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Fe, Cr, and W are important elements in the alloys of in-reactor materials and operate in high-temperature environments with thermal expansion. Their tritium-impeding abilities are crucial to the radiation safety of various nuclear reactors. In this study, first-principles density functional theory is combined with quasi-harmonic approximation to evaluate factors that can affect the interstitial formation energy and diffusion coefficient of hydrogen isotopes in body-centered cubic (BCC) Fe, Cr, and W, including thermal expansion, metal host lattice vibrations, phonon density-of-states (pDOS) coupling diffusing atoms, and isotope effects. Calculation results indicate that the interstitial formation energy decreases as lattice expansion increases, whereas the jump barriers remain almost constant. Thermal expansion, host lattice vibration, and pDOS coupling minimally affect the diffusion coefficients of hydrogen isotopes in Fe, Cr, and W. The diffusion coefficient ratios between hydrogen isotopes are higher than the inverse ratio of the square root of the isotope mass at low temperatures. However, they decrease to the inverse ratio of the square root of the isotope mass at temperatures exceeding 800 K. This study comprehensively investigates factors that affect the diffusion coefficients of hydrogen isotopes in BCC Fe, Cr, and W, thus providing a firm theoretical foundation for predicting the diffusion coefficients of tritium at different temperatures using protium/deuterium diffusion coefficients. [ABSTRACT FROM AUTHOR]

An Achille's heel of lower-rung density-functional approximations is that the highest-occupied-molecular-orbital energy levels of anions, known to be stable or metastable in nature, are often found to be positive in the worst case or above the lowest-unoccupied-molecular-orbital levels on neighboring complexes that are not expected to accept charge. A trianionic example, [ Cr ( C 2 O 4 ) 3 ] 3 − , is of interest for constraining models linking Cr isotope ratios in rock samples to oxygen levels in Earth's atmosphere over geological timescales. Here we describe how crowd sourcing can be used to carry out self-consistent Fermi–Löwdin–Orbital-Self-Interaction corrected calculations (FLOSIC) on this trianion in solution. The calculations give a physically correct description of the electronic structure of the trianion and water. In contrast, uncorrected local density approximation (LDA) calculations result in approximately half of the anion charge being transferred to the water bath due to the effects of self-interaction error. Use of group-theory and the intrinsic sparsity of the theory enables calculations roughly 125 times faster than our initial implementation in the large N limit reached here. By integrating charge density densities and Coulomb potentials over regions of space and analyzing core-level shifts of the Cr and O atoms as a function of position and functional, we unambiguously show that FLOSIC, relative to LDA, reverses incorrect solute-solvent charge transfer in the trianion-water complex. In comparison to other functionals investigated herein, including Hartree–Fock and the local density approximation, the FLOSIC Cr 1s eigenvalues provide the best agreement with experimental core ionization energies. [ABSTRACT FROM AUTHOR]

Precise measurements of Cr isotopic composition of terrestrial impactites have successfully provided evidence for the presence of extraterrestrial material and have, in some cases, allowed the identification of the type of impactor responsible for the formation of the impact structure. The high Cr abundance in most meteorite groups aids in detecting extraterrestrial contamination while their distinct isotopic compositions can help with the identification of the nature of the projectile. However, this common approach of detection and identification of extraterrestrial contamination using mass‐independent 53Cr and 54Cr variations fails when the impactor type is an iron meteorite because of their low Cr abundances (which are in a similar range to terrestrial rocks). The present study demonstrates the viability of a spallogenic Cr contribution in iron meteorites (resulting from their long cosmic ray exposure times), which compensates for their low Cr abundances and facilitates the identification of iron‐meteoritic contamination in terrestrial impactites. Thus, it broadens the scope of impactors (and impactites) that can be investigated using mass‐independent Cr isotopes from solely chondrites and primitive achondrites to include iron meteorites. The Wabar impact craters are an optimal candidate for this study, characterized by low weathering, diverse impactites, partial meteorite survival, substantial impactor material contamination, and a felsic target lithology with low background Cr concentration. The Cr isotopic composition of the Wabar background sand, which represents the target lithology, is indistinguishable from the terrestrial Cr isotopic composition range, whereas the Wabar iron meteorites show coupled spallogenic excesses in ε53Cr and ε54Cr. The Cr isotopic compositions of Wabar impactites show resolved deviations from the terrestrial Cr isotopic composition, thereby indicating the presence of Wabar meteoritic contamination. Moreover, the study demonstrates that even an impactor with a non‐carbonaceous chondritic origin, such as a IIIAB iron meteorite, can have a carbonaceous chondrite‐like signature in ε54Cr anomalies due to spallogenic Cr contamination. The study advocates for a comprehensive investigation combining platinum group elements and Cr (and/or Ni, Ru) isotopes to accurately characterize impactor types. [ABSTRACT FROM AUTHOR]

A series of garnet-type solid-solution materials, namely NaxCa3−2xGdxIn2Ge3O12:Cr3+ (0 ≤ x ≤ 1.5), were created by introducing cationic disorder into the dodecahedral site, and were found to exhibit a nearly unchanged excitation peak in the blue light region, a wide-range spectral tunability (800–905 nm) and an ultra-broadband spectral coverage (fwhmmax = 205 nm). [ABSTRACT FROM AUTHOR]

Background: In radiotherapy, it is essential to deliver prescribed doses to tumors while minimizing damage to surrounding healthy tissue. Accurate measurements of absorbed dose are required for this purpose. Gafchromic® external beam therapy (EBT) radiochromic films have been widely used in radiotherapy. While the dosimetric characteristics of the EBT3 model film have been extensively studied for photon and charged particle beams (protons, electrons, and carbon ions), little research has been done on α$\alpha$‐particle dosimetry. α$\alpha$‐emitting radionuclides have gained popularity in cancer treatment due to their high linear energy transfer, short range in tissue, and ability to spare surrounding organs at risk, thereby delivering a more localized dose distribution to the tumor. Therefore, a dose‐calibration film protocol for α$\alpha$‐particles is required. Purpose: This study aimed to develop a dose‐calibration protocol for the α$\alpha$‐particle emitting radionuclide 241Am, using Monte Carlo (MC) simulations and measurements with unlaminated EBT3 films. Methods: In this study, a MC‐based user code was developed using the Geant4 simulation toolkit to model and simulate an 241Am source and an unlaminated EBT3 film. Two simulations were performed: one with voxelized geometries of the EBT3 active volume composition and the other using water. The dose rate was calculated within a region of interest in the voxelized geometries. Unlaminated EBT3 film pieces were irradiated with the 241Am source at various exposure times inside a black box. Film irradiations were compared to a 6‐MV photon beam from a Varian TrueBeam machine. The simulated dose rate was used to convert the exposure times into absorbed doses to water, describing a radiochromic‐film‐based reference dosimetry protocol for α$\alpha$‐particles. The irradiated films were scanned and through an in‐house Python script, the normalized pixel values from the green‐color channel of scanned film images were analyzed. Results: The 241Am energy spectra obtained from the simulations were in good agreement with IAEA and NIST databases, having differences <$<$0.516% for the emitted γ$\gamma$‐rays and produced characteristic x‐rays and <$<$0.006% for the α$\alpha$‐particles. Due to the short range of α$\alpha$‐particles, there was no energy deposition in the voxels outside the active 241Am source region projected onto the film surface. Thus, the total dose rate within the voxels covering the source was 0.847 ±$\pm$ 0.003 Gy/min within the sensitive layer of the film (LiPCDA) and 0.847 ±$\pm$ 0.004 Gy/min in water, indicating that the active volume can be considered water equivalent for the 241Am beam quality. A novel approach was employed in α$\alpha$‐film dosimetry using an exponential fit for the green channel, which showed promising results by reducing the uncertainty in dose estimation within 5%. Although the statistical analysis did not reveal significant differences between the 6‐MV photon beam and the α$\alpha$ calibration curves, the dose–response curves exhibited the expected behavior. Conclusions: The developed MC user code simulated the experimental setup for α$\alpha$‐dosimetry using radiochromic film with acceptable uncertainty. Unlaminated EBT3 film is suitable for the dosimetry of α$\alpha$‐radiation at low doses and can be used in conjunction with other unlaminated GafChromic® films for quality assurance and research purposes. [ABSTRACT FROM AUTHOR]

The controllable Curie temperature and high magnetic permeability of NiCuZn ferrites make them promising candidates for magnetic thermal medium. However, the temperature control of existing NiCuZn ferrite materials is not accurate enough to achieve the low Curie temperature required for tumor hyperthermia. In order to further achieve the desired Curie temperature and facilitate the advancement of temperature control materials for tumor hyperthermia, Cr–Mg co-doped NiCuZn ferrite was studied. The study investigated the influence of varying concentrations of Cr3+ on the crystal structure and magnetic properties of Mg–NiCuZn ferrites. The results of structural characterization demonstrate that Cr–Mg co-doped NiCuZn ferrites exhibit high density and uniform distribution of elements. The introduction of Cr3+ leads to a reduction in lattice parameters and a preference for octahedral B-sites. The hysteresis loop results show that the saturation magnetization first increases and then decreases with the increase of Cr3+ concentration. Ni 0.09 Mg 0.20 Cu 0.14 Zn 0.60 Fe 1.89 Cr 0.050 O 3.94 ferrite at 0.30 wt% of Bi 2 O 3 exhibits optimal magnetic characteristics, including a saturation magnetization of ∼36.7 emu/g, low coercivity of ∼0.07 kA/m, high permeability of ∼982.43 @1 MHz, and an appropriate Curie temperature of 45.59 °C. Such permeability and Curie temperature can be used in the body cavity perfusion hyperthermia and deep thermal therapy. [ABSTRACT FROM AUTHOR]

Karoonda-like (CK) carbonaceous chondrites are highly oxidized meteorites, with metal-to-magnetite ratio close to zero. Unlike other carbonaceous chondrites (petrologic type: 1–3), most CK chondrites have undergone thermal metamorphism (550–1270 K) on their parent body with a petrologic type 4 or above. Lines of evidence suggest a genetic relationship between CK chondrites and Vigarano-like (CV) carbonaceous chondrites, which are predominantly type 3. However, observable petrographic distinctions persist between the two groups. Thus, a thorough reevaluation of their geochemical discrepancies is critical to test the CK-CV single parent body hypothesis. Northwest Africa (NWA) 13943, a newly discovered meteorite subjected to intense modification, was classified using scanning electron microscopy and electron microprobe techniques. High-precision measurements of the mass-independent chromium isotope compositions (ε 53 Cr and ε 54 Cr) and the mass-dependent oxygen isotope compositions (δ 17 O and δ 18 O) of NWA 13943 were reported for the first time. Integrating petrological, mineralogical, oxygen, and chromium isotopic data, it is legitimated to infer that CK and CV chondrites may originate from two proximal but distinct isotopic reservoirs within the protoplanetary disk. [ABSTRACT FROM AUTHOR]

By comparing data from an extensive set of Sr and Cr isotope measurements performed on two different thermal ionization mass spectrometers (TIMS), using three sets of Faraday cups with different usage histories, we assess the effects of Faraday cup deterioration on high-precision isotope measurements by TIMS. We find that dynamic 84Sr/86Sr and 87Sr/86Sr measurements provide stable and reproducible results over the entire 56 months of this study, regardless of which set of Faraday cups is used. By contrast, static 84Sr/86Sr and 87Sr/86Sr measurements lead to deviant results, drifts over time, and in general exhibit larger scatter. For the most part, these differences can be attributed to changing Faraday cup efficiencies. For the instruments of this study we find that the center cup is most affected, consistent with this cup often receiving the highest ion beam intensities during measurements conducted in our laboratory. For Cr isotopes, we find that the correlation between mass fractionation-corrected 53Cr/52Cr and 54Cr/52Cr ratios observed for static measurements in several prior studies also reflects different Faraday cup efficiencies. Again, the changing efficiency of predominantly the center cup can account for the observed drift and correlation in 53Cr/52Cr and 54Cr/52Cr. Multi-static Cr isotope measurements reduce this drift, but still result in a residual correlation between the two ratios, suggesting this correlation in part also reflects unaccounted mass fractionation effects. [ABSTRACT FROM AUTHOR]

This research article explores the effect of chromium doping on the non-linear optical properties of strontium tungstate nanostructures. The study analyzes the samples using various techniques such as X-ray diffraction, FTIR, Raman spectroscopy, and photoluminescence studies. The results show that chromium-doped samples exhibit high non-linear absorption coefficient values, and the concentration of chromium affects the absorption behavior. The article also discusses the crystal structure, morphology, and optical properties of the doped nanostructures. The findings suggest that chromium-doped strontium tungstate nanostructures have potential applications in optical limiting and optical switching. [Extracted from the article]

Based on first-principles calculations, this paper presents a study on the stability, electronic structure, ferromagnetic, ferroelectric, and optical properties of Cr2SOCl2 monolayer. The calculations reveal that the Cr2SOCl2 monolayer is a typical magnetoelectric and bipolar magnetic semiconductor with a direct bandgap of 1.25 eV, where the ferromagnetic and ferroelectric ordering can coexist simultaneously below 76 K. The electronegativity difference between S and O atoms leads to a redistribution of charge, which drives the ferroelectric polarization of the Cr2SOCl2 monolayer. The application of uniaxial strain allows for the control of bandgap, light absorption, and carrier mobility in Cr2SOCl2 monolayer. Specifically, when a tensile strain is applied along the y direction, the monolayer undergoes a transition from the bipolar magnetic semiconductor to ferromagnetic half-semiconductor phase. At 12% strain, the absorptivity of Cr2SOCl2 monolayer can reach the maximum (∼8%) within the visible light range; moreover, the mobility of both electrons and holes is large in the x direction, but their difference is small, almost on the same order of magnitude. Based on these findings, we propose that Cr2SOCl2 monolayer under this strain could be a promising ferroelectric photovoltaic material for the absorption layer in solar cells. [ABSTRACT FROM AUTHOR]

There has been much progress on mononuclear chromium(III) complexes featuring luminescence and photoredox activity, but dinuclear chromium(III) complexes have remained underexplored in these contexts until now. We identified a tridentate chelate ligand able to accommodate both meridional and facial coordination of chromium(III), to either access a mono‐ or a dinuclear chromium(III) complex depending on reaction conditions. This chelate ligand causes tetragonally distorted primary coordination spheres around chromium(III) in both complexes, entailing comparatively short excited‐state lifetimes in the range of 400 to 800 ns in solution at room temperature and making photoluminescence essentially oxygen insensitive. The two chromium(III) ions in the dimer experience ferromagnetic exchange interactions that result in a high spin (S=3) ground state with a coupling constant of +9.3 cm−1. Photoinduced energy transfer from the luminescent ferromagnetically coupled dimer to an anthracene derivative results in sensitized triplet‐triplet annihilation upconversion. Based on these proof‐of‐principle studies, dinuclear chromium(III) complexes seem attractive for the development of fundamentally new types of photophysics and photochemistry enabled by magnetic exchange interactions. [ABSTRACT FROM AUTHOR]

The work considers the modelling of nearby supernova (SN) effects on Earth's biosphere via cosmic rays (CRs) accelerated by shockwaves. The rise of the radiation background on Earth resulted from the external irradiation by CR high-energy particles and internal radiation in organisms by the decay of cosmogenic 14C is evaluated. We have taken into account that the CR flux near Earth goes up steeply when the shockwave crosses the Solar System, while in previous works the CR transport was considered as purely diffusive. Our simulations demonstrate a high rise of the external ionization of the environments at Earth's surface by atmospheric cascade particles that penetrate the first 70–100 m of water depth. Also, the cosmogenic 14C decay is able to irradiate the entire biosphere and deep ocean organisms. We analyzed the probable increase in mutation rate and estimated the distance between Earth and an SN, where the lethal effects of irradiation are possible. Our simulations demonstrate that for SN energy of around 1051 erg the lethal distance could be ∼18 pc. [ABSTRACT FROM AUTHOR]

This research addresses an analytical methodology to quantify elements of interest in fusion‐relevant materials using secondary ion mass spectrometry (SIMS). For this purpose, internal standards have been fabricated by ion implantation to avoid the well‐known matrix effect of this technique. In particular, chromium has been implanted at an energy of 12 MeV using two fluences in high‐purity iron and tungsten matrices together with Si control substrates. The latter were applied to determine the Cr concentration implanted through experimental and semiempirical methods. Specifically, the IBA technique Rutherford backscattering spectrometry (RBS) provided the quantitative results being 3.1 × 1019 at/cm3 and 1.6 × 1019 at/cm3 for the high and low dose, respectively. The SIMS depth profiles of Cr for the Fe and W matrices established an ion implantation depth close to 2 μm on both substrates in agreement with the calculations previously performed by Stopping and Range of Ions in Matter (SRIM) simulations. Correlation between the integration of SIMS profiles and known concentrations of the implanted ion resulted in the calibration curve for each matrix, obtaining the SIMS quantification approach by means of this relative sensitivity factor (RSF). Additionally, a cross‐check of the method by comparing commercial Fe‐Cr alloys with the Cr‐implanted Fe matrices of the present study pointed out the need to produce standards with higher chromium concentrations. [ABSTRACT FROM AUTHOR]

NIR luminescent materials have garnered widespread attention because of their exceptional properties, with high tissue penetration, low absorption and high signal-to-noise ratio in the field of optical imaging. However, producing nanophosphors with high quantum yields of emitting infrared light with wavelengths above 1000 nm remains a significant challenge. Here, we prepared a nanoscale ZnGa2O4:xCr3+,yNi2+ phosphor with good luminescence performance in near-infrared emission, which was synthesized via a hydrothermal method and subsequent calcination process. By co-doping with Cr3+ and Ni2+, the ZnGa2O4 phosphor shows a strong broadband emission of 1100-1600 nm in the second near-infrared (NIR-II) region, owing to the energy transfer from Cr3+ to Ni2+ with an efficiency up to 90%. Meanwhile, a near-infrared phosphor-conversion LED (NIR pc-LED) device is fabricated based on the ZnGa2O4:0.8% Cr3+,0.4%Ni2+ nanophosphor, which has under 100 mA input current, an output power of 23.99 mW, and a photoelectric conversion efficiency of 7.53%, and can be effectively applied in imaging and nondestructive testing. Additionally, the intensity ratio of INi/ICr of ZnGa2O4:0.8% Cr3+,0.4%Ni2+ with its high sensitivity value of 4.21% K-1 at 453 K under 410 nm excitation, indicates its potential for thermometry application. [ABSTRACT FROM AUTHOR]

Understanding the stable strontium isotope fractionation between seawater and ferromanganese crusts/nodules is crucial for reconstructing seawater Sr isotopic history. This study explores stable Sr isotope fractionation during adsorption to manganese oxides, as preliminary experiments indicated their higher Sr adsorption capacity compared to iron oxides. We observed that equilibrium in concentration and isotopic composition can be achieved within a day. The lighter isotope (86Sr) is preferentially adsorbed, with the fractionation extent showing no significant change with respect to reaction time, pH, or Sr concentration under low ionic strength conditions (−0.14‰). Equilibrium fractionation processes, rather than Rayleigh fractionation, more accurately represent the isotopic composition trends of dissolved and adsorbed Sr. Experiments in synthetic seawater demonstrated greater Sr isotope fractionation (−0.20‰) compared to low ionic‐strength solutions. This fractionation during adsorption by manganese oxides in synthetic seawater is consistent with the isotopic discrepancy between seawater and ferromanganese nodules, suggesting that Mn oxide adsorption is the primary mechanism for Sr accumulation in ferromanganese deposits. These results imply that ferromanganese deposit Sr isotopic compositions could be proxies for reconstructing seawater Sr isotopic history, which is influenced by carbonate burial and continental weathering, reflecting the global carbon cycle changes. Plain Language Summary: Strontium isotope records in seawater can inform us about the history of continental weathering and marine carbonate burial. To reconstruct these records from marine sediments, we need consistent Sr isotope fractionation between seawater and the sediments. Our experiments focused on manganese oxide minerals in ferromanganese deposits, which are potential carriers for this purpose. Findings indicate that stable Sr isotopes undergo equilibrium fractionation during adsorption by manganese oxides, and this process in synthetic seawater matches the Sr isotopic offset found between seawater and natural ferromanganese nodules. Consequently, the stable Sr isotopic composition of ferromanganese deposits may consistently differ from that of seawater. This suggests the potential of ferromanganese deposits to reconstruct the historical stable Sr isotopic composition of seawater. Key Points: Lighter strontium isotopes are preferentially adsorbed by manganese oxidesFractionation magnitude is consistent across varying reaction times, pH levels, and strontium concentrationsThe stable strontium isotopic offsets between seawater and ferromanganese nodules align with those observed in adsorption experiments [ABSTRACT FROM AUTHOR]

The rapid growth of industrialization has led to the uncontrolled pollution of the environment, and rapid action is needed. This study synthesized Ag/TiO2/polyvinyl alcohol (PVA) nano photocatalyst for promising light-derived photocatalytic removal of heavy metal ions. The design of experiment (DOE) was used to study the effect of important factors (pH, reaction time, and photocatalyst dosage) to maximize the final performance of the photocatalyst. In the optimized condition, the Ag/TiO2/PVA nano-photocatalyst removed more than 94% of Cr6+ in 180 min, and the efficiency was more than 70% for Cu2+, Zn2+, and Ni2+ metal ions. The adsorption of the heavy metal ions on the photocatalyst was described well with the Langmuir isotherm, while the pseudo-second-order linear kinetic model fitted with the experimental data. The nano-photocatalyst's stability was confirmed after maintaining its performance for five successive runs. The enhanced photocatalytic activity for the heavy metal ions removal can be attributed to the presence of metallic silver nanoparticles (electron transfer and plasmonic fields mechanisms) and PVA, which delayed the recombination of electron–hole. The synthesized ternary Ag/TiO2/PVA nano-photocatalyst showed promising performance for the elimination of heavy metal ions and can be used for environmental remediation purposes. [ABSTRACT FROM AUTHOR]

The stable chromium isotope system has been widely used as a redox proxy to reconstruct the oxygenation history of ocean atmosphere systems. However, the Cr isotope mass balance in modern oceans (i.e., inputs and outputs) remains poorly constrained. To investigate the influence of seawater‐peridotite reaction on the global marine Cr isotope mass balance, we report high‐precision Cr isotope data (δ53Cr) on a series of fresh and altered abyssal peridotites from the Gakkel Ridge and the Southwest Indian Ridge (SWIR). The least altered peridotites give a δ53Cr value of −0.08 ± 0.06‰ (2SD, n = 4) for the oceanic mantle which is consistent with the established δ53Cr of the Bulk Silicate Earth. Compared to fresh peridotites, a subset of altered peridotites exhibit a loss of isotopically light Cr with relatively positive δ53Cr values (up to 0.04‰). These altered peridotites are characterized by significant Cr loss and likely have been subject to serpentinization. By contrast, seafloor weathering has limited influence on the Cr concentrations and isotopic compositions of the altered peridotites. Monte Carlo (MC) simulations of marine alteration suggest a net Cr flux into seawater from altered abyssal peridotites of ∼3.5 × 108 mol/yr, which is on the same order of magnitude as the riverine input flux of 108–109 mol/yr. Furthermore, the MC results suggest that the peridotite‐sourced net Cr flux has a negative δ53Cr signature (−0.33 ± 0.21‰, 2SD). Thus, seawater‐peridotite interactions must be considered when evaluating the modern oceanic Cr isotope mass balance. Plain Language Summary: The stable chromium isotope system is an emerging paleoredox proxy for tracing Earth's atmospheric oxygenation over geological timescales. However, accurately inferring past Earth's atmospheric oxygenation levels using chromium isotopes requires a more precise understanding of the elemental and isotopic cycling of chromium, particularly within the oceans. By studying abyssal peridotites which are rocks found beneath the oceanic crust, we find that specific types of alterations in these rocks, particularly the process of serpentinization, have an impact on the chromium isotopes. These findings provide insights into the mechanisms involved in transporting chromium from the deep Earth mantle to the oceans. We discover that these altered rocks release a flux of isotopically light chromium into the ocean, which is comparable to the amount coming from rivers. Our study sheds new light on the complex interactions between seawater and abyssal peridotites, which potentially exert a profound impact on the global marine Cr isotope mass balance. Key Points: The first data set of stable Cr isotopic compositions for abyssal peridotitesSeafloor weathering has insignificant impact on the Cr isotopic compositions of abyssal peridotitesSeafloor alteration exerts a key control on the Cr isotopic composition of seawater [ABSTRACT FROM AUTHOR]

The capacity to manipulate magnetization in 2D dilute magnetic semiconductors (2D‐DMSs) using light, specifically in magnetically doped transition metal dichalcogenide (TMD) monolayers (M‐doped TX2, where M = V, Fe, and Cr; T = W, Mo; X = S, Se, and Te), may lead to innovative applications in spintronics, spin‐caloritronics, valleytronics, and quantum computation. This Perspective paper explores the mediation of magnetization by light under ambient conditions in 2D‐TMD DMSs and heterostructures. By combining magneto‐LC resonance (MLCR) experiments with density functional theory (DFT) calculations, we show that the magnetization can be enhanced using light in V‐doped TMD monolayers (e.g., V‐WS2, V‐WSe2). This phenomenon is attributed to excess holes in the conduction and valence bands, and carriers trapped in magnetic doping states, mediating the magnetization of the semiconducting layer. In 2D‐TMD heterostructures (VSe2/WS2, VSe2/MoS2), the significance of proximity, charge‐transfer, and confinement effects in amplifying light‐mediated magnetism is demonstrated. We attributed this to photon absorption at the TMD layer that generates electron–hole pairs mediating the magnetization of the heterostructure. These findings will encourage further research in the field of 2D magnetism and establish a novel design of 2D‐TMDs and heterostructures with optically tunable magnetic functionalities, paving the way for next‐generation magneto‐optic nanodevices. [ABSTRACT FROM AUTHOR]

Soft magnetic materials with high magnetic susceptibility in response to the influence of alternating magnetic fields, generate an inductive electric voltage in the receiving coil, the spectrum of which contains higher harmonics. This is due to the nonlinear dependence of magnetization on the magnetic field, and the amplitudes of higher harmonics make a significant contribution to the overall signal if an external field leads to magnetic saturation. Magnetic susceptibility and saturation field are largely determined by magnetoelastic interactions in amorphous ferromagnets, respectively, the amplitudes of higher harmonics should depend on external mechanical stresses. In this work, we study the processes of magnetization reversal in amorphous microwires of two compositions: Co71Fe5B11Si10Cr3 and Co66.6Fe4.28B11.51Si14.48Ni1.44Mo1.69 under the action of external tensile stresses. For the first composition, mechanical stresses exceeding a certain limit (higher than 350 MPa) lead to the transformation of the magnetic hysteresis from a bistable type to an inclined one. In this case, a sharp change of the harmonic spectrum is observed. In microwires of the second composition with an initially inclined loop, external stresses cause a monotonous increase in the slope of the hysteresis loop (a decrease in susceptibility). In this case, the amplitudes of higher harmonics change significantly at low stresses, lower than 100 MPa. The results were obtained by magnetization reversal of microwire samples using a system of flat coils, which demonstrates the potential of using these materials as wireless sensors of mechanical stresses with remote reading. [ABSTRACT FROM AUTHOR]

A series of chromium-doped calcium ferrite samples of composition Ca0.5Mg0.5Fe12−xCrxO19 (x = 0.0, 0.5, 1.0, 1.5, 2.0) was meticulously prepared using the standard sol-gel combustion route. Structural and morphological properties were comprehensively studied via X-ray diffraction and Scanning Electron Microscopy (SEM). The lattice parameters 'a' and 'c' unequivocally validated the space group of the samples as P63/mmc (194). Moreover, the lattice parameters derived from the XRD data demonstrated commendable agreement with the values extrapolated from theoretical cation distribution and Rietveld refinement calculations. It was further confirmed that the crystallite size, as determined by XRD, concurred excellently with the particle size measurements from the scanning electron micrographs. The samples' magnetic characterization was carried out using a vibrating sample magnetometer (VSM). Notably, the saturation magnetization (Ms) and remanence (Mr) were found to exhibit an increase, while coercivity (Hc) displayed a concurrent decrease with higher substitution ratios. The reason behind the enhancement of saturation magnetization and remanence, along with the reduction in coercivity, was elucidated based on involved factors such as crystallite size, anisotropy constant, and cation distribution. Results showed that including chromium significantly softened the ferrite materials, making them ideal for advanced high-end recording applications. The samples also exhibited low coercivity and impressive saturation magnetization, enhancing their value as storage devices tailored for information storage and recording purposes. [ABSTRACT FROM AUTHOR]

The nucleosynthetic Cr isotope anomalies provides useful information to trace the source and origin of extraterrestrial samples, but it is usually influenced by high‐energy cosmic rays, and evaluating such effect of cosmic rays in lunar samples is especially important. Those cosmic radiation particles (primary particles) can react with lunar materials, creating many secondary particles. Both primary and secondary particles can produce cosmogenic nuclides on the Moon. Radiation Environment and Dose at the Moon (REDMoon) is a novel GEANT4 Monte‐Carlo model built to simulate the interactions of space particles with the lunar surface and subsurface content. Using this model, we simulate the production of cosmogenic Cr isotopes (50Cr, 52Cr, 53Cr, 54Cr) at different depths of lunar surface, and compare the contribution of different reactions generating these nuclides. The results suggest that spallation reactions are the most important process producing cosmogenic Cr isotopes. We also analyze the relationship between 53Cr/52Cr and 54Cr/52Cr predicted by our model and compare it with different Apollo samples. As previously studied, we also find an approximate linear relationship between ɛ53Cr and ɛ54Cr, where ɛ53Cr (or ɛ54Cr) is the relative deviation from the standard 53Cr/52Cr ratio (or 54Cr/52Cr ratio), normalized to 1/10,000. Furthermore, we reveal a change of this linear relationship in different depths of lunar surface. Besides, we investigate how the slopes can be influenced by exposure age and the Fe/Cr ratio. With these additional factors carefully considered, the comparison between our modeled results and the measurements is better than previous studies. Plain Language Summary: Cosmic rays arriving at the Moon can change the isotopic compositions on the lunar surface including chromium isotopes which can be used to constrain the evolution history of the Moon. Here, we use the particle transport model to simulate the high‐energy particles and the chromium isotopes generated in the lunar material by different cosmic ray sources. We compare different processes producing cosmogenic Cr isotopes and suggest that the spallation reactions play the main role. After taking the effect of solar energetic particles and the decay of cosmogenic 53Mn into consideration, we reach a better agreement between our model prediction and the Apollo lunar samples about the relationship between ɛ53Cr and ɛ54Cr. Such an improved analysis of the lunar cosmogenic nuclides contributes to a better understanding of the origin of the Moon. Key Points: We simulate the production rate of cosmogenic 50Cr, 52Cr, 53Cr, 54Cr in lunar terrain with Radiation Environment and Dose at the Moon modelWe compare the contributions of different processes producing Cr isotopesWe analyze the relationship between 54Cr/52Cr and 53Cr/52Cr constraining lunar evolution models [ABSTRACT FROM AUTHOR]

In the tetraazamacrocyclic ligand N,N'‐dimethyl‐2,11‐diaza‐[3.3](2,6)pyridinophane (L‐N4Me2), the two pyridine units are separated from each other by sp3‐hybridized triatomic bridges. Such electronically isolated pyridine moieties are considerably less prone to reductions than di‐ or triimines. A detailed structural, magnetic, and spectroscopic investigation of the complexes [Cr(L‐N4Me2)(OAc)2] and [Cr(L‐N4Me2)(OAc)2](PF6), in combination with theoretical calculations, reveals that the reduced complex must be described as a chromium(III) ion coordinated to the anionic radical ligand (L‐N4Me2)⋅− rather than a low‐spin chromium(II) ion bound to closed‐shell ligands. Thus, it is, to the best of our knowledge, only the second example of a stable and structurally characterized metal complex containing a reduced isolated pyridine unit. The stability is attributed to the delocalization of the unpaired electron across the two pyridine units, mediated by their interaction to the metal ion. [ABSTRACT FROM AUTHOR]

Chromium complexes containing a bis(diphenylphosphino) ligand have attracted significant interest over many years due to their potential as active catalysts for ethylene oligomerisation when combined with suitable co-catalysts such as triethylaluminium (TEA) or methylaluminoxane (MAO). While there has been considerable attention devoted to the possible reaction intermediates and the nature of the Cr oxidation states involved, the potential UV photoactivity of the Cr(I) complexes has so far been overlooked. Therefore, to explore the photoinduced transformations of bis(diphenylphosphino) stabilized Cr(I) complexes, we used continuous-wave (CW) EPR to study the effects of UV radiation on a cationic [Cr(CO)4(dppp)]+[Al(OC(CF3)3)4]− complex (1), where dppp represents the 1,3 bis-(diphenylphosphino)propane ligand, Ph2P(C3H6)PPh2. Our preliminary investigations into the photochemistry of this complex revealed that [Cr(CO)4(dppp)]+ (1) can be readily photo-converted into an intermediate mer-[Cr(CO)3(κ1-dppp)(κ2-dppp)]+ complex (2) and eventually into a trans-[Cr(CO)2(dppp)2]+ complex (3) in solution at room temperature under UV-A light. Here, we show that the intermediate species (2) involved in this transformation can be identified by EPR at much lower temperature (140 K) and at a specific wavelength (highlighting the wavelength dependency of the reaction). In addition, small amounts of a 'piano-stool'-type complex, namely [Cr(CO)2(dppp-η6-arene)]+ (4), can also be formed during the photoconversion of [Cr(CO)4(dppp)]+ using UV-A light. There was no evidence for the formation of the [Cr(L-bis-η6-arene)]+ complex (5) in these UV irradiation experiments. For the first time, we also evidence the formation of a 1-hexene coordinated [Cr(CO)3(dppp)(1-hexene)]+ complex (6) following UV irradiation of [Cr(CO)4(dppp)]+ in the presence of 1-hexene; this result demonstrates the unprecedented opportunity for exploiting light activation during Cr-driven olefin oligomerisation catalysis, instead of expensive, difficult-to-handle, and hazardous chemical activators. [ABSTRACT FROM AUTHOR]

Zinc chromium oxide (Cr/ZnO, 5wt.%) was prepared by a facile chemical co-precipitation route. The structure, composition, and chemical bonding were analyzed using X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FTIR) indicating that chromium ions were integrated the host framework to form Cr/ZnO nanocomposite. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) micrographs showed comb-shaped nanoparticles with an average size 20 nm and large surface area. The energy gap of the thin films was estimated from T% and R% measurements which exhibit a strong optical absorption edge close to the visible spectrum. The insecticidal activity of the synthesized nanocombs against C. pipiens larvae was evaluated with LC50 (30.15 ppm) and LC90 (100.22 ppm). Besides, the nanocomposite showed high antibacterial performance against gram-positive bacteria (Bacillus subtilis) and gram-negative bacteria (Proteus vulgaris) with inhibition zones 21.9 and 19 mm, respectively. [ABSTRACT FROM AUTHOR]

This article reports the effect of 3d-transition metal ions on the optical features of chromium ions bearing glass host. Interestingly, this study unveiled the charge transfer of Cr ions at high energy (at 347 nm), which is often hidden in earlier reports due to its vicinity to the glass edge, and its immersion in the lattice band of the glass host. In addition to the well-defined charge transfer at low energy (at 378 nm). In this vein, glass composition [ (TM) 1 − (B 2 O 3) 80 − (BaO) 18.7 − (Cr 2 O 3) 0.3 ] , where TM is the transition metal ions in their oxide form, was prepared via the melt-quenching method at about 1100 °C. X-ray diffraction patterns confirmed the amorphous structure of the glass, and the chemical composition was examined using energy-dispersive X-ray spectra. The decrease in density (from 2.74 gcm − 3 to 2.59 gcm − 3 ) and the increase in molar volume (from 31.92 cm 3 mol − 1 to 34.32 cm 3 mol − 1 ) were demonstrated. Moreover, the refractive index is attained at an average value (1.50). The glass structure was studied using infrared spectroscopy, which elucidated an increase in N 4 (33.2%–37.5 %) and an increase in NBO (15.3%-18.4 %). Bewitshingly, the charge transfer of Cr 6 + ions, at high energy (347 nm), was explored. This, in turn, leads to a proper investigation of glass absorption edges that undergo a blue shift of about 1.25 eV. Adding 3d-transition metal ions affects crystal field splitting energy and interelectronic interaction within the d-orbitals of Cr ions. Finally, ESR data confirmed the Cr 5 + state (with ESR signal at 1.92) and Cr 3 + state (with ESR signal at 4.6, 4.07 and 2.04) of chromium ions. Such a cohesive investigation of the structure, optical and magnetic properties of 3d-transition metal ions-bearing chromium barium borate glass paved the route toward utilization of these samples in the optoelectronic realm. [ABSTRACT FROM AUTHOR]

Permian intermediate–felsic igneous rocks, widely distributed in the southern Beishan orogen, provide crucial constraints on the geodynamic process of the late Paleozoic Paleo-Asian Ocean. New zircon U–Pb dating using LA–ICP–MS determines the age of the northern Qingshan diorites, the Heishantou quartz diorites, and the southern Qingshan biotite granodiorites at 300 Ma, 294 Ma, and 291–286 Ma, respectively. Their whole-rock compositions exhibit arc-like geochemical features. Moreover, their zircon trace elements show the characteristics of continental arc zircons. The diorites, characterized by low SiO2, high MgO with Mg# (50–52), and low Cr, Co, and Ni, display enrichment in Sr-Nd-Hf isotopes (87Sr/86Sr = 0.7060 to 0.7061; ℇNd(t) = −1.4 to −1.7; ℇHf(t) = −4.7 to −0.6), originating from the fractionation process of magma derived from the enriched mantle. The quartz diorites show moderate SiO2 and variable MgO (2.75–3.84 wt%) and exhibit enrichment in Sr-Nd (87Sr/86Sr = 0.7048–0.7050; ℇNd(t) = −1.5–+0.9) and depletion in zircon Hf isotopes (ℇHf(t) = 3.8 to 7.8). Combined with their high Y (20.0–21.0 ppm) and low (La/Yb)N (6.0 to 17.2), we conclude that they originated from the juvenile lower crust previously influenced by oceanic sediments, with the input of enriched mantle-derived materials. The biotite granodiorites display low A/CNK (0.91–0.97), 10000*Ga/Al (1.8–1.9), and Ti-in-zircon temperatures (average 711 °C), indicating that they are I-type granitoids. These rocks show enrichment in Sr-Nd isotopes (87Sr/86Sr = 0.7054 to 0.7061; ℇNd(t) = −2.0 to −1.6) and many variable zircon Hf isotopes (ℇHf(t) = −2.3 to +4.5). Geochemical studies indicate that they originate from the mixing of magmas derived from the enriched mantle and preexisting juvenile lower crust. All these data imply the existence of oceanic subduction in southern Beishan during the early Permian. Integrating these results with previous studies, it is inferred that the retreating subduction of the Liuyuan Ocean contributed to early Permian intermediate–felsic rocks becoming widespread in the Shibanshan unit, the southernmost part of the Beishan orogen, and also why the Paleo-Asian Ocean in southern Beishan did not close during the early Permian. [ABSTRACT FROM AUTHOR]

Gamma radiation indicators are appropriate tools for monitoring visually whether or not the irradiation process has been carried out properly. Among chemical radiation indicators available worldwide, a few are suitable for monitoring low dose ranges (especially for blood irradiation, below 50 Gy). Addressing this scope, PVA Fricke gel was proposed in this work. Irradiation of the prepared PVA Fricke gel samples was performed by Co-60 gamma cell unit up to a dose of 80 Gy. Color change of the samples was observed from orange to purple proportional to increasing absorbed dose. Prepared samples were divided into three groups, kept at different environmental conditions, to investigate stability of the gel against temperature and light. Results revealed that the irradiated samples kept at dark and refrigerator were stable for seven days. Optical absorbance measurement of the samples also estimated pre- and post-irradiation color stability. The gel can be easily used to identify processed and unprocessed products in blood irradiation. Although the gel is designed to be a qualitative indicator, it is also a good quantitative dosimeter for gamma rays. [ABSTRACT FROM AUTHOR]

Transition metal chromium (Cr) ion‐doped inorganic materials exhibit distinct tunable broadband near‐infrared luminescence, and they have promising applications including nondestructive composition analysis, night vision, biomedicine, plant illumination, and afterglow anticounterfeiting. Currently, the most critical issue is to optimize their full width at half maxima, thermal stability, and internal/external quantum efficiency. This review systematically summarizes strategies to effectively improve the photoluminescence performance of near‐infrared‐emitting materials with transition metal chromium ions. Key examples of the design and preparation of Cr ion‐doped luminescence with different transition modes, a detailed discussion of strategies to effectively improve the photoluminescence properties of near‐infrared luminescent materials, and a summary of generic strategies to help explore novel and efficient Cr‐doped phosphor materials are provided. Next, the latest developments and trends in these Cr ion‐doped phosphor materials are presented for a variety of application scenarios. Finally, future research directions and new challenges faced are also discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Positively fractionated Cr isotopes in Late Neoproterozoic Urucum iron formation. • Link to oxygenated atmosphere and surface hydrosphere during Marinoan glaciation. • Deposition of IF in restricted, periodically ice-covered and stratified sub-basins. Cr isotopes recorded in iron formations (IF) are considered to have the potential to reflect the isotope signatures in respective ambient surface seawater. The ∼600 Ma Fe and Mn deposits pertaining to the Banda Alta Formation (Urucum district, Mato Grosso do Sul, Brazil), comprise the world's youngest and largest Neoproterozoic sedimentary Fe and Mn formations (MnF). Shale normalized Rare Earth Element and Yttrium (REY) patterns of drillcore samples show flat, positively sloped patterns with absent Europium anomalies and near- to supra-chondritic Yttrium-Holmium ratios with negative Cerium anomalies, which imply intermittent mixing of freshwater with seawater. Redox sensitive element enrichment factors (Mo EF , U EF , Cr EF) show positive correlation, indicating varying redox conditions across the Jacadigo Basin, with ephemeral euxinic conditions. The Cr isotope signatures across the Urucum IF (δ 53Cr auth at: Morraria Grande + 0.93 ± 0.34 ‰, 2 σ , n = 28; Morro do Rabichão + 0.5 ± 0.4 ‰, 2 σ , n = 3; and Morro do Urucum ca. + 0.64 ‰, n = 1) are statistically indistinguishable from previously published surface outcrop samples at Morro do Urucum. Our new data support: (1) a stable supply of oxidized Cr potentially from continental sources at the time of deposition, implying high atmospheric O 2 levels in the Late Neoproterozoic; (2) insignificant alteration of the authigenic Cr isotope signals by tropical weathering despite surface iron up-concentration and leaching of carbonates, and (3) lack of isotope effects that would be associated with non-quantitative reduction processes and accompanying particulate transport to the chemical sediments in the Jacadigo Basin. The combined information from (isotope)geochemical data presented herein speak for a deposition of the Urucum IFs in restricted, periodically ice-covered and stratified sub-basins with partial connection to the open ocean, and for the presence of a sufficiently oxidative atmosphere which promoted a continuous supply of the surface waters with isotopically heavy Cr from the weathering landmasses at this time. [ABSTRACT FROM AUTHOR]

Nitrogen and chromium co-doped cadmium sulfide nanocomposites (NCps) were successfully synthesized using a simple co-precipitation method (Cpm). To evaluate their structural attributes, X-ray diffraction (XRD) analysis, conducted with X'pert high score plus software, confirmed the composite nature and established their particle size within the nano range, measuring between 1 to 1.6 nm. Further characterization, employing Fourier transform infrared spectroscopy (FTIR) confirms the presence of Cr and N. The energy dispersive X-ray spectroscopy (EDX) provided compelling evidence of the integration of chromium and nitrogen into the CdS host matrix. An interesting outcome of the UV-VIS diffused reflectance spectra (DRS) analysis was the significant blue shift observed in the band gap resulting from the introduction of chromium, accompanied by a Burstein-Moss effect, leading to a red shift as the nitrogen concentration increased. The intense green light emission witnessed in photoluminescence (PL) studies was associated with the trapping of nitrogen and Cr2+ within F-centers. Moreover, vibrating sample magnetometer (VSM) investigations unveiled distinct magnetic behaviors of the nanocomposites, particularly at low magnetic fields. These findings reveal a potential for tailoring band gaps and presenting novel magnetic properties, which could hold substantial promise for applications in optomagnetic and spintronic smart devices. [ABSTRACT FROM AUTHOR]

Dissipation of heat efficiently from a hot object via radiation while minimizing the inward heat conduction is the key requirement of radiation thermal protection. In this study, a Ca‐Cr co‐doped Y3NbO7 coating with lamellar porous structure is fabricated, which shows an ultra‐low thermal conductivity (<0.7 W m−1 K−1) and near‐unity emissivity (>0.9) across a broad wavelength range of ≈1–24 µm. This record high emissivity to thermal conductivity ratio (≈1.3) is experimentally and theoretically revealed from a multi‐scale perspective. The diffusoin‐mediated thermal conduction feature of niobates combined with lamellar porous structure of the coating reduces its thermal conductivity to an impressive 0.5 W m−1 K−1 at 25 °C, surpassing the theoretical amorphous limitation of 0.72 W m−1 K−1. Experiments and FDTD calculation results demonstrate that the intrinsic emissivity dips at shallow extinction wavelengths (1 and 8 µm) and strong phonon‐polariton resonances wavelengths (>13 µm) can be effectively compensated by the multiple scattering/absorption and gradual modulation of conical shape/effective refractive index induced by surface micro‐protrusion structures, respectively. Furthermore, the coating exhibits robust mechanical and thermal stability with a high bonding strength (18.3 MPa) and thermal expansion coefficient (≈11 × 10−6 K−1 at 1200 °C) comparable to YSZ, showing great potential in the radiation thermal protection field. [ABSTRACT FROM AUTHOR]

The presence of Cr ions in wastewater must be treated before being released into the environment due to its detrimental impact on both the environment and human health. In this study, the removal of Cr (VI) ions from an aqueous solution was investigated by adsorption using an adsorbent derived from agriculture wastes, banana pseudo stem. The adsorbent was prepared by oven-drying the banana stem waste at 105°C for 24 h. The surface structure of the adsorbent was characterized using scanning electron microscopy (SEM). Batch adsorption experiments were carried out to determine the removal efficiency of Cr (VI) ions based on four adsorption operation parameters: pH of the solution, adsorbent dosage, contact time and initial concentration of ion solution. At room temperature, the highest Cr (VI) ions removal of 88.2% was achieved using 0.5 g banana pseudo stem adsorbent, with an initial concentration of chromium solution of 500 ppm at pH 2 and after 90 min of contact time. For the equilibrium study, the experimental data were better fitted by the Langmuir isotherm model with a maximum adsorption capacity of 33.33 mg/g. Meanwhile, the kinetic isotherm was best fitted by the pseudo-second-order model. Therefore, the banana pseudo stem showed great potential as an efficient, low-cost and natural green adsorbent for Cr (VI) ions removal from an aqueous solution via adsorption. [ABSTRACT FROM AUTHOR]

Previous work on Cr isotope composition of the lithospheric mantle focused on shallow spinel-facies peridotites and invoked the effects of partial melting and metasomatism. However, little is known on the Cr isotope composition and behavior in the deeper and more voluminous garnet-facies mantle, notably during generation and passage of magmas and fluids. Here, we present Cr isotope data for 26 garnet and ten spinel whole-rock peridotite xenoliths (mainly harzburgites) from the Udachnaya kimberlite on the Siberian craton and minerals from five of them, as well as for minerals of 14 eclogites and four garnet clinopyroxenites from the Dabie orogen in eastern China. Garnet (Gt) and clinopyroxene (Cpx) are major Cr hosts in the mantle. Our ionic modeling suggests the following order of 53Cr/52Cr values in coexisting minerals: garnet ≈ spinel > Cpx > olivine. Cr isotopes are equally partitioned between garnet and Cpx in four peridotites, while garnet is enriched in heavy Cr in one peridotite and all the eclogites (Δ53Cr Gt-Cpx 0.01‰ to 0.27‰, av. 0.10‰), but depleted in heavy Cr in the pyroxenites (Δ53Cr Gt-Cpx −0.03‰ to −0.16‰, av. −0.10‰). The Δ53Cr Gt-Cpx variations are attributed to effects of chemical composition, equilibration temperature and oxygen fugacity on equilibrium Cr isotope fractionation. Further, the anomalous Δ53Cr Gt-Cpx values in the Dabie pyroxenites and one peridotite may indicate disequilibrium inter-mineral isotope fractionation via kinetic diffusion during phase transitions as a result of pressure-temperature (P-T) changes and metasomatism. The whole-rock δ53Cr range in the garnet peridotites (−0.27 to 0.13‰; average −0.08 ± 0.18‰, 2 SD, n = 25, excluding an outlier with −0.86‰) overlaps bulk silicate Earth estimates whereas the spinel peridotites tend to have higher δ53Cr (−0.12 to 0.16‰; av. 0.02 ± 0.20‰, 2 SD, n = 10). While these rocks are residues of high degrees (30–40%) of melt extraction, their range contrasts with limited equilibrium Cr isotope fractionation we calculated for melting residues of both spinel and garnet peridotites (Δ53Cr residue-source < 0.03‰). The δ53Cr values in the spinel peridotites show correlations with modal abundances of Cpx, garnet and spinel, as well as major and trace element composition. We posit that the Cr isotope variations in these peridotites are somehow linked to solid–melt and inter-mineral diffusive exchanges during P-T changes, deformation and ingress of metasomatic media previously documented in the Udachnaya peridotites. The average δ53Cr value (−0.09 ± 0.16‰, 2 SD, n = 31) for garnet peridotites (excluding U9) in this and previous studies is similar to those previously obtained for (mainly off-craton) spinel peridotites and komatiites, and appears to be representative of the Cr isotope composition for bulk mantle. Numerical modeling for mantle magmas derived at different depths and by different melting degrees of garnet and spinel peridotites and eclogites yields a narrow δ53Cr range, possibly affected by oxygen fugacity. [ABSTRACT FROM AUTHOR]

NH2-UiO-66@TCNQ composites (NUxTCy) were fabricated from NH2-UiO-66 and organic superconductor 7,7,8,8-tetracyanoquinodimethane (TCNQ) by a green ball-milling method. The as-prepared optimum NU90TC10 demonstrated 100% photocatalytic Cr(VI) reduction at an initial concentration of 5 mg L−1 within 50 min under low-power ultraviolet (UV) light. All experiments confirmed that the introduction of low dosage TCNQ into NH2-UiO-66 could promote Cr(VI) elimination. The results of electron spin resonance (ESR) tests, photochemical Pt0 deposition and electrochemical experiments confirmed that the TCNQ superconductor could improve the photocatalytic Cr(VI) removal by accelerating the separation of charge carriers over NH2-UiO-66. The factors influencing the photocatalytic Cr(VI) elimination over NU90TC10, like pH, hole scavengers and foreign ions, were investigated. The NU90TC10 composite demonstrated excellent stability and practicability up to five cycles. This work provided a new photocatalyst candidate for boosted photocatalytic Cr(VI) elimination under low power LED light. [ABSTRACT FROM AUTHOR]

Using the method of dynamic light scattering, it was found that the rate of collagen cleavage under the influence of bacterial collagenase decreases by almost 4 times when protein molecules are doped with Cr3+ ions, and when the enzyme activator of Zn2+ ions is added, it increases by 1.3 times. Based on the experimental data, the reaction rate constants k1 were calculated. It was found that when collagen molecules are tanned with a chromium salt, it becomes more resistant to degradation in solutions containing zinc ions than in solutions with the addition of calcium ions, as we described in earlier works. [ABSTRACT FROM AUTHOR]

Fluids released through the dehydration of serpentinite can be rich in Cl−, which enables the significant mobility of Cr in subduction zones. However, the Cr isotope behavior accompanying the mobility of Cr during serpentinite dehydration is still poorly constrained. Here, we report high‐precision Cr isotope data for a unique suite of serpentinites that represent metamorphic products at different depths in oceanic subduction zones. Low‐grade serpentinites affected by significant Cr loss during serpentinization exhibit remarkably higher δ53Cr, while samples with Cr contents >∼1,800 ppm typically preserve mantle‐like δ53Cr. Antigorite serpentinites have an average δ53Cr value of −0.17‰ ± 0.19‰ (n = 12, 2SD), which is statistically lower than those of low‐grade serpentinite (−0.05‰ ± 0.30‰, n = 80, 2SD) and higher‐grade chlorite harzburgite (−0.10‰ ± 0.27‰, n = 22, 2SD). This suggests that resolvable Cr isotope fractionation occurs during serpentinite dehydration, which is explained by the variability of Cr isotope behavior in the presence of Cl‐bearing fluids at different dehydration stages. No obvious Cr isotope fractionation was found during chlorite harzburgite dehydration, probably related to the limited Cr mobility in a Cl‐poor fluid. Other processes, such as melt extraction, external fluid influx and retrograde metamorphism, have negligible effects on the Cr isotope systematics of meta‐serpentinites. Fluids released by serpentinite dehydration may have a great effect on the Cr isotope heterogeneity of mantle wedge peridotites and arc magmas. Plain Language Summary: Serpentinite plays an important role in crust–mantle interaction and arc magmatism in oceanic subduction zones. Serpentinite‐derived fluids potentially mobilize Cr in the form of Cl complexes. However, there is limited information available about the Cr isotope compositions of subducted serpentinites, hindering the understanding of Cr isotope behavior during the dehydration of serpentinite. Here, we first report high‐precision Cr isotope data for a unique suite of (meta‐)serpentinite that encompasses low‐pressure oceanic serpentinite to metamorphic products of complete dehydration at great depth. Our results fill the gap in the Cr isotope composition of meta‐serpentinites metamorphosed under diverse P–T conditions in oceanic subduction zones. We found that there is variable and significant Cr isotope fractionation during prograde dehydration of serpentinites. Such serpentinite‐derived fluids may contribute to the Cr isotope heterogeneity of mantle wedge peridotites and arc magmas. Key Points: First high‐precision Cr isotope compositions on a unique suite of meta‐serpentinitesOceanic serpentinites with significant Cr loss tend to exhibit remarkably higher δ53CrSignificant Cr isotope fractionation occurs during prograde dehydration of serpentinites in subduction zones [ABSTRACT FROM AUTHOR]

The purpose of this study is to conduct theoretical investigations on the electronic, structural and magnetic properties of lithium niobate (LiNbO3) doped with different concentrations of the transition metal chromium (Cr). All properties of LiNb1−xCrxO3 compounds (x = 0.25, 0.50 and 0.75) are achieved with spin-polarized density functional theory by the GGA-PBE and the TB-mBJ approximations. To ensure the stability of the LiNb1−xCrxO3 quaternary alloy in the ferromagnetic state, the total energy released from the optimized structure and the defect formation energy were calculated. The classical Heisenberg model estimated the Curie temperature of the compounds. The material studied exhibits a 100% spin-polarized semi-metallic ferromagnetism behaviour. In all compounds, the data of the magnetic moment demonstrated that the chromium impurity atom is the most important source by comparison with the Nb and Li, which have minor contributions. In addition, the magnetic moment of the Cr atoms decreases with doping; this comes from the p–d hybridization between the Cr-3d and O-2p states. The half-metal gap (GHM), the most important factor in spintronics applications, was also calculated. In addition, to assess the effects of the exchange separation process, the crystal field separation energy, the exchange separation parameters, and the exchange constants N0α, N0β, and ΔEC, ΔEV are predicted. [ABSTRACT FROM AUTHOR]

The analytical expression of the density-dependent binding energy per nucleon for the relativistic mean field (RMF), the so-called relativistic energy density functional (Relativistic-EDF), is used to obtain the isospin-dependent symmetry energy and its components for the isotopic chain of Sc-, Ti-, V- and Cr-nuclei. The procedure of the coherent density fluctuation model is employed to formulate the Relativistic-EDF and Brüeckner energy density functional (Brüeckner-EDF) at local density. A few signatures of shell and/or sub-shell closure are observed in the symmetry energy and its components, i.e. surface and volume symmetry energy, far from the β -stable region for odd- A Sc- and V-, and even–even Ti- and Cr- nuclei with nonlinear NL3 and G3 parameter sets. A comparison is made with the results obtained from Relativistic-EDF and Brüeckner-EDF with both NL3 and G3 for the considered isotopic chains. We find Relativistic-EDF outperforms the Brüeckner-EDF in predicting the shell and/or sub-shell closure of neutron-rich isotopes at N = 5 0 for these atomic nuclei. Moreover, a relative comparison has been made for the results obtained with the nonlinear NL3 and G3 parameter sets. [ABSTRACT FROM AUTHOR]

Chromium is an important redox-active element, with significant Cr isotope fractionations driven by redox transformations in the natural environment and quantified through laboratory experiments. Recent work has demonstrated that non-redox-driven transformations can also produce small variations in Cr isotopes, but the role of these processes in controlling environmental Cr isotope variations remains unclear. The highly acidic but biologically diverse acid rock drainage system in Río Tinto, Spain (and affiliated rivers) provides a unique opportunity to examine how non-redox-related processes can substantially affect the isotopic composition of Cr in a natural system. Our results suggest that under conditions where Cr redox transformations are obviated, Cr cycling is largely controlled by formation of Fe-oxyhydroxides and Fe-hydroxysulfates, Cr adsorption, and Cr speciation, with little apparent Cr isotope fractionation between source materials, waters, and sediments. Moderate Cr isotope shifts, however, may be the result of non-redox processes, including adsorption to organic ligands and potentially biological uptake. These results add to a growing body of evidence for the importance of non-redox transformations in contributing to environmental Cr isotope variations, with implications for the use of chromium isotopes in studies of sedimentary Cr isotope records. In particular, this study is a validation of the potential for sulfide weathering in the Proterozoic to deliver relatively unfractionated Cr isotopes to the ocean, despite rising and sustained high oxygen levels. [ABSTRACT FROM AUTHOR]

The only experimentally proved method of synthesis of superheavy elements (SHE) is the use of fusion reactions with heavy ions. Modeling of complicated dynamics of nuclear reactions induced by heavy ions is done within a multidimensional dynamical model of nucleus-nucleus collisions based on the Langevin equations. The model gives a continuous description of the system evolution starting from the well-separated target and projectile in the entrance channel of the reaction up to the formation of final reaction products. In this paper, we study fusion dynamics in competition with dominating channels of quasifission and deep inelastic transfer. The estimates have been made for cross sections for synthesis of new neutron-enriched isotopes of known SHE in -evaporation channels as well as fusion cross section for reactions with Ti and Cr ions leading to yet unknown SHE with and 120. [ABSTRACT FROM AUTHOR]

Stable isotopes of chromium (Cr) and iron (Fe), both multivalent elements in silicate melts, are valuable proxies of redox conditions in magmatic systems. Partial melting and fractional crystallization have been identified as the dominant fractionation processes for Cr and Fe isotopes in high-temperature reservoirs that can lead to small but detectable isotope variations in igneous rocks. More recently, however, the source mineralogy has been suggested to play an important role, which can ultimately affect the magnitude of Cr and Fe isotopic fractionation during partial melting and thus the Cr and Fe isotopic composition of the originating melt. With the aim to investigate the role of magmatic processes and the source Cr and Fe isotope signatures on the isotope composition of these transition metals in normal mid-ocean ridge basalts (N-MORB), we analyzed 21 well-characterized MORB glasses from the southern East-Pacific Rise, Pacific-Antarctic Ridge and Mid-Atlantic Ridge. The Cr isotope compositions of N-MORB show a narrow range from −0.278 to −0.186 ‰ in δ53/52Cr (i.e., difference of a sample's 53Cr/52Cr ratio relative to the international reference material NIST SRM979), with an average value of −0.237 ± 0.050 ‰ (2SD; n = 19). As such, the average N-MORB δ53/52Cr value is significantly lower than that of Bulk Silicate Earth of −0.12 ± 0.06 ‰ and the Cr isotope compositions reported for most ocean island basalts ranging from ∼ −0.23 to 0.00 ‰. Iron isotopic compositions of these MORB range from +0.032 to +0.137 ‰ in δ56/54Fe (i.e., difference of a sample's 56Fe/54Fe ratio relative to the international reference material IRMM014) and are within the range of previously published MORB data. The lack of correlations between N-MORB Cr isotope signatures and indices of magmatic differentiation suggests a negligible control of this process on Cr stable isotopes. Partial melting modeling using pMELTS provides evidence that the significant offset towards lower δ53/52Cr values of N-MORB cannot be produced by decompression partial melting of a lherzolithic source such as the depleted upper mantle alone. Instead, we suggest that the lower δ53/52Cr values of MORB could be linked to intrinsic small-scale 53Cr-depleted pyroxene-rich domains in the upper mantle that influence the melt's Cr isotopic budget during partial melting. [ABSTRACT FROM AUTHOR]

The co-depositions of Cr-Zr and those of Cr-Zr-O coatings of 500 nm thick were made using magnetron sputtering in continuous mode, in a circular enclosure with a volume of 0.05 m³ evacuated prior to the deposition process under 10-6 mbar vacuum conditions. Silicon and Carbon substrates measuring 12x15mm were used for deposition. The topology of all of the CrZr and CrZrO2 coatings deposited on silicon and carbon substrates have been investigated by Scanning Electron Microscopy (SEM) at three magnifications: 1000x, 5000x and 10.000x. For all of the coatings deposited on Silicon substrates, at all three magnifications, was observed very smooth surfaces with only small topological elements. In some samples, few droplets of around 100nm can be observed. The appearance of particulates is caused by the arching events that occur at target surface during the deposition proces and are more pronounced during reactive sputtering. The coatings deposited on the Carbon substrate show more morphological features as these substrates have a lower grade surface polish finish as to sliced Silicon wafers; the deposited film tends to follow the substrate topology and cracks can be seen on the surface. Were investigated the mechanical properties of the samples of Cr+Zr, respectively Cr+Zr+O2 using The Bruker Hysitron TI 980 TriboIndenter which allows to extrapolate mechanical properties such Young’s Modulus (YM) and Hardness (H). The experimental results obtained through nanoindentation studies, show: In the absence of oxygen during deposition ( Zr-Cr structures), the Young’s Modulus and Hardness are influenced by the concentration ratio of the two components Cr and Zr, i.e., there is the practical possibility of adjusting the two parameters YM and H by correspondingly changing the concentrations of the components of the structure . In the case of the Cr+Zr+O2 structures, for sample where the concentration of Chromium is maximum and the concentration of Zirconium is minimum, the presence of Oxygen causes a decrease for YM and respectively a decrease for H (in this case Cr-O bonds are predominant). In the case of sample in which the concentration of Zirconium is maximum and the concentration of Chromium is minimum, in the presence of Oxygen (now the bonds Zr-O being predominant), an increase for YM and an increase for H are observed. The crystalline structure was investigated using X-Ray Diffraction (XRD) method, using a setup composed of a diffractometer equipped with a Cu-Kα X-ray sourse, with a specific wavelength of 0.154nm, in a Bragg-Bretano type geometry. In the case of the Cr-Zr sample, diffractograms show that only the peaks corresponding to the Si substrate are visible, highlighting the amorphous character of the structure. Also, the measurements reveal the amorfous character of the Cr-Zr-O sample. In order to highlight the effect of the element Cr together with Zr and O, the diffractogram of the ZrO2 sample and diffractogram of Cr-Zr-O sample are examinated for comparison. Considering the application of these materials in dentistry, the 2 wide amorphous strips in the case of ZrO2 sample and amorfous character found in the case of Cr-Zr-O sample, could correspond to the adhesive used to attach the veneer to the tooth of such structures. From this perspective, it can be stated that the presence of the Cr element in the Cr-Zr-O structure widens the possibility of its use as an adhesive to attach the veneer to the tooth. [ABSTRACT FROM AUTHOR]

Cr3+-doped broadband infrared luminescent materials have attracted growing attention in consideration of their potential applications in phosphor-converted infrared light sources. However, discovering infrared-emitting luminescent materials with ultrabroadband emission and excellent thermal stability still remains a challenge. In this work, we report the significant improvement of infrared photoluminescence properties in Na3ScSi3O9:Cr3+ phosphor via Li+ substitution and Yb3+ codoping. The prepared Na3ScSi3O9:Cr3+ phosphor can produce broad infrared emission over 650–1350 nm with a peak maximum at 898 nm under the excitation of blue light. Through the substitution of Li+ for Na+, the maximum infrared emission peak can be tuned from 898 nm to 850 nm. When the Li+ content is 0.5, the integrated infrared luminescence intensity of the obtained Na2.5Li0.5ScSi3O9:Cr3+ phosphor increases by 4.2 times compared with that of the Na3ScSi3O9:Cr3+ phosphor, and the luminescence thermal stability is also improved significantly (58.5%@100 °C). Moreover, Yb3+ codoping can simultaneously realize the characteristic infrared luminescence of Cr3+ and Yb3+, resulting in a broadened spectral width due to efficient energy transfer from Cr3+ to Yb3+. Finally, an ultrabroadband infrared light-emitting diode prototype is fabricated through a combination of the optimized Na2.5Li0.5ScSi3O9:2%Cr3+,0.5%Yb3+ phosphor with a commercial 490 nm LED chip, giving an infrared output power of 5.2 mW at 320 mA drive current. This work provides an effective way to optimize the infrared photoluminescence performance of Cr3+-doped Na3ScSi3O9 infrared phosphors. [ABSTRACT FROM AUTHOR]

Cr3+-activated phosphors with high quantum efficiency show excellent promise in the field of near-infrared (NIR) phosphor converted light-emitting diodes (pc-LEDs). Here, we design an annealing program for Cr3+-doped phosphors containing variable valence elements that cannot be prepared in a reducing atmosphere to enhance their luminescence efficiency and thermal stability. A novel phosphor, Li2Mg3SnO6:Cr3+, developed by this annealing design, containing variable valence element Sn, exhibits higher quantum efficiency and better thermal stability than the one prepared by the conventional solid-state reaction. The Li2Mg3SnO6:0.03Cr3+ sample exhibits broadband NIR emission with a full width at half-maximum (FWHM) of 201 nm. After annealing, the internal quantum efficiency (IQE) and external quantum efficiency (EQE) of the Li2Mg3SnO6:0.03Cr3+ sample are enhanced from 48.5% to 84.7% and from 22.7% to 32.6%, respectively, and the thermal quenching temperature at which the luminescence intensity of the phosphor reduces to half of its initial value is promoted from ∼400 K to ∼425 K. The luminescence intensity of the optimized Li2Mg3SnO6:0.03Cr3+ sample at 425 K (∼152 °C) remains 49.2% of its initial intensity at 300 K. A NIR pc-LED is fabricated by combining the optimized Li2Mg3SnO6:0.03Cr3+ sample with a blue LED (455 nm blue chip), and the NIR radiant fluxes of 3.676 mW (at 10 mA) and 29.21 mW (at 100 mA), as well as a maximum NIR photoelectric efficiency of 14.2%, are obtained. The results show that this novel phosphor has great application potential in NIR pc-LEDs, and the annealing design exhibits huge potential for improving the optical properties of Cr3+-activated phosphors. [ABSTRACT FROM AUTHOR]

The discovery of magnetic order in atomically-thin van der Waals materials has strengthened the alliance between spintronics and two-dimensional materials. An important use of magnetic two-dimensional materials in spintronic devices, which has not yet been demonstrated, would be for coherent spin injection via the spin-pumping effect. Here, we report spin pumping from Cr2Ge2Te6 into Pt or W and detection of the spin current by inverse spin Hall effect. The magnetization dynamics of the hybrid Cr2Ge2Te6/Pt system are measured, and a magnetic damping constant of ~ 4–10 × 10−4 is obtained for thick Cr2Ge2Te6 flakes, a record low for ferromagnetic van der Waals materials. Moreover, a high interface spin transmission efficiency (a spin mixing conductance of 2.4 × 1019/m2) is directly extracted, which is instrumental in delivering spin-related quantities such as spin angular momentum and spin-orbit torque across an interface of the van der Waals system. The low magnetic damping that promotes efficient spin current generation together with high interfacial spin transmission efficiency suggests promising applications for integrating Cr2Ge2Te6 into low-temperature two-dimensional spintronic devices as the source of coherent spin or magnon current. Spin-pumping experimental technique where a DC or AC spin current is generated, and typically transferred to a heavy metal layer where it can be detected via electrical measurements. While well established in conventional materials, coherent spin-pumping in van der Waals magnetic materials is challenging due to the low damping and high-quality interface requirements. Here, Xu et al demonstrate coherent spin pumping in the van der Waals magnet Cr2Ge2Te6. [ABSTRACT FROM AUTHOR]

The results of determination of impurities contained in an artificial neutrino source in the BEST experiment are presented. A Cr source of activity 3.6 MCi was produced by exposing enriched chromium to thermal neutrons in a nuclear reactor. The amount of impurities was estimated by lines in the spectrum of photons from the source. It is shown that the contribution of radioactive isotopes associated with the impurities to the energy deposition in the source is negligible in relation to the energy deposition of Cr. A high purity of the material from which the source was manufactured is demonstrated. The cross section for neutron capture by a number of elements is estimated. [ABSTRACT FROM AUTHOR]

The Cr isotope ratios of terrestrial and extra‐terrestrial materials are emerging as one of the most important tracers in geosciences. Previous studies on Cr isotopic measurements using TIMS have found that there is residual Cr isotopic fractionation between the mass‐fractionation‐corrected 53Cr/52Cr and 54Cr/52Cr ratios, which may cause an offset of obtained ratios from the reference values. The residual fractionation was thought to be caused by the evaporation of Cr‐oxide species during thermal ionisation, but the mechanism by which this residual fractionation could be reduced remained unclear. Here we revisit the issue of residual fractionation and propose that this problem can be alleviated by utilising W filaments instead of conventionally used Re filaments for Cr ionisation. Using W filaments, the formation of CrO+ was suppressed during heating as the filament temperature was ~ 100 °C lower than when Re filaments were used. In repeated measurement of a carbonaceous chondrite, the intermediate precisions of 53Cr/52Cr and 54Cr/52Cr ratios in the W filament runs were two to three times better than those of the Re filament runs. Therefore, the new finding of this study will be of key importance for future studies of Cr isotopes for terrestrial and extra‐terrestrial materials. [ABSTRACT FROM AUTHOR]

The Dhala structure in north‐central India is a confirmed complex impact structure of Paleoproterozoic age. The presence of an extraterrestrial component in impactites from the Dhala structure was recognized by geochemical analyses of highly siderophile elements and Os isotopic compositions; however, the impactor type has remained unidentified. This study uses Cr isotope systematics to identify the type of projectile involved in the formation of the Dhala structure. Unlike the composition of siderophile elements (e.g., Ni, Cr, Co, and platinum group elements) and their inter‐element ratios that may get compromised due to the extreme energy generated during an impact, Cr isotopes retain the distinct composition of the impactor. The distinct ε54Cr value of −0.31 ± 0.09 for a Dhala impact melt breccia sample (D6‐57) indicates inheritance from an impactor originating within the non‐carbonaceous reservoir, that is, the inner Solar System. Based on the Ni/Cr ratio, Os abundance, and Cr isotopic composition of the samples, the impactor is constrained to be of ureilite type. Binary mixing calculations also indicate contamination of the target rock by 0.1–0.3 wt% of material from a ureilite‐like impactor. Together with the previously identified impactors that formed El'gygytgyn, Zhamanshin, and Lonar impact structures, the Cr isotopic compositions of the Dhala impactites argue for a much more diverse source of the objects that collided with the Earth over its geological history than has been supposed previously. [ABSTRACT FROM AUTHOR]