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The presence of Al and Si impurities from ultrapure magnetite concentrate (UMC) entering the lattice during the preparation of M-type strontium ferrite (SrM) has been a significant issue limiting the enhancement of magnetic properties in UMC- prepared SrM. In this article, the impact of CaCO 3 on the phase formation mechanism of synthesizing SrM using UMC is investigated. It is found that the formation of intermediate SrFeO 3−x phase and SrFe 12 O 19 phase shifts to the lower temperatures upon CaCO 3 addition. Lower calcination temperatures can inhibit excessive grain growth, thereby improving coercivity. At a calcination temperature of 1050 °C with the addition of 0.6 wt% CaCO 3 , the highest coercivity of 4672.29 Oe was achieved. Lattice parameters, magnetic properties, and micro-area composition analysis demonstrate that the addition of CaCO 3 reacts with Al impurities, preventing the incorporation of Al ions into the SrM lattice and promoting an increase in saturation magnetization. The highest saturation magnetization of 71.45 emu/g was obtained at the calcination temperature of 1200 °C. It has reached the level of magnetic properties of SrM prepared from Fe 2 O 3. CaCO 3 , being low-cost and environmentally friendly, can serves as an effective additive for improving the magnetic properties of UMC-prepared SrM without compromising its cost-effective and eco-friendly advantages. • SrFe 12 O 19 was synthesized from ultrapure magnetite concentrate as raw materials. • Adding CaCO 3 reduces the formation temperature of intermediate and final phases. • Adding CaCO 3 weakens the adverse effect of Al impurity of raw materials. • Adding CaCO 3 improves the magnetic properties of synthesized SrFe 12 O 19. • SrFe 12 O 19 is produced cheaply and environmentally. [ABSTRACT FROM AUTHOR]

Aqueous Zn ion batteries with cost-effectiveness, high safety, and eco-friendliness have a great potential as an excellent substitute for non-aqueous cells for large-scale energy storage. However, the intercalation of Zn2+ ions in the cathode materials is challenging and complex due to the sluggish diffusion kinetics of Zn2+ ions. Herein, the highly reversible Zn ion battery based on vanadium oxide nanobelts has been developed by using pre-inserted bimetallic ions (Na+ and Ca2+ ions) within the vanadium oxide layer (NCVO) as the cathode and Zn(CF 3 SO 3) 2 solution as an electrolyte. Vanadium oxide nanobelts which were calcined at 350 °C (NCVO-350) deliver the superior cycle stability with a capacity retention rate close to 100% after 200 cycles at 0.5 A g−1, and 92% retention is also achieved after 3000 cycles at 10 A g−1. The ultrahigh capacity retentions at low/high current densities are attributed to the pre-inserted bimetallic ions within the layers to enhance the structural stability of the vanadium oxide nanobelts. Moreover, the low-cost electrode material preparation process will accelerate the industrialization of aqueous Zn ion batteries. [Display omitted] • A simple solution impregnation method at ambient conditions is proposed. • The conversion of vanadium-based materials from nanoparticles to nanobelts. • Amorphous structure of electrode also can enhance Zn-storage performances. • Bimetallic ions nanobelts exhibit promising electrochemical performance. [ABSTRACT FROM AUTHOR]

Anisotropic strength and ductility are limiting factors for the application of laser powder bed fusion AlSi10Mg. Previous efforts were devoted to explaining the origins of anisotropy mainly from the geometrical orientations of the Al-Si cellular structure and melt pool border, but the effect of crystallographic orientation is still unexplored. The present work aims to assess the mechanical behavior of Al-Si cellular structure using crystal plasticity model, with a focus on how grain orientation affects strength, damage initiation and their anisotropy. Forty-four crystallographic orientations were generated and assigned to a representative volume element resembling the real Al-Si cellular structure. For each orientation, simulations of uniaxial tension along the building direction and the perpendicular direction were performed. It is found that the grain orientation has a huge influence on both strength and damage sensitivity. Nevertheless, the correlation between strength and orientation cannot be established with the Schmid or Taylor factors due to the influence of the elongated Si network. Comparing the results for the two loading directions, strength anisotropy is revealed to present a weak dependence on grain orientation, whereas damage anisotropy varies significantly in the orientation space. The findings of this work can be used for up-scale modeling of mechanical behavior of additively manufactured AlSi10Mg. • Grain orientation affects notably strength and damage of Al-Si cellular structure. • Phase stress partition varies moderately in the grain orientation space. • Anisotropy in strength and damage show weak and strong dependences on orientation. [ABSTRACT FROM AUTHOR]

• The relative density and fraction of Cu-centered full icosahedron clusters decrease and then saturate with increasing irradiation dose. • The ultimate tensile strength of the irradiated MGs has a positive linear dependence with the relative density. • With increasing the dose level, the MG deformation mode switches from plastic instability to ductile necking and finally to homogenous plastic flow. • Two atomic-scale mechanisms responsible for the increase of irradiation-induced ductility and softening are unveiled. The irradiation induced variations in microstructure and mechanical properties of the Cu 64 Zr 36 metallic glasses (MGs) are investigated via large-scale molecular dynamics simulations. The irradiation condition is modeled by sequential and prolonged collision cascades. The simulation results show a simultaneous decrease of the density and the fraction of Cu-centered full icosahedron (CCFI) clusters in the irradiated samples. This microstructural evolution induced by the prolonged irradiation is proposed to be responsible for the change of deformation mode of tested samples under uniaxial tensile loading. When increasing the irradiation dose, the ultimate tensile strength of MG samples decreases gradually, while their deformation mechanism switches from localized shear banding to ductile necking and finally to ideally plastic flow, enhancing the MG ductility. Careful atomic-scale examinations on the initiation and development of shear transformation zones (STZs) are carried out for a better understanding of the irradiation-induced ductility enhancement in MGs. Two related effects of the irradiation are unveiled. On the one hand, the irradiation releases the stored strain energy by promoting the STZ activation within the MG matrix. On the other hand, the irradiation damages restrain the propagation of shear band through the innovatively proposed two-unit "STZ-vortex" mechanism. Under the combined effect of these two mechanisms, the low-temperature ductility of irradiated MGs is improved and the brittle-like failure driven by single shear banding is prevented. [ABSTRACT FROM AUTHOR]

Two crucial elements that aid in the development of supercapacitors are the usage of distinctive components and the creation of optimal structures. In view of this, polyphenylene sulfide (PPS) non-woven fibers prepared by melt-blast process are used as carbon precursor, and oxidized polyphenylene sulfide (O-PPS) was prepared by an innovative and environmentally friendly oxidation method, which overcame the melting and shrinkage of PPS at high temperatures. After carbonization, flexible carbon fibers (SCFs) with high specific surface area were formed by O-PPS. Then, polypyrrole (PPy) and metal-organic framework material (Co-MOF) are successively grown on the SCFs, and the Co-MOF is transformed into layered double hydroxide (NiCo-LDH) ultra-thin nanosheets (ca. 4 nm) with rich electrochemical active sites under nickel nitrate etching, which obtains the "skin-core" structure composite electrode. This materials' high specific capacitance of 1705.6 F g−1 at 1 A g−1, and the electrode reaction process is governed by the pseudocapacitance characteristic. Asymmetric supercapacitors assembled with porous carbon possesses 46.96 Wh kg−1 at 725 W kg−1, and the capacitance retention rate is 81.47% after 8500 cycles. This research provides a new combination of ultra-thin NiCo-LDH nanosheets with carbon fiber for energy storage while improving the energy density of supercapacitors. [Display omitted] • A greener and milder polymer oxidation process. • This material owns "skin-core" structure with ultra-thin nanosheet loaded. • The assembled asymmetric supercapacitor exhibits superior capacitance behavior. [ABSTRACT FROM AUTHOR]

Due to the chemical disorder in the multi-principal component alloy, the stacking fault energy (SFE) of high entropy alloy is greatly affected by the complex local elemental environment, thus invalidating the traditional SFE calculation approach. Herein, a novel strategy for localized stacking fault energy (LSFE) calculation is proposed, which can not only reasonably incorporate the local chemical fluctuation effect in HEAs but also allows to realize high-throughput SFE calculations. Based on statistical method, the quantitative probability distributions of SFEs in FCC and BCC HEAs are achieved, which are necessary for further study of dislocation motion and up-scale modeling of HEAs. Finally, the intrinsic correlation between the LSFE and the local composition inhomogeneity in HEAs is unprecedentedly established with the machine learning (ML) methods. By classifying the features, the main factors that affect the LSFE are revealed, which can provide significant guidance for the composition optimization of HEAs. [Display omitted] • A novel strategy is proposed for the localized stacking fault energy (LSFE) calculation in HEAs. • Based on statistical method, the quantitative probability distributions of SFEs in HEAs are achieved. • The intrinsic correlation between the LSFE and the local composition inhomogeneity is established using the ML method. • The bond-based features are classified to correlate the different levels of LSFEs, which is promising to guide the design of HEA. [ABSTRACT FROM AUTHOR]

Vacancies can easily capture H atoms in metals, forming hydrogen-vacancy complexes/clusters. In this work, the hydrogen-vacancy interactions in CoCrFeMnNi high-entropy alloy (HEA) were studied with first-principles calculations based on the density functional theory (DFT). The special quasi-random structure (SQS) method was used to construct a chemically disordered HEA, and the effects of solute H atoms on the formation energy of monovacancy, the formation energy and binding energy of multi-vacancy cluster were calculated. It is found that an H atom prefers to occupy an octahedral interstitial site neighboring a vacancy and attracts the charge from the surrounding first-nearest neighbor atoms (e.g. Co, Ni, Fe or Mn atom, excluding Cr atom), weakening the stability of the atoms around the vacancy and reducing the vacancy formation energy in CoCrFeMnNi HEA. After introducing H atoms, the formation energies of both vacancy and vacancy cluster decrease in CoCrFeMnNi HEA, but they are still higher than those in pure Fe and Ni. In addition, the reduction of the binding energy of vacancies in CoCrFeMnNi HEA is much lower than that in pure Fe and Ni, and the binding energy of vacancies even increases in some cases. The results of the first-principles calculations indicate that the solute hydrogen atoms, although promoting vacancies, unfavorably combining vacancies into clusters to form micro-voids. This provides a good explanation for the good resistance to hydrogen embrittlement of CoCrFeMnNi HEA observed in experiments. [Display omitted] • The vacancy formation energy reduction in HEA was revealed by the preferred site and electronic structure of a trapped H atom. • The effect of trapped H on the formation and growth process of multi-vacancy clusters in HEA was found. • The experimental phenomenon of HE in HEA was explained by first-principles calculations on H-vacancy interactions. [ABSTRACT FROM AUTHOR]

• Acid etching and NH 3 activation exposed more homodispersed Fe-N x -C active sites. • Fe-PCNRs-700 has a hierarchical porous structure and huge specific surface area. • Fe-PCNRs-700 exhibits excellent ORR activity in acidic and alkaline media. • Zn-air batteries are assembled with high power density and robust stability. Acid etching and NH 3 activation can not only increase the specific surface area of the catalyst, but also expose more Fe–N x –C active sites. Finally, the prepared Fe-PCNRs-700 exhibited excellent ORR activity and Zn-air battery performance. [Display omitted] Decorating porous carbon nanomaterials with rich homodispersed metal cluster and heteroatoms can effectively shorten the diffusion pathway of oxygen and expose more active sites, thereby promoting oxygen reduction reaction (ORR). Herein, hierarchical porous carbon nanorods with homodispersed Fe–N x –C active sites are obtained by calcination, etching and ammonia activation of Fe-nitrogenous acid (NTA) coordination polymer nanowires. The obtained Fe-PCNRs-700 as ORR catalysts show the excellent activity with half wave potential (E 1/2) of 0.71 V vs. reversible hydrogen electrode (RHE) in 0.5 M H 2 SO 4 and 0.87 V vs. RHE in 0.1 M KOH electrolyte, which owe to its huge specific surface area (1652 m2 g−1), hierarchical pore structure, homodispersed Fe–N x –C active sites and structural defects. Furthermore, using Fe-PCNRs-700 as a cathode catalyst in both liquid and flexible solid Zn-air batteries, and the assembled liquid batteries display the high power density of 161 mW cm−2 and robust charge/discharge stability of 116 h. [ABSTRACT FROM AUTHOR]