Electronic structure and spin state regulation of vanadium nitride via a sulfur doping strategy toward flexible zinc-air batteries

Owing to the distinctive structural characteristics,vanadium nitride(VN)is highly regarded as a catalyst for oxygen reduction reaction(ORR)in zinc-air batteries(ZABs).However,VN exhibits limited intrinsic ORR activity due to the weak adsorption ability to O-containing species.Here,the S-doped VN anchored on N,S-doped multi-dimensional carbon(S-VN/Co/NS-MC)was constructed using the solvothermal and in-situ doping methods.Incorporating sulfur atoms into VN species alters the electron spin state of vanadium in the S-VN/Co/NS-MC for regulating the adsorption energy of vanadium sites to oxygen molecules.The introduced sulfur atoms polarize the V 3d_(z)^(2) electrons,shifting spin-down electrons closer to the Fermi level in the S-VN/Co/NS-MC.Consequently,the introduction of sulfur atoms into VN species enhances the adsorption energy of vanadium sites for oxygen molecules.The*OOH dissociation transitions from being unspontaneous on the VN surface to a spontaneous state on the S-doped VN surface.Then,the ORR barrier on the S-VN/Co/NS-MC surface is reduced.The S-VN/Co/NS-MC demonstrates a higher half-wave potential and limiting current density compared to the VN/Co/N-MC.The S-VN/Co/NS-MC-based liquid ZABs display a power density of 195.7 m W cm^(-2),a specific capacity of 815.7 m A h g^(-1),and a cycling stability exceeding 250 h.The S-VN/Co/NS-MC-based flexible ZABs are successfully employed to charge both a smart watch and a mobile phone.This approach holds promise for advancing the commercial utilization of VN-based catalysts in ZABs.

Effect of content and spin state of iron on electronic properties and floatability of iron-bearing sphalerite:A DFT+U study

Iron is an impurity widely occurred in sphalerite,and its effect on sphalerite flotation is complex.In this work,the effects of iron content and spin state on electronic properties and floatability of iron-bearing sphalerite are comprehensively studied using density functional theory Hubbard U(DFT+U)calculations combined with coordination chemistry flotation.The band gap of ideal sphalerite is 3.723 eV,and thus electron transition is difficult to occur,resulting in poor floatability.The results suggest the band gap of sphalerite decreases with increasing iron content.For low iron content,the decreased band gap facilitates electron transition;at this case,Fe^(2+)in a high-spin state possesses oneπelectron pair,which can form a weakπ-backbonding with xanthate,causing increasing floatability.However,for medium and high iron-bearing sphalerite,with the further decrease of band gap,Fe^(2+)is oxidized to Fe^(3+)due to electrochemical interaction,and henceπ-backbonding is eliminated,leading to lower floatability of iron-bearing sphalerite,which is consistent with the flotation experimental results.This work could give a deeper understanding of how sphalerite flotation behaviors are affected by iron content.

Phase diffusion of a two-component Bose-Einstein condensates:exact and short-time solutions for arbitrary coherent spin state

We investigate phase diffusion of a two-component Bose--Einstein condensates prepared initially in arbitrary coherent spin state ｜θ0,φ0｜. Analytical expression of the phase-diffusion time is presented for θ0～π/2 case. In comparison with the symmetrical case （i.e., θ0=π/2）, we find that the diffusion process becomes slow due to the reduced atom number variance.

Multipartite entanglement concentration of electron-spin states with CNOT gates

We propose a different entanglement concentration protocol （ECP） for nonlocal N-electron systems in a partially entangled Bell-type pure state using the CNOT gates and the projection measurements on an additional electron. For each nonlocal N-electron system, Alice first entangles it with the additional electron, and then she projects the additional electron onto an orthogonal basis for dividing the N-electron systems into two groups. In the first group, the N parties obtain a subset of N-electron systems in a maximally entangled state directly. In the second group, they obtain some less-entangled N-electron systems, which are the resource for the entanglement concentration in the next round. By iterating the entanglement concentration process several times, the present ECP has the maximal success probability, which is the theoretical limit of an ECP, equal to the entanglement of the partially entangled state, and higher than the others. This ECP may be useful in quantum computers based on electron-spin systems in the future.

Low Mantle Perovskite:Solid Solution, Spin State of Iron and Water Solubility

Silicate perovskites（（Mg, Fe）SiO 3 and CaS iO 3） are believed to be the major constituent minerals in the lower mantle. The phase relation, solid solution, spin state of iron and water solubility related to the lower mantle perovskite are of great effect on the geodynamics of the Earth＇s interior and on ore mineralization. Previous studies indicate that a large amount of iron coupled with aluminum can incorporate into magnesium perovskite, but this is discordant with the disproportionation of（Mg,Fe）SiO 3 perovskite into iron-free MgS i O3 perovskite and hexagonal phase（Mg0.6Fe0.4）SiO 3 in the Earth＇s lower mantle. MnS iO 3 is the first chemical component confirmed to form wide range solid solution with Ca SiO 3 perovskite and complete solid solution with MgS i O3 perovskite at the P-T conditions in the lower mantle, and addition of Mn Si O3 will strongly affects the mutual solubility between Mg Si O3 and CaS iO 3. The spin state of iron is deeply depends on the site occupation of the Fe3＋or Fe2＋, the synthesis and the annealing conditions of the sample. It seems that the spin state of Fe2＋ in the lower mantle perovskite can be settled as high spin, however, the existence of intermediate spin or low spin state of Fe2＋ in perovskite has not been clarified. Moreover, different results have also been reported for the spin state of Fe3＋ in perovskite. The water solubility of the lower mantle perovskite is related with its composition. In pure Mg SiO 3 perovskite, only less than 500 ppm water was reported. Al–Mg Si O3 perovskite or Al–Fe–MgS iO 3 perovskite in the lower mantle accommodates water of 1100 to 1800 ppm. Further experiments are necessary to clarify the detailed conditions for perovskite solid solution, to reliably analyze the valence and spin states of iron in the coexisting iron-bearing phases, and to compare the water solubility of different phases at different layers for deeply understanding the geodynamics of the Earth＇s interior and ore mineralization.

Influence of annealing on spin state of cobalt ions in La_(1-x)Sr_xCoO_3(0≤x≤0.5) system

Perovskite oxide La1-xSrxCoO3（0≤x≤0.5） series were prepared and effect of oxygen annealing on crystal structure and magnetic susceptibility were studied.High-temperature susceptibility could be well fitted by Curie-Weiss law for all Sr-doped samples.Weiss constant and effective magnetic moment were determined, and their variations with Sr doping and oxygen annealing condition were obtained.The result suggested that by assuming that the Co3＋ ions were in the intermediate-spin（IS） state, most of the Co4＋ ions in the as-prepared samples might be in the high-spin（HS） state, but both the Co3＋ and Co4＋ ions might be in the IS state after oxygen annealing, which indicated that annealing in flowing oxygen could cause transition of the spin state of Co4＋ ions from the HS state to IS state.

High-Spin States in ^(141)Pm

The high-spin states of 141pro nucleus have been studied by using in-beam v-ray spectroscopy technology through the126Te（19F, 4n） reaction at a beam energy of 90 MeV. The previous level scheme has been extended with spin up to 49/2 h. Many new levels and transitions are identified. Five collective band structures are observed. Based on systematic comparison with the neighboring nuclei, two bands with strong AI = 1 M1 transitions inside the bands are proposed as the oblate bands with γ--60°, and three bands with large signature splitting have been suggested as the oblate-triaxial deformation with γ--90°. The characteristics for these bands have been discussed.

Low Spin State Dinuclear Fe^Ⅲ,Ni^Ⅱand Cu^ⅡComplexes Supported by 1-Amino-2-indanol Schiff Base Derivatives

Four complexes of compositions [Fe2（L^1）2]（1）, [Ni2（L^1）2]（2）, [Ni2（L^2）2]（3） and [Cu2（L^2）2]（4）（H2L^1 = 1-（（（2-hydroxy-2,3-dihydro-1 H-inden-1-yl）imino）methyl）naphthalen-2-ol, H2L^2 = 4-（（2-hydroxy-2,3-dihydro-1 H-inden-1-yl）imino）pentan-2-one） were synthesized under solvothermal conditions. The structures of 1~4 were characterized by X-ray single-crystal diffraction analysis. The magnetic properties of these four complexes are investigated. The dc magnetic measurements indicate that the metal ions of 1, 2 and 3 are in the low spin state, revealing the strong ligand field character of 1-amino-2-indanol. This work provides an effective approach to coordination complexes possessing low spin state metal centers.

Optimizing the electronic spin state and delocalized electron of NiCo_(2)(OH)_(x)/MXene composite by interface engineering and plasma boosting oxygen evolution reaction

The electrocatalytic activity of transition-metal-based compounds is closely related to the electronic configuration.However,optimizing the surface electron spin state of catalysts remains a challenge.Here,we developed a spin-state and delocalized electron regulation method to optimize oxygen evolution reaction(OER)performance by in-situ growth of NiCo_(2)(OH)_(x) using Oswald ripening and coordinating etching process on MXene and plasma treatment.X-ray absorption spectroscopy,magnetic tests and electron paramagnetic resonance reveal that the coupling of NiCo_(2)(OH)_(x) and MXene can induce remarkable spin-state transition of Co^(3+)and transition metal ions electron delocalization,plasma treatment further optimizes the 3 d orbital structure and delocalized electron density.The unique Jahn-Teller phenomenon can be brought by the intermediate spin state(t2 _(g)^(5) e_(g)^(1))of Co^(3+),which benefits from the partial electron occupied egorbitals.This distinct electron configuration(t2_(g)^(5) e_(g)^(1))with unpaired electrons leads to orbital degeneracy,that the adsorption free energy of intermediate species and conductivity were further optimized.The optimized electrocatalyst exhibits excellent OER activity with an overpotential of 268 m V at 10 m A cm^(-2).DFT calculations show that plasma treatment can effectively regulate the d-band center of TMs to optimize the adsorption and improve the OER activity.This approach could guide the rational design and discovery of electrocatalysts with ideal electron configurations in the future.

Effect of Surface Site on the Spin State for the Interaction of NO with Pd2, Rh2 and PdRh Nanoparticles Supported at Regular and Defective MgO(001) Surfaces

An attempt has been made to analyze the effect of surface site on the spin state for the interaction of NO with Pd2, Rh2 and PdRh nanoparticles that supported at regular and defective MgO(001) surfaces. The adsorption properties of NO on homonuclear, Pd2, Rh2, and heteronuclear transition metal dimers, PdRh, that deposited on MgO(001) surface have been studied by means of hybrid density functional theory calculations and embedded cluster model. The most stable NO chemisorption geometry is in a bridge position on Pd2 and a top configuration of Rh2 and PdRh with N-down oriented. NO prefers binding to Rh site when both Rh and Pd atoms co-exist in the PdRh. The natural bond orbital analysis (NBO) reveals that the electronic structure of the adsorbed metal represents a qualitative change with respect to that of the free metal. The adsorption properties of NO have been analyzed with reference to the NBO, charge transfer, band gaps, pairwise and non-pairwise additivity. The binding of NO precursor is dominated by the E(i)Mx-NO pairwise additive components and the role of the support was not restricted to supporting the metal. The adsorbed dimers on the MgO surface lose most of the metal-metal interaction due to the relatively strong bond with the substrate. Spin polarized calculations were performed and the results concern the systems in their more stable spin states. Spin quenching occurs for Rh atom, Pd2, Rh2 and PdRh complexes at the terrace and defective surfaces. The adsorption energies of the low spin states of spin quenched complexes are always greater than those of the high spin states. The metal-support and dimer-support interactions stabilize the low spin states of the adsorbed metals with respect to the isolated metals and dimers. Although the interaction of Pd, Rh, Pd2, Rh2 and PdRh particles with Fs sites is much stronger than the regular sites O2-, the adsorption of NO is stronger when the particular dimers are supported on an anionic site than on an Fs site of the MgO(001). The encountered variations in magnetic properties of the adsorbed species at MgO(001) surface are correlated with the energy gaps of the frontier orbitals. The results show that the spin state of adsorbed metal atoms on oxide supports and the role of precursor molecules on the magnetic and binding properties of complexes need to be explicitly taken into account.

Quasiprobability Distribution of Squeezed Thermal Spin States in Ferromagnet

<Abstract>We study squeezed properties of magnon squeezed thermal spin states by using the distribution of Q function in the ferromagnet.It is found that the distribution of Q function strongly depends on the temperature T and coupling parameter γ.Below the transition temperature T_c,the distribution Q function in the squeezed thermal spin state presents a richer structure than in the normal state.Non-classical effects have been observed.In the transition from the normal to the squeezed thermal spin state,the phase symmetry of the magnon system is spontaneously broken.

Disentanglement of a Singlet Spin State in a Coincidence Stern-Gerlach Device

We analyze the spin coincidence experiment considered by Bell in the derivation of Bells theorem. We solve the equation of motion for the spin system with a spin Hamiltonian, Hz, where the magnetic field is only in the z-direction. For the specific case of the coincidence experiment where the two magnets have the same orientation the Hamiltonian Hz commutes with the total spin Iz, which thus emerges as a constant of the motion. Bells argument is then that an observation of spin up at one magnet A necessarily implies spin down at the other B. For an isolated spin system A-B with classical translational degrees of freedom and an initial spin singlet state there is no force on the spin particles A and B. The spins are fully entangled but none of the spin particles A or B are deflected by the Stern-Gerlach magnets. This result is not compatible with Bells assumption that spin 1/2 particles are deected in a Stern-Gerlach device. Assuming a more realistic Hamiltonian Hz + Hx including a gradient in x direction the total Iz is not conserved and fully entanglement is not expected in this case. The conclusion is that Bells theorem is not applicable to spin coincidence measurement originally discussed by Bell.

Shell Model Investigation of High Spin States for Ce Isotopes

-A truncated shell model approach is presented for studying the properties oflow-lying states as well as the high-spin states in even-even nuclei with the help of thegeneralized boson-fermion expansion technique.The primary fermion state space isspanned by the interacting valence protons and neutrons with effective nucleon-nucleonforce.The truncated model space is considered as a direct sum of two subspaces corre-sponding to the configurations of（sd）N and（sd）N-1,respectively,plus a broken fermionpair.Numerical calculations are carried out for 130～134Ce isotopes.The calculated spec-trum reproduces the experimental data quite well,especially the backbending appearingin these nuclei.The results suggest that the approach is able to describe the spectroscopyof states with angular momenta up to J≈20.

A Microscopic Investigation of High-Spin States for ^(162)Hf and ^(164)Hf Isotopes

A truncated shell model approach is applied to the description of high-spinstates for 162Hf and 164Hf isotopes.The backbends of the moment of inertia are repro-duced well by the calculation.The results show that the approach is able to investigatethe yrast states of nuclei in rare earth region.

Investigation of the Spin Crossover Complex [Fe(bapbpy)(NCS)_2 ] in Its Low-spin and Highspin State by DFT/TD-DFT/BS-DFT Calculations

The spin crossover（SCO） compound [Fe（bapbpy）（NCS）2],where bapbpy contains two fused N,N-bis（2-pyridyl）amines,has been studied by DFT/TD-DFT/BS-DFT methods.Several density functionals and basis sets were used in the calculation to obtain optimized geometries of the compound in the low-（LS） and high-spin（HS） states.The vibrational modes and IR spectra,spin splitting energies,excited states and UV/Vis absorption spectra were obtained.The structural parameters of the calculated isolated complex are in good agreement with the X-ray data.We investigate three dimers of [Fe（bapbpy）（NCS）2] complex for their magnetic properties.It has been found that the complex（1,3） has ferromagnetic character while the others are antiferromagnetic in nature by using a broken symmetry approach in the DFT framework（BS-DFT） with support from the coupling constant values（J） and spin density plots.

Modulating the p-band center of carbon nanofibers derived from Co spin state as anode for high-power sodium storage

Carbon nanofibers(CNFs)have received extensive and in-depth studied as anodes for sodium-ion batteries(SIBs),and yet their initial Coulombic efficiency and rate capability remain enormous challenge at practical level.Herein,CNFs anchored with cobalt nanocluster(CNFs-Co)were prepared using chemical vapor deposition and thermal reduction methods.The as-prepared CNFs-Co shows a high initial Coulombic efficiency of 91%and a high specific discharge capacity of 246 mAh/g at 0.1 A/g after 200 cycles as anode for SIBs.Meanwhile,the CNFs-Co anode still delivers a high cycling stability with 108 mAh/g after 1000 cycles at 10 A/g.These excellent electrochemical properties could be attributed to the involved spin state Co,which endows CNFs with large interplanar spacing(0.39 nm)and abundant vacancy defects.Importantly,the spin state Co downshifts the p-band center of carbon and strengthens the Na+adsorption energy from-2.33 eV to-2.64 eV based on density functional theory calculation.This novel strategy of modulating the carbon electronic structure by the spin state of magnetic metals provides a reference for the development of high-performance carbon-based anode materials.

Neural network study of the nuclear ground-state spin distribution within a random interaction ensemble

The distribution of the nuclear ground-state spin in a two-body random ensemble(TBRE)was studied using a general classification neural network(NN)model with two-body interaction matrix elements as input features and the corresponding ground-state spins as labels or output predictions.The quantum many-body system problem exceeds the capability of our optimized NNs in terms of accurately predicting the ground-state spin of each sample within the TBRE.However,our NN model effectively captured the statistical properties of the ground-state spin because it learned the empirical regularity of the ground-state spin distribution in TBRE,as discovered by physicists.

Modulating the electronic spin state by constructing dual-metal atomic pairs for activating the dynamic site of oxygen reduction reaction

In this study,dual-metal atomic pairs of manganese(Mn)-iron(Fe)binuclear sites(BNSs)with two conjoint MnN4 and FeN4 moieties(MnFeN8)anchored onto a graphite-like structure(GLS)(Mn-Fe BNSs/GLS)were constructed.The binuclear MnFeN8 structure was verified experimentally and theoretically.Magnetic measurements and Gaussian calculations reveal that this unique Mn-Fe BNSs exhibit strong short-range electronic interaction between Mn and Fe sites,which decouples two paired d electrons in Fe sites,thereby transforming Fe sites from an intermediate to a high spin state.The optimal electronic configuration of Fe sites and their binuclear structure facilitate an oxygen reduction reaction(ORR)thermodynamically and dynamically,respectively,endowing Mn-Fe BNSs with improved ORR performance.

High spin states in stable nucleus ^(84)Sr

High spin states of 84Sr were populated through the reaction 70Zn(18O,4n)84Sr at 75 MeV beam energy.Measurement of excitation function,γ-γ coincidences,directional correlation from oriented state (DCO) ratios and γ-transition intensities were performed using eight anticompton HPGe detectors and one planar HPGe detector.Based on the measured results,a new level scheme of 84Sr was established in which 12 new states and nearly 30 new γ-transitions were identified in the present work.The positive-parity states of the new level scheme were compared with the results from calculations in the framework of the projected shell model (PSM).One negative-parity band was extended to spin Iπ=19-and it can be found that in the high spin states,the γ-transition energies show the nature of signature staggering.The negative-parity band levels are in good agreement with deformed configuration-mixing shell model (DCM) calculations.

Single-metal-atom site with high-spin state embedded in defective BN nanosheet promotes electrocatalytic nitrogen reduction

Single-atom catalysts (SACs) especially supported on two-dimensional nitrogen-doped carbon substrate have been widely reported to be able to effectively promote electrocatalytic N_(2) reduction reaction (eNRR). The precise design of single-metal-atom active site (SMAS) calls for fundamental understanding of its working mechanism for enhanced eNRR performance. Herein, by means of density functional theory calculations, we theoretically investigate the eNRR performance of nine prototypical SMAS, namely, MN_(2)B_(2) (M: transition metals of IIIB, IVB and VB groups) which comprises of asymmetric ligands of N_(2)B_(2) embedded in defective BN nanosheet. Our results reveal the significant role of spin state of SMAS in tuning the potential-determining steps of eNRR, in which MN_(2)B_(2) site with higher spin magnetic moment (μ) is beneficial to reducing limiting potentials (U_(L)) of eNRR. Specially, CrN_(2)B_(2) (μ = 4μB), VN_(2)B_(2) (μ = 3μB) and MoN_(2)B_(2) (μ = 2μB) demonstrate high activity and selectivity to eNRR. The asymmetric ligands of N_(2)B_(2) are deemed to be superior over mono-symmetric ligands. More importantly, our results demonstrate that breaking (or deviating) of the scaling relations between key N-containing intermediates (*N_(2)H/*N_(2) and *NH2/*N_(2)) on MN_(2)B_(2) can be realized by enhancing spin state of SMAS which renders the active site a balanced N-affinity critical for efficient eNRR. This observation is validated by the calculated Sabatier volcano-shape relation between eNRR limiting potentials and N_(2) adsorption energy. Our study develops the guidance for catalyst design to boost eNRR performance by tuning the spin state of an active site.