb5+ and Ta5+ into SrCoO3‐δ, dominant factors affecting oxygen kinetics, such as lattice geometry, cobalt states, and oxygen vacancies, which are confirmed by neutron and synchrotron X‐ray diffraction as well as high‐temperature X‐ray absorption spectroscopy, are controlled. The combined experimental and theoretical study unveils that co‐doping likely leads to higher cation dispersion at the B‐site compared to single‐doping. Consequently, a high‐entropy configuration enhances oxygen ion migration in the lattice, translating to improved oxygen reduction activity. [ABSTRACT FROM AUTHOR]

Urea oxidation reaction (UOR) with a low equilibrium potential offers a promising route to replace the oxygen evolution reaction for energy‐saving hydrogen generation. However, the overpotential of the UOR is still high due to the complicated 6e− transfer process and adsorption/desorption of intermediate products. Herein, utilizing a cation exchange strategy, Ni‐doped CuO nanoarrays grown on 3D Cu foam are synthesized. Notably, Ni‐CuO NAs/CF requires a low potential of 1.366 V versus a reversible hydrogen electrode to drive a current density of 100 mA cm−2, outperforming various benchmark electrocatalysts and maintaining robust stability in alkaline media. Theoretical and experimental studies reveal that Ni as the driving force center can effectively enhance the urea adsorption and stabilize CO*/NH* intermediates toward the UOR. These findings suggest a new direction for constructing nanostructures and modulating electronic structures, ultimately developing promising Cu‐based electrode catalysts. [ABSTRACT FROM AUTHOR]

Corner‐sharing and edge‐sharing networks are the two most important material genomes. Inspired by the efficient electron transport capacity of corner‐sharing structures and the low steric hindrance of edge‐sharing units, an attempt is made to exert both merits by combining these two networks. Here, a unique self‐assembled hybrid SrCo0.55Fe0.5O3‐δ nanorod composed of a corner‐sharing SrCo0.5Fe0.5O3‐δ phase and edge‐sharing Co3O4 structure is synthesized through a Co‐site enrichment method, which exhibits the low overpotentials of 310 and 290 mV at 10 mA cm–2 for oxygen‐evolving reaction in 0.1 m and 1.0 m KOH, respectively. This efficiency is attributed to the high Co valence with strong CoO covalence and the short distance between CoCo/Fe metal active sites in hybrid nanorods, realizing a synergistic benefit. Combined multiple operando/ex situ characterizations and computational studies show that the edge‐sharing units in hybrid nanorods can help facilitate the deprotonation step of lattice oxygen mechanism (LOM) while the corner‐sharing motifs can accelerate the electron transport during LOM processes, triggering an unusual lattice‐oxygen activation. This methodology of combining important material structural genomes can offer meaningful insights and guidance for various catalytic applications. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) is a key half-reaction in many electrochemical transformations, and efficient electrocatalysts are critical to improve its kinetics which is typically sluggish due to its multielectron-transfer nature. Perovskite oxides are a popular category of OER catalysts, while their activity remains insufficient under the conventional adsorbate evolution reaction scheme where scaling relations limit activity enhancement. The lattice oxygen-mediated mechanism (LOM) has been recently reported to overcome such scaling relations and boost the OER catalysis over several doped perovskite catalysts. However, direct evidence supporting the LOM participation is still very little because the doping strategy applied would introduce additional active sites that may mask the real reaction mechanism. Herein, a dopant-free, cation deficiency manipulation strategy to tailor the bulk diffusion properties of perovskites without affecting their surface properties is reported, providing a perfect platform for studying the contribution of LOM to OER catalysis. Further optimizing the A-site deficiency achieves a perovskite candidate with excellent intrinsic OER activity, which also demonstrates outstanding performance in rechargeable Zn-air batteries and water electrolyzers. These findings not only corroborate the key role of LOM in OER electrocatalysis, but also provide an effective way for the rational design of better catalyst materials for clean energy technologies. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) is a vital electrochemical process for various energy conversion and fuel production technologies. Co/Ni‐rich perovskite oxides are extensively studied as promising alternatives to precious‐metal catalysts; however, low‐cost and earth‐abundant iron (Fe)‐rich perovskites are rarely investigated to date due to their poor activity and durability. This study reports an Fe‐rich Sr0.95Ce0.05Fe0.9Ni0.1O3−δ (SCFN) perovskite oxide with minor Ce/Ni co‐doping in A/B sites as a high‐performance OER electrocatalyst. Impressively, SCFN shows more than an order of magnitude enhancement in mass‐specific activity compared to the SrFeO3−δ (SF) parent oxide, and delivers an attractive small overpotential of 340 mV at 10 mA cm−2, outperforming many Co/Ni‐rich perovskite oxides ever reported. Additionally, SCFN displays robust operational durability with negligible activity loss under alkaline OER conditions. The increased activity and stability of SCFN can be ascribed to co‐doping‐induced synergistic promotion between structural and electronic modulation, where Ce doping facilitates the formation of a 3D corner‐sharing cubic structure and Ni doping gives rise to strong electronic interactions between active sites, which is key to achieving a highly active long‐life catalyst. Importantly, this strategy is universal and can be extended to other Fe‐based parent perovskite oxides with high structural diversity. [ABSTRACT FROM AUTHOR]

An effective strategy using d -block metal hybridization was proposed to induce electronic interaction and promote the synergistic effect, aiming to enhance the OER performance of cost-effective spinel LiMn 2 O 4. Indeed, we deployed a series of LiNi x Mn 2- x O 4 catalysts substituted with Ni, yielding the increase of Mn valence states from Mn3.5+ to Mn4+. The LiNi 0.5 Mn 1.5 O 4 catalyst achieved an excellent OER performance in alkaline media, with an overpotential reduction more than 320 mV at 10 mA cm−2 compared to the unsubstituted LiMn 2 O 4 , as well as the electrochemical stability. It was shown to be superior to the most reported Mn-based oxides OER electrocatalysts. Theoretical calculations demonstrated that Ni doped holes in the Mn site, leading to an increase in Mn4+, and that the shared covalent network of Ni 3 d -O 2 p -Mn 3 d optimized an easier desorption of intermediates. These results pave a new example for modulating the chemisorption strength, thus enabling activating the activity and stability of OER process for cost-effective electrocatalysts based on spinel Mn oxides. [Display omitted] • The d -block metal hybridization induced the synergistic effect in LiNi 0.5 Mn 1.5 O 4. • The site-to-site electron transfer was enhanced through the Ni-O-Mn network. • The adsorption energy of intermediates was optimized, yielding the improved activity and stability towards OER. [ABSTRACT FROM AUTHOR]

This article, titled "Key Roles of Initial Calcination Temperature in Accelerating the Performance in Proton Ceramic Fuel Cells via Regulating 3D Microstructure and Electronic Structure," explores the impact of different initial calcination temperatures on the performance of BaCo0.4Fe0.4Zr0.1Y0.1O3‐δ (BCFZY) powder in fuel cells. The authors discuss how the microstructure and electronic structure of the BCFZY800 cathode contribute to its superior electrochemical performance. The article provides valuable insights into the optimization of fuel cell performance through the manipulation of calcination temperatures. [Extracted from the article]

Identifying real active sites and understanding the mechanism of oxygen evolution reaction (OER) are still a big challenge today for developing efficient electrochemical catalysts in renewable energy technologies. Here, using a combined in situ/operando experiments and theory, the catalytic mechanism of the ordered OER active Co and Ir ions in Sr2CoIrO6−δ is studied, which exhibits an unprecedented low overpotential 210 mV to achieve 10 mA cm–2, ranking the highest performance among perovskite‐based solid‐state catalysts. Operando X‐ray absorption spectroscopies as a function of applied voltage indicates that Ir4+ ion is gradually converted into extremely high‐valence Ir5+/6+, while the part of Co3+ ion is transferred into Co4+ under OER process. Density functional theory calculations explicitly reveal the order Co‐O‐Ir network as an origin of ultrahigh OER activity. The work opens a promising path to overcome the sluggish kinetics of OER bottleneck for water splitting via proper arrangements of the multi‐active sites in catalyst. [ABSTRACT FROM AUTHOR]

Confusion has arisen about the Co spin‐state transition under high pressure for multiferroic BiCoO3. The crystal structure analysis indicates a high‐spin (HS) to low‐spin (LS) state transition with increasing pressure, while Co Kβ X‐ray emission spectra present a high‐spin to intermediate‐spin (IS) state transition. Herein, the spin state of Co3+ in BiCoO3 is investigated utilizing soft X‐ray absorption spectroscopy (XAS) at the Co‐L2,3 and O‐K edges at room temperature under ambient pressure. Furthermore, the spin state transition of Co3+ under high pressure is investigated by Co Kβ X‐ray emission spectra. A pure HS‐Co3+ ground state is found in the BiCoO3 sample prepared from the precursor and oxidizer mixed method—and the existence of a small part of LS‐Co3+ in the BiCoO3 sample prepared from the precursor and oxidizer sandwiched method. A complete HS‐Co3+ to LS‐Co3+ transition is observed under high pressure up to 32.3 GPa. The results clarify the debate on the spin‐state transition of BiCoO3 under high pressure and will deepen our understanding of the intrinsic physical properties on it. [ABSTRACT FROM AUTHOR]

An A-site ordered but B-site disordered quadruple perovskite oxide PbMn3Cr3MnO12 was synthesized by high-pressure and high-temperature methods. The compound crystallizes in space group Im-3 with the charge distribution of Pb2+Mn3+3Cr3+3Mn4+O12. Three antiferromagnetic phase transitions are found to occur at TN1 ≈ 155, TN2 ≈ 81, and TN3 ≈ 74 K, respectively, due to the complex B-site and A′-B intersite spin interactions. Compared with the isostructural LaMn3Cr4O12 with negligible A′-B intersite spin coupling, the substitution of Mn4+, which has identical electronic configuration to that of Cr3+ (t2g3), into the B site can introduce A′-B intersite spin interactions. As a result, the A′-site spin-related ordering temperature increases significantly, while the B-site one remains little changed in the current PbMn3Cr3MnO12. This work opens up a way to enhance the A′-site spin ordering temperature in quadruple perovskite oxides. [ABSTRACT FROM AUTHOR]

LiCoO2 is used as a cathode material for lithium‐ion batteries, however, cationic/anodic‐redox‐induced unstable phase transitions, oxygen escape, and side reactions with electrolytes always occur when charging LiCoO2 to voltages higher than 4.35 V, resulting in severe capacity fade. Reported here is Mg‐pillared LiCoO2. Dopant Mg ions, serving as pillars in the Li‐slab of LiCoO2, prevent slab sliding in a delithiated state, thereby suppressing unfavorable phase transitions. Moreover, the resulting Li‐Mg mixing structure at the surface of Mg‐pillared LiCoO2 is beneficial for eliminating the cathode‐electrolyte interphase overgrowth and phase transformation in the close‐to‐surface region. Mg‐pillared LiCoO2 exhibits a high capacity of 204 mAh g−1 at 0.2 C and an enhanced capacity retention of 84 % at 1.0 C over 100 cycles within the voltage window of 3.0–4.6 V. In contrast, pristine LiCoO2 has a capacity retention of 14 % within the same voltage window. [ABSTRACT FROM AUTHOR]

LiCoO2 is used as a cathode material for lithium‐ion batteries, however, cationic/anodic‐redox‐induced unstable phase transitions, oxygen escape, and side reactions with electrolytes always occur when charging LiCoO2 to voltages higher than 4.35 V, resulting in severe capacity fade. Reported here is Mg‐pillared LiCoO2. Dopant Mg ions, serving as pillars in the Li‐slab of LiCoO2, prevent slab sliding in a delithiated state, thereby suppressing unfavorable phase transitions. Moreover, the resulting Li‐Mg mixing structure at the surface of Mg‐pillared LiCoO2 is beneficial for eliminating the cathode‐electrolyte interphase overgrowth and phase transformation in the close‐to‐surface region. Mg‐pillared LiCoO2 exhibits a high capacity of 204 mAh g−1 at 0.2 C and an enhanced capacity retention of 84 % at 1.0 C over 100 cycles within the voltage window of 3.0–4.6 V. In contrast, pristine LiCoO2 has a capacity retention of 14 % within the same voltage window. [ABSTRACT FROM AUTHOR]

This study fabricated amorphous-carbon-encapsulated magnetite (Fe3O4@a-C) nanoparticles (NPs) and observed that the encapsulation significantly enhanced the room-temperature magnetization of the NPs by approximately 22.5%. Generalized gradient approximation with the Hubbard-U correction involved the ionic picture hypothesis of electron acceptors for Fe3O4, namely, e2↓t23↓ → e2↓t23↓e↑, which link the spin-polarized charge transfer to Fe ions at the tetrahedral site FeA of Fe3O4. Fe K-edge X-ray absorption near-edge structure (XANES) spectra suggested a formal charge reduction in the FeA of the Fe3O4@a-C NPs. Moreover, Fe L3-edge x-ray magnetic circular dichroism yielded the same conclusion as that obtained using the XANES spectra and suggested the restoration of an orbital moment in the Fe3O4@a-C NPs. Synchrotron radiation spectroscopy confirmed the charge reduction of FeA, which accounted for the magnetic enhancement. [ABSTRACT FROM AUTHOR]

Layered transition metal (TM) oxides have aroused enormous interest in both fundamental and applied cathode material research in the context of high energy‐density batteries. Although various mechanisms have been proposed to explain their significant initial capacity losses, the effect of the local structural defects on performance has been largely ignored. Herein, the stacking faults are visualized and their presence is correlated with the incomplete phase transition in Li2RuO3 to understand the significant abnormal capacity loss in the first cycle. The comprehensive performance evaluation, physical characterization and theoretical calculations indicate that the two types of stacking faults, the [100]//[11¯0] boundaries and the [110]//[11¯0] boundaries, lead to sluggish lithium diffusion and increasing stacking faults deteriorates the lithium insertion dynamics. These findings are helpful to understand the performance degradation of the layer‐structured oxides in which the anionic redox or the transition metal migration is not involved in electrochemical reactions. It is hoped that this research will also inspire new ideas for designing novel cathode materials and for improving the performance of existing materials by tuning the local structures or minimizing the local structural defects. [ABSTRACT FROM AUTHOR]

Replacing the anodic oxygen evolution reaction (OER) with a thermodynamically favorable ethanol oxidation reaction (EOR) is regarded as a promising approach to simultaneously realize energy‐saving H2 evolution and high‐value chemical production. Herein, the single‐atom In‐doped subnanometer Pt nanowires (SA In‐Pt NWs) as high‐performance electrocatalysts for both the hydrogen evolution reaction (HER) and EOR under universal pH conditions is designed. The SA In‐Pt NWs/C can be employed to integrate HER with EOR to avoid the large overpotential caused by sluggish OER, which requires a smaller voltage of 0.62 V to reach 10 mA cm–2 compared with that of water splitting (2.07 V). The reaction also exhibits a high faradaic efficiency of over 93% in upgrading ethanol to valuable acetate in the anodic cell. Mechanistic investigations indicate that the combination of the ultrathin 1D morphology and single‐atom In decoration provides the maximum number of active sites and effectively activates Pt atoms for catalysis. Density functional theory calculations further demonstrate that doped In can effectively promote the HER, while also promoting the conversion of ethanol to acetate. Moreover, through the use of SA In‐Pt NWs/C as electrocatalysts, many other alcohols can also be employed as anodic feedstock to achieve coupled electrolysis. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 is a promising route to convert waste products to valuable chemicals. Search for suitable and efficient CO2 reduction electrocatalysts with high C2:C1 selectivity holds great promise. Herein, for the first time we have developed a molten salt oxidized method to modify the morphology and oxidation state of a Cu‐foam catalyst. The catalyst displayed a current density of 30 mA cm−2 (−1.4 V versus reversible hydrogen electrode) and an ethylene/methane ratio of 870. We provide insight into the improved performance of the catalysts by cross section scanning transmission electron microscopy and quasi in situ soft X‐ray spectroscope, which show that copper oxides are surprisingly reconstructed with Cu (I) and Cu (0) on the surface during the reaction. First principle calculations also demonstrate that the partly reduced Cu2O (111) surface has a high reactivity and selectivity for C2+ products. Furthermore, the molten salt treated catalysts could be applied to the direct synthesis of multi‐carbon fuels, including C3‐C4 compounds in high CO2 pressure electrocatalytic reduction. Our results demonstrate that molten salt are both the oxidizing agent and reaction medium, which is a promising approach for synthesis of highly active CO2 electrocatalysts, which may open a new way for industrial application. [ABSTRACT FROM AUTHOR]

An A- and B-site ordered quadruple perovskite oxide LaCu3Co2Re2O12 was synthesized at 9 GPa and 1323 K. The compound possesses a Pn-3 space group, where both A and B sites are orderly occupied by different cations with a nearly 100% degree of order. Bond valence sum calculations and x-ray absorption spectroscopy confirm the charge distribution to be LaCu2+3Co2+2Re5.5+2O12. A ferrimagnetic phase transition is found to occur around 150 K due to the Cu2+(↑)-Co2+(↑)-Re5.5+(↓) spin coupling found by x-ray magnetic circular dichroism at Cu-, Co-, and Re-L2,3 edges. The magnetoresistance effects as well as the first-principle calculations indicate the half-metallic nature for LaCu3Co2Re2O12 with a wider energy gap at the up-spin channel and a conducting band at the down-spin channel. [ABSTRACT FROM AUTHOR]

Heteroepitaxially flexible oxide systems have been intensely developed and considered as the most promising materials for leading the creation of next‐generation flexible electronic devices. Among them, perovskite manganites have attracted significant attention with their abundant and novel properties such as colossal magnetoresistance (CMR) and metal‐insulator transition. However, the requirement of high quality samples hampers this field, not to mention the advanced nanoengineering. In this study, fluorophlogopite mica (F‐mica) is selected as a flexible substrate to fabricate heteroepitaxial Pr0.5Ca0.5MnO3 (PCMO) with a nanocolumn structure. Through a precise control of thickness, different morphologies are realized to manipulate the magnetotransport properties (reduction of melting field). Moreover, thanks to the excellent flexibility of F‐mica, mechanical modulation of CMR (≈1000%) can be achieved in different flex modes while the magnetic properties remain unaffected. Detailed bending tests are performed to study the behavior of resistive change (≈30%). Through the combination of high flexibility, high quality PCMO, and well‐designed nanocolumn structure, the study exhibits the significant controllability of CMR via mechanical bending, and manifests the potential of such a heteroepitaxially flexible oxide system which can be applied on flexible magnetoresistive devices and sensors. [ABSTRACT FROM AUTHOR]

This report investigates the phase evolution pathway of magnetite nanocrystal synthesis on oxide-supported substrates. A template-free phase separation approach, which exploits the thermodynamic instability of ternary perovskite BiFeO3 and inherent volatility of bismuth oxide in low oxygen pressure and high temperature is presented. The formation of an intermediate hematite nanocrystal phase is found as a key step that controls the eventual size and morphology of the magnetite nanocrystals. X-ray absorption spectra measurements and X-ray magnetic circular dichroism confirm that the spectral fingerprints of the magnetite nanocrystals match with that of bulk crystals. Magnetic measurements show that magnetic anisotropy is directly attributed to the nanocrystal morphology. [ABSTRACT FROM AUTHOR]

A series of Eu3+-activated strontium silicate phosphors, Sr2SiO4:xEu3+ (SSO:xEu3+, x = 1.0, 2.0 and 5.0%), were synthesized by a sol–gel method, and their crystalline structures, photoluminescence (PL) behaviors, electronic/atomic structures and bandgap properties were studied. The correlation among these characteristics was further established. X-ray powder diffraction analysis revealed the formation of mixed orthorhombic α'-SSO and monoclinic β-SSO phases of the SSO:xEu3+ phosphors. When SSO:xEu3+ phosphors are excited under ultraviolet (UV) light (λ = 250 nm, ~ 4.96 eV), they emit yellow (~ 590 nm), orange (~ 613 nm) and red (~ 652 and 703 nm) PL bands. These PL emissions typically correspond to 4f–4f electronic transitions that involve the multiple excited 5D0 → 7FJ levels (J = 1, 2, 3 and 4) of Eu3+ activators in the host matrix. This mechanism of PL in the SSO:xEu3+ phosphors is strongly related to the local electronic/atomic structures of the Eu3+–O2− associations and the bandgap of the host lattice, as verified by Sr K-edge and Eu L3-edge X-ray absorption near-edge structure (XANES)/extended X-ray absorption fine structure, O K-edge XANES and Kα X-ray emission spectroscopy. In the synthesis of SSO:xEu3+ phosphors, interstitial Eu2O3-like structures are observed in the host matrix that act as donors, providing electrons that are nonradiatively transferred from the Eu 5d and/or O 2p–Eu 4f/5d states (mostly the O 2p–Eu 5d states) to the 5D0 levels, facilitating the recombination of electrons that have transitioned from the 5D0 level to the 7FJ level in the bandgap. This mechanism is primarily responsible for the enhancement of PL emissions in the SSO:xEu3+ phosphors. This PL-related behavior indicates that SSO:xEu3+ phosphors are good light-conversion phosphor candidates for use in near-UV chips and can be very effective in UV-based light-emitting diodes. [ABSTRACT FROM AUTHOR]

Sluggish kinetics and poor reversibility of cathode chemistry is the major challenge for magnesium batteries to achieve high volumetric capacity. Introduction of the cuprous ion (Cu+) as a charge carrier can decouple the magnesiation related energy storage from the cathode electrochemistry. Cu+ is generated from a fast equilibrium between copper selenide electrode and Mg electrolyte during standing time, rather than in the electrochemical process. A reversible chemical magnesiation/de‐magnesiation can be driven by this solid/liquid equilibrium. During a typical discharge process, Cu+ is reduced to Cu and drives the equilibrium to promote the magnesiation process. The reversible Cu to Cu+ redox promotes the recharge process. This novel Cu+ mediated cathode chemistry of Mg battery leads to a high reversible areal capacity of 12.5 mAh cm−2 with high mass loading (49.1 mg cm−2) of the electrode. 80 % capacity retention can be achieved for 200 cycles after a conditioning process. [ABSTRACT FROM AUTHOR]

Sluggish kinetics and poor reversibility of cathode chemistry is the major challenge for magnesium batteries to achieve high volumetric capacity. Introduction of the cuprous ion (Cu+) as a charge carrier can decouple the magnesiation related energy storage from the cathode electrochemistry. Cu+ is generated from a fast equilibrium between copper selenide electrode and Mg electrolyte during standing time, rather than in the electrochemical process. A reversible chemical magnesiation/de‐magnesiation can be driven by this solid/liquid equilibrium. During a typical discharge process, Cu+ is reduced to Cu and drives the equilibrium to promote the magnesiation process. The reversible Cu to Cu+ redox promotes the recharge process. This novel Cu+ mediated cathode chemistry of Mg battery leads to a high reversible areal capacity of 12.5 mAh cm−2 with high mass loading (49.1 mg cm−2) of the electrode. 80 % capacity retention can be achieved for 200 cycles after a conditioning process. [ABSTRACT FROM AUTHOR]

Although stoichiometric CrTe is difficult to synthesize because of the appearance of Cr vacancies, ferromagnetic Cr1−x Te compounds have attracted increasing attention. This work investigates single crystalline (Cr0.9 B0.1)Te with the Cr vacancies filled by B to stabilize the hexagonal crystal structure and shift the Fermi energy. The structural and magnetic properties have been characterized by experimental measurements and ab initio calculations. A collinear spin structure with an easy axis along c is observed at high temperature, whereas the magnetic moments localized at the Cr atoms gradually tilt away from the c-axis below 140 K. A maximum tilt angle of 30 ° is observed at a temperature of 2 K. [ABSTRACT FROM AUTHOR]

Lithium‐rich layered oxides are promising candidate cathode materials for the Li‐ion batteries with energy densities above 300 Wh kg−1. However, issues such as the voltage hysteresis and decay hinder their commercial applications. Due to the entanglement of the transition metal (TM) migration and the anionic redox upon lithium extraction at high potentials, it is difficult to recognize the origin of these issues in conventional Li‐rich layered oxides. Herein, Li2MoO3 is chosen since prototype material to uncover the reason for the voltage hysteresis as the TM migration and anionic redox can be eliminated below 3.6 V versus Li+/Li in this material. On the basis of comprehensive investigations by neutron powder diffraction, scanning transmission electron microscopy, synchrotron X‐ray absorption spectroscopy, and density functional theory calculations, it is clarified that the ordering–disordering transformation of the Mo3O13 clusters induced by the intralayer Mo migration is responsible for the voltage hysteresis in the first cycle; the hysteresis can take place even without the anionic redox or the interlayer Mo migration. A similar suggestion is drawn for its iso‐structured Li2RuO3 (C2/c). These findings are useful for understanding of the voltage hysteresis in other complicated Li‐rich layered oxides. [ABSTRACT FROM AUTHOR]

A negative-thermal-expansion-like volume contraction in LaCu 3 Fe 4 O 12-δ was proposed to result from an inter-site charge transfer between Fe and Cu, namely from Cu3+-Fe3+ at room temperature to Cu2+-Fe3.75+ above 393 K (T C , charge-transfer temperature). Although the partial valence transition of the Fe valence state was observed by Mössbauer spectroscopy and the BVS method, there is no direct observation of the electron transfer to the Cu site in this material until now. In this work, we have studied the valence state of Cu ions in LaCu 3 Fe 4 O 12-δ as a function of temperature across T C using soft x-ray absorption spectroscopy at the Cu- L 3 and the O K edges. We indeed observed a sharp decrease in the valence state of Cu across the phase transition temperature T C. Nevertheless, Cu is 2.2 + and 2.7 + at 440 K and 80 K, respectively, indicates an incomplete inter-site charge transfer across T C. The temperature-dependence Cu- L 3 XAS spectra indicate that there is merely partial electron transfer from Fe to Cu. This is different from the proposed charge transfer from Cu3+-Fe3+ to Cu2+-Fe3.75+ since Cu is not pure 3 + at 80 K far below the phase transition temperature (T C = 393 K) and on the other hand not pure 2 + at 440 K far above T C. Image 1 [ABSTRACT FROM AUTHOR]

Abstract The electronic and magnetic structure of orthorhombic (o-) YMn 0.5 Fe 0.5 O 3 (YMFO) epitaxial film (space group Pbnm) deposited on the YAlO 3 (010) substrate have been investigated using linear polarization-dependent x-ray absorption spectroscopy and magnetization measurements. The magnetic-ordering temperature of around 280 K is observed in o -YMFO film. The x-ray absorption spectra at the Fe- K and the Mn- K edges indicate the existence of anisotropic crystal field in o -YMFO film, with the longest and shortest Fe–O and Mn–O bonds tend to align with the crystallographic b - and a -axis, respectively, whereas the medium Fe(Mn)–O bond is aligned with the c -axis. The experimental x-ray magnetic linear dichroism at the Fe- L 2 edges demonstrate an unusual single antiferromagnetic axis of Fe3+ ions below magnetic-ordering temperature, while a multi antiferromagnetic axis is generally observed in o-R FeO 3 (R = rare earth) thin films. Our configuration-interaction cluster calculations also reveal that the single antiferromagnetic axis of the Fe sublattice is aligned with the b -axis in o -YMFO film, whereas it is directed along the a -axis in the bulk o -YFeO 3. Highlights • The single antiferromagnetic axis of Fe3+ ions is observed below Néel temperature. • The cluster calculations verify that the spin of Fe3+ ions is aligned with b -axis. • The absence of spin reorientation is revealed in orthorhombic YMn 0.5 Fe 0.5 O 3 film. [ABSTRACT FROM AUTHOR]

Abstract The oxygen evolution reaction (OER) plays a crucial role in the application of water splitting, which is a highly competitive option for a sustainable energy future. Thus, it is vital to design highly active and durable electrocatalyst for OER. Herein a hybrid with the nominal composition of Ba 2 Co 1.5 Mo 0.25 Nb 0.25 O 6-δ (denoted as BC1.5 MN) electrocatalyst consisting of both double perovskite and single perovskite structures is synthesized by a solid-state reaction method. When tested as an electrocatalyst for OER, the BC1.5 MN electrocatalyst requires a current density of 10 mA cm−2 at an overpotential of 400 mV, an onset overpotential of 260 mV, and a Tafel slope of 70 mV dec−1, which are superior to that of precious metal oxide IrO 2 catalyst. Chronoamperometric and cyclic voltammetry studies demonstrate that the BC1.5 MN electrocatalyst has outstanding durability in alkaline solution. The synergistic effect between multi-active sites derived from a single/double perovskite hybrid structure results in one of the most active perovskite-based OER electrocatalysts in alkaline solution. Graphical abstract Synopsis: The synergistic effect between multi-active sites derived from a single/double perovskite hybrid structure lead to the extraordinary OER performance. Image 1 [ABSTRACT FROM AUTHOR]

Single crystals of the quaternary R‐type ferrites BaLiRu5O11 [a = 11.628(6) Å, c = 13.7596(5) Å], and BaCu1+xRu5–xO11 [a = 11.6825(6) Å, c = 13.8051(7) Å], and their quinary solid solution BaLi1–xCux+δRu5–δO11 [a = 11.6453(2) Å, c = 13.7772(3) Å] were obtained by flux growth technique. X‐ray diffraction reveals the compounds to crystallize in space group P63/m with Z = 8. Measurements of the magnetic susceptibility of BaLiRu5O11 and BaCu1+xRu5–xO11, applying Curie–Weiss fits, confirm their paramagnetic behavior with temperature independent contributions of χ0,mol = 3.27 × 10–3 cm3·mol–1 and χ0,mol = 2.47 × 10–3 cm3·mol–1, respectively. Furthermore, the valence state of Ru in BaLiRu5O11 and BaCu1+xRu5–xO11 was determined to +3.8 by X‐ray absorption spectroscopy. Cu in BaCu1+xRu5–xO11 is dominating in a +2 state according to X‐ray photoelectron and X‐ray absorption spectroscopy, while a minor amount in +1 state may represent the excess copper substituting some Ru within a distorted Kagome net arrangement. [ABSTRACT FROM AUTHOR]

Developing efficient electrocatalyst at large current densities to meet the requirement of industrial water splitting is a big challenge today. Herein, we report a class of catalyst, BiCoO 3 with pyramidally coordinated Co3+. BiCoO 3 exhibits a large current density of 1000 mA cm−2 at a low overpotential of 402 mV and the overpotential even reduces to only 303 mV to achieve 1000 mA cm−2 by replacing Co with Fe, which belongs to the first-class level among large-current-densities electrocatalysts reported so far. Different from artificially created oxygen vacancies to optimize the bonding strength of the intermediate for enhancement of OER activity, BiCoO 3 has the rich active sites and the shortest reaction pathway leading to a large current density, as structurally every Co-O cluster has one oxygen vacancy. This work opens a new avenue for enhanced OER activity at high current densities via optimizing the arrangement of ligand vacancies. [Display omitted] • The first in-depth study of BiCoO 3 perovskite with pyramidally coordinated Co3+ in the water oxidation reaction. • The OER performance of BCFO belongs to the first-class level among large-current-densities electrocatalysts reported so far. • BiCoO 3 has the rich active sites and the shortest reaction pathway leading to an extraordinary large current density. [ABSTRACT FROM AUTHOR]

To investigate the influence of chemical pressure on the eg orbital occupation and the spin state of Co3+ ions, which are closely related to electrochemical reaction of catalysts for energy storage applications, we have prepared a new material Sr1.7Ca0.3CoO3F, which was previously predicted to possess an intermediate‐spin (IS) state with eg1 configuration. Our experimental Co‐L2,3 X‐ray absorption spectrum of Sr1.7Ca0.3CoO3F was very similar to those of the high‐spin (HS) Co3+ references Sr2CoO3F and Sr2CoO3Cl indicating an HS Co3+ ground state. The HS‐Co3+ ground state in Sr1.7Ca0.3CoO3F was further confirmed by using O‐K XAS spectra and theoretical simulation of the Co‐L2,3 XAS spectra with configuration‐interaction cluster calculations. We present theoretical energy diagrams of three spin states for Co3+ ions in Sr2CoO3F as a function of external pressure based on the crystal structures observed in a previous high‐pressure study. We have also investigated the structural conditions that are required to stabilize the IS state in this effective local pyramidal structure theoretically, and found that the in‐plane Co–O distance (<1.88 Å) and the out‐of‐plane Co displacement (<0.18 Å) are critical conditions for obtaining the IS‐Co3+ ground state. [ABSTRACT FROM AUTHOR]

The exchange bias (EB) effect, which is the shift of the hysteresis loop of a ferromagnet in direct contact with an antiferromagnet, is highly advantageous for the development of spintronics applications. Carbon (C) has been considered as a potential material in next generation electronics production as well as spintronics devices beyond silicon. Here we show experimental evidence for an EB in C/Co composites. The significant EB needs thermal annealing to occur. X-ray absorption spectra and transmission electron microscopy data of these samples reveal that Co carbides in as grown samples decompose and form graphitic C/Co interfaces after annealing. Using x-ray magnetic circular dichroism we have detected the C spins that are responsible for the EB. These results inspire a theoretical model to investigate the magnetic interactions in graphitic C/Co interfaces and interpret the observed results. [ABSTRACT FROM AUTHOR]

Trim-iron-pieces and trim-coils were used to correct the magnetic field error in a superconducting undulator with a magnet period of 15 mm. The main-coils were wound with NbTi wires of 0.77 x 0.51 mm2 rectangular cross section. The entire iron pole array was electrically insulated from the main-coils using Teflon to avoid degradation of the superconducting wire when the main-coils were trained to a large current. The trim-coils were wound with NbTi wires of 0.33 mm diameter. The trim-iron-pieces and trim-coils were mounted directly on the iron pole. The electric current of these trim-coils were generated by a single power supply with a constant voltage. A variable resistor and two golden-case resistors were connected in parallel to adjust the current that passed through each trim-coil. In this work, three trim-iron-pieces and one trim-coil were fabricated and mounted on each of the upper and lower arrays, and their effect on correcting the magnetic field error of the undulator is measured and compared to a model simulation. [ABSTRACT FROM AUTHOR]

To generate synchrotron radiation with an extended photon spectral range, a new staggered undulator design capable of switching between two magnet periods is proposed. The magnetic structure of this design consists of one fixed magnet array and three movable ones located in a solenoid coil. For demonstrative purpose, two undulators with a 20/40 mm and 160/320 mm dual magnet periods, respectively, have been designed and their magnetic field and photon brilliance calculated. A superconducting solenoid coil is optimized to produce a highly uniform field over the entire undulator length. The mechanical design of the undulator is also presented. [ABSTRACT FROM AUTHOR]

• Mo-doping is responsible for an enhanced OER activity of the exsoluted catalyst Co 0.76 Fe 0.18 Mo 0.06 O 1.35. • Mo-doping enhanced the oxidation state of the exsolved Co 0.76 Fe 0.18 Mo 0.06 O 1.35 before and after OER. • The O-K SXAS spectra revealed no La ions at the surface layers, and confirmed the formation of oxyhydroxide. Developing and understanding efficient catalysts for anodic oxygen evolution reaction (OER) is critical for the electrochemical production of H 2 for energy storage and transformation. Herein, a Co 0.76 Fe 0.18 Mo 0.06 O 1.35 catalyst with a spinel structure (CFMO-800) was prepared from Mo-doped LaCo 0.8 Fe 0.2 O 3 perovskites (LCF) by a simple exsolution method. The CFMO-800 catalyst exhibited a low potential of 1.48 V (vs. RHE) at a current density of 10 mA cm−2 in 1 M KOH surpassing all spinel and perovskite Co/Fe oxide catalysts reported. The surface-sensitive soft X-ray absorption spectroscopies (SXAS) at the Co-L 2,3 and the O-K edges revealed an unexpected increase in the Co valence state of CFMO-800 upon doped with the high-valence Mo and the clear formation of Co/Fe (oxyhydr)oxides on the surface layers of the exsolved catalyst. This study presents a strategy for the surface reconstruction by combining the exsolution and the high-valence ion doping to develop highly active electrochemical catalysts. [ABSTRACT FROM AUTHOR]

Based on that high-valence cubic perovskite can keep crystalline while Ruddlesden-Popper perovskites tend to become amorphous after oxygen evolution reaction (OER), a unique electrochemistry-include crystalline-amorphous phase on La 0.33 SrCo 0.5 Fe 0.5 O x nanofiber is develpoed as a superior catalyst for OER. La 0.33 SrCo 0.5 Fe 0.5 O x nanofiber triggers an exceptional lattice-oxygen activation mechanism to exhibit a top-level OER performance. [Display omitted] • Nano-sized crystalline-amorphous combination triggers lattice-oxygen activation mechanism to boost oxygen-evolving performance. • La 0.33 SrCo 0.5 Fe 0.5 O x - nanofiber delivers ultra-low overpotential of 260 mV and 240 mV to achieve 10 mA cm−2 in 0.1 M KOH and 1 M KOH, respectively. • Unique crystalline-amorphous combination can be artificially modulated by initial doping level and sintering temperature. The development of crystalline-amorphous phase for oxygen-evolving reaction (OER) in water splitting is lagging, and the underlying catalysis mechanism is still unknown. Here, we can facilely construct electrochemistry-induced crystalline-amorphous phase in hybrid La 0.33 SrCo 0.5 Fe 0.5 O x (H-LSCF) nanofibers based on the behavior of high-valence cubic perovskites and Ruddlesden-Popper perovskites after the OER, where such unique combination can be artificially modulated. This nano-sized combination surpasses its pure-phase counterparts and exhibits ultra-low overpotentials of 260 mV and 240 mV at 10 mA cm−2 in 0.1 M and 1 M KOH, respectively, which can be ascribed to their favorable solid-liquid contact, higher Co valence and stronger Co-O covalency to accelerate OER electron transport. The beneficial changes in various surface properties of H-LSCF ensure its stability for 80 h and 60 h in 0.1 M and 1 M KOH, respectively. In -situ 18O isotope-labelled experiments directly reveal that such combination can trigger exceptional lattice-oxygen activation mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synergistic effects of Co3+ pyr and Co4+ oct were studied for PMS activation. • A model oxide system LnBaCo 2 O 6- δ with tunable Co3+ pyr and Co4+ oct were prepared. • Ordered distribution of active sites in catalyst exerted maximal synergistic effects. • XAS spectrum and DFT calculation were performed to demonstrate the reaction mechanism. • Co3+ pyr contributes to PMS adsorption and Co4+ oct facilitates charge exchange. Synergistic effects are often used in catalyst design for many environmental/energy applications, however, the mechanism and a molecular-level structure to exert maximal synergy effects in catalyzing advanced oxidation processes (AOPs) in wastewater remediation are still unknown. Here, by designing a model perovskite family R BaCo 2 O 6- δ (R = lanthanides) with Co4+ in octahedral coordination (Co4+ oct) and Co3+ in pyramidal coordination (Co3+ pyr), we ambitiously confirm the unique synergy of unsaturated (Co3+ pyr) and metallic (Co4+ oct) Co sites for efficient peroxymonosulfate (PMS) activation. Combined X-ray adsorption spectra and theoretical calculations strongly demonstrate that Co3+ pyr and Co4+ oct synergistically contribute to PMS adsorption and O O bond cleavage, and facilitate Co3+/Co4+ redox cycle for radical generation. With appropriate ratio and ordered distribution of Co3+ pyr/Co4+ oct, the Gd 0.5 La 0.5 BaCo 2 O 5.75 exhibits remarkable catalytic activity for pollutant degradation, outperforming all previously reported Co4+-related oxides. This work may inspire rational design of efficient metal oxide catalysts. [ABSTRACT FROM AUTHOR]

S-modified FeOOH electrocatalysts were prepared via a facile hydrothermal method at 120 °C. The electrocatalyst exhibited an outstanding OER performance with an overpotential of 254 mV at 50 mA·cm−2. The effect of S on the catalytic process was attributed to the formation of (Fe-S)-O*, which reduces the adsorption energy of OH* and increase that of O*, resulting in a smaller ΔG of the rate-determining step. [Display omitted] • S-modified FeOOH was facilely prepared with outstanding OER activity. • Fe4+ improves OER performance. • The (Fe-S)-O* bond was first reported. Surface modification of electrocatalysts is a convenient strategy for addressing the drawbacks arising from the sluggish kinetics of the oxygen evolution reaction (OER). However, the preparation of electrocatalysts usually involves complex procedures, rendering investigation of the catalytic mechanism difficult. In this study, S-modified FeOOH electrocatalysts were prepared via a facile hydrothermal method at 120 °C. The electrocatalyst exhibited an outstanding OER performance with an overpotential of 254 mV at 50 mA·cm−2. Morphological, structural, and electrochemical characterizations revealed that Fe ion is the most important active center. The effect of S on the catalytic process was investigated based on the steric hindrance for OH* adsorption, changes in ΔG of the rate-determining step, and coordination mode of the active species. This is the first report on the formation of an (Fe-S)-O* bond that plays a key role in enhancing the electrochemical performance. [ABSTRACT FROM AUTHOR]

In this work, we report on the discovery of the high-pressure phase of Ba 2 FeS 3 with quasi one-dimensional (1D) spin chains, which was synthesized under high-pressure and high-temperature conditions. A systematic study was carried out via structural, transport, magnetic and thermodynamic measurements. The high-pressure phase of Ba 2 FeS 3 (denoted by Ba 2 FeS 3 (HP)) crystallizes in a K 2 AgI 3 -typed orthorhombic structure with the space group of Pnma (62) and the lattice parameters of a = 8.6831 (1) Å, b = 4.2973 (1) Å, and c = 17.0254 (2) Å, respectively, which consists of chains of corner-sharing FeS 4 tetrahedra along the b axis. Ba 2 FeS 3 (HP) undergoes a long-range antiferromagnetic transition at T N ∼56 K, above which the magnetic susceptibility curve exhibits a round hump behavior with the maximum temperature T max ∼110 K. In addition, the intrachain coupling J intra is about −18 K obtained by using the Wagner-Friedberg model. The specific heat data suggest that the total magnetic entropy change ΔS caused by the long-range ordering transition is only ∼20% of the expected value for a S = 2 system. For comparison, the properties of K 2 CuCl 3 -typed Ba 2 FeS 3 with similar quasi 1D spin chains were presented as well. Our results indicate that both compounds exhibit a typical feature expected for compounds with 1D spin chains. • The new phase of Ba 2 FeS 3 was synthesized under high pressure conditions. • The structure and physical properties of two polymorphs of Ba 2 FeS 3 were studied in detail. • High-pressure phase of Ba 2 FeS 3 displays an antiferromagnetic ground state with one-dimensional spin chains. [ABSTRACT FROM AUTHOR]

Li-Ti Cation Mixing Enhanced Structural and Performance Stability of Li-Rich Layered Oxide The affiliation information for the National Synchrotron Radiation Research Center was presented incorrectly. The authors apologize for any inconvenience caused. [Extracted from the article]

Next generation high energy density lithium‐ion batteries have aroused great interests worldwide. Herein, in a high‐voltage (5 V‐class) LiNi0.5Mn1.5O4/MCMB (graphitic mesocarbon microbeads) battery system using 1 m lithium difluoro(oxalate)borate/sulfolane, tris(trimethylsilyl) phosphite (TMSP) additive is added to significantly improve room/high temperature cycling performances. The unchanged X‐ray diffraction patterns suggest the bulk crystal structure of cycled MCMB anode and LiNi0.5Mn1.5O4 cathode are well preserved. Moreover, soft X‐ray absorption spectroscopy (XAS) taken from bulk sensitive fluorescence‐yield (FY) mode reveals the unchanged bulk electronic structure of cycled LiNi0.5Mn1.5O4 cathode. Therefore, it is concluded that only interface instability contributes to capacity fading of full‐cells. However, electrode/electrolyte interface and corresponding interfacial reaction processes are always "enigmatic." First, X‐ray photoelectron spectroscopy (XPS) and in situ differential electrochemical mass spectrometry (DEMS) are used to more accurately decipher the TMSP additive action mechanism in MCMB/electrolyte interfacial reaction processes, by identifying the interfacial solid and gas byproducts, respectively. Then, the crucial role of TMSP additive in modifying cathode/electrolyte interface is revealed by XPS and soft XAS taken from surface sensitive total electron yield (TEY) mode. This paper provides valuable perspectives for formulating novel electrolytes, and for more accurately depicting additive action mechanism in "enigmatic" electrode/electrolyte interfacial reaction processes. [ABSTRACT FROM AUTHOR]

An AA' 3 B 4 O 12 -type perovskite oxide CaMn 3 (Fe 3 Mn)O 12 was synthesized at 8 GPa and 1473 K. X-ray diffraction shows a cubic crystal structure with space group Im -3. The charge states are verified by soft x-ray absorption spectroscopy to be CaMn3+ 3 (Fe3+ 3 Mn4+)O 12 , where the Ca2+ and Mn3+ are 1:3 ordered respectively at A and A′ sites, while the Mn4+ and Fe3+ are disorderly distributed at B site. The spin interaction of A′-site Mn3+ ions causes a long-range antiferromagnetic phase transition at about 39 K. Subsequently, a spin glass transition is found to occur around 14 K due to the randomly distributed Fe3+ and Mn4+ at B site. Moreover, the spin glass behavior follows a dynamic scaling power law. The temperature dependent resistivity can be well fitted by a 3D Mott variable-range hopping model, indicating the insulating nature of CaMn 3 (Fe 3 Mn)O 12 due to the strong electron correlation effects. A new AA' 3 B 4 O 12 -type oxide CaMn 3 (Fe 3 Mn)O 12 was synthesized at high pressure and high temperature. It crystallizes into an A-site ordered quadruple perovskite structure with space group Im -3. A long-range antiferromagnetic ordering and sequentially a spin glass transition are found to occur with decreasing temperature in this compound. The electrical resistivity measurements show a 3D Mott variable-range hopping behavior. Image 1 • A new compound of CaMn 3 (Fe 3 Mn)O 12 was prepared at high pressure and temperature. • It has an A-site ordered quadruple perovskite structure with space group Im -3. • A long-range antiferromagnetic transition is observed at 39 K due to the spin ordering of A′-site Mn3+ ions. • A spin glass transition is found to occur around 14 K due to the randomly distributed Fe3+ and Mn4+ at B site. • It shows a 3D Mott variable-range hopping behavior. [ABSTRACT FROM AUTHOR]

Li‐rich layered metal oxides are one type of the most promising cathode materials in lithium‐ion batteries but suffer from severe voltage decay during cycling because of the continuous transition metal (TM) migration into the Li layers. A Li‐rich layered metal oxide Li1.2Ti0.26Ni0.18Co0.18Mn0.18O2 (LTR) is hereby designed, in which some of the Ti4+ cations are intrinsically present in the Li layers. The native Li–Ti cation mixing structure enhances the tolerance for structural distortion and inhibits the migration of the TM ions in the TMO2 slabs during (de)lithiation. Consequently, LTR exhibits a remarkable cycling stability of 97% capacity retention after 182 cycles, and the average discharge potential drops only 90 mV in 100 cycles. In‐depth studies by electron energy loss spectroscopy and aberration‐corrected scanning transmission electron microscopy demonstrate the Li–Ti mixing structure. The charge compensation mechanism is uncovered with X‐ray absorption spectroscopy and explained with the density function theory calculations. These results show the superiority of introducing transition metal ions into the Li layers in reinforcing the structural stability of the Li‐rich layered metal oxides. These findings shed light on a possible path to the development of Li‐rich materials with better potential retention and a longer lifespan. [ABSTRACT FROM AUTHOR]