A comparative study of the structure and crystallization of bulk metallic amorphous rod Pr60Ni30Al10 and melt-spun metallic amorphous ribbon Al87Ni10Pr3

Pr-based bulk metallic amorphous （BMA） rods （Pr60Ni30Al10） and Al-based amorphous ribbons （Al87Ni10Pr3） have been prepared by using copper mould casting and single roller melt-spun techniques, respectively. Thermal parameters deduced from differential scanning calorimeter （DSC） indicate that the glass-forming ability （GFA） of Pr60Ni30Al10 BMA rod is far higher than that of Al87Ni10Pr3 ribbon. A comparative study about the differences in structure between the two kinds of glass-forming alloys, superheated viscosity and crystallization are also made. Compared with the amorphous alloy Al87Ni10Pr3, the BMA alloy Pr60Ni30Al10 shows high thermal stability and large viscosity, small diffusivity at the same superheated temperatures. The results of x-Ray diffraction （XRD） and transmission electron microscope （TEM） show the pronounced difference in structure between the two amorphous alloys. Together with crystallization results, the main structure compositions of the amorphous samples are confirmed. It seems that the higher the GFA, the more topological type clusters in the Pr-Ni-Al amorphous alloys, the GFAs of the present glass-forming alloys are closely related to their structures.

An amorphous manganese iron oxide hollow nanocube cathode for aqueous zinc ion batteries

Aqueous zinc ion batteries(ZIBs) are attracting considerable attentions for practical energy storage because of their low cost and high safety.Nevertheless,the traditional manganese oxide cathode materials suffer from the low intrinsic electronic conductivity,sluggish ions diffusion kinetics,and structural collapse,hindering their large-scale application.Herein,we successfully developed a latent amorphous Mn_(1.8)Fe_(1.2)O_(4) hollow nanocube(a-H-MnFeO) cathode material derived from Prussian blue analogue precursor.The amorphous nature endows the cathode with lower diffusion barrier and narrower band gap compared with crystalline counterpart,resulting in the superior Zn^(2+) ions and electrons transport kinetics.Hollow structure can furnish abundant surface sites and suppress the structural collapse during the repeated charge/discharge processes.By virtue of the multiple advantageous features,the a-H-MnFeO cathode exhibits exceptional electrochemical performance,in terms of high capacity,excellent rate capability,and prolonged cycle life.This strategy will pave the way for the structural design of emerging cathode materials.

Micromagnetic Structure of Co-Rich Amorphous Microwires

Results on the magneto-optical investigation of near-surface micromagnetic structure (MMS) of Co69Fe4Si12B15 amorphous wires 10～50 μm in diameter are presented. The wires were prepared by the rapid solidification technique. The magnetic field H was applied along or perpendicular to the wire length. By scanning the light spot of 1 μm-diameter along the wire length, distributions of magnetization components (both parallel and perpendicular to the applied magnetic field) and also local hysteresis characteristics of the wires were measured. It was experimentally established that owing to the compressive stresses from quenching coupled with negative magnetostriction of Co-rich amorphous materials, the examined microwires have a circumferential magnetic anisotropy. In consequence, there are the near-surface alternate left- and right-handled circular domains in these samples. The dependencies of the circular domain width on the wire diameter and length were found. It was discovered that in the axial magnetic field local hysteresis loops are unhysteretic. It was proved that in this case the dominant mechanism of the wire magnetization reversal is rotation of local magnetization vectors in circular domains.

Correlation between Structures of Bulk Amorphous Zr-Ti-Ni-Cu-Be Alloy in Different States

The structures of the bulk amorphous Zr41Ti14Cu12.5Nil0.0Be22.5 alloy have been analyzed in solid, supercooled liquid and liquid with X-ray diffraction. The first coordination sphere radii and the first coordination numbers are 0.312 um, 11.2 in solid state.10.932 nm, 10.932 in supercooled liquid region and 0.305 urn, 11.296 in liquid state. The structures are the same in different states. But it shows some tendency to crystallizing that the first coordination sphere radius and the first coordination number drop in supercooled liquid region.

Electrochemical deposited amorphous FeNi hydroxide electrode for oxygen evolution reaction

The electrodeposition approach is significant in electrode fabrication for practical application.Herein,the electrodeposited amorphous NiFe hydroxide species for oxygen evolution reaction (OER) in water splitting reaction is demonstrated by revealing the synergistic effect influenced by the support electrode of Fe and Ni foil and the contents of Fe and Ni in the electrolyte.All the electrodeposited samples have an amorphous structure and similar profiles of binding energy and chemical states for Fe and Ni as characterized by the spectroscopic techniques.While the support effect and Fe/Ni synergistic effect are indeed observed for the varied catalytic performances observed for the different electrodes;the Ni foil supported catalyst exhibits much higher performance than that of the Fe foil supported catalyst,and the different redox potentials of Ni species in the different Fe/Ni electrode resulting from the Fe–Ni synergism are observed in the cyclic voltammetry curve analysis.The surface roughness and the electrochemical surface area are also influenced by the support effect and the Fe/Ni ratio in the plating electrolyte.The optimal electrode shows a very low overpotential of~200 mV to reach 10 mA cm^(-2),and very high catalytic stability by the consecutive cyclic voltammetry measurements and 20 h stability test.Though it has the largest electrochemical surface area,the highest catalytic efficiency for these active sites is also indicated by the specific activity and turnover frequency polarization curves.The current work shows the effective experience for the electrodeposited Fe/Ni based catalysts in large-scale fabrication,which can be more practical for hydrogen generation in the alkaline water electrolysis.

Microstructures of Ti–Ni–Fe wire after severe cold-drawing and annealing

The microstructures and mechanical properties of Ti–47 at%Ni–3 at%Fe shape memory alloy wire under the condition of severe cold-drawing at room temperature and different postdeformation annealing processes were intensively investigated using transmission electron microscope(TEM),X-ray diffraction(XRD),Vickers microhardness tester and electron tensile tester.It is indicated that the structure of the alloy evolves into a predominant amorphous structure with a trace of nanocrystalline B2 phase after the cold-drawing of 76%areal reduction.Postdeformation annealing process exerted significant influence on the microstructure and mechanical properties.Crystallization occurs when the cold-drawn wire was annealed at 300℃ for 30 min.The ultimate tensile strength and ductility as well as the superelasticity of the wire are improved significantly by cold-drawing plus postdeformation annealing.

Amorphous NiO_(n)coupled with trace PtO_(x)toward superior electrocatalytic overall water splitting in alkaline seawater media

Developing corrosion resistance bifunctional electrocatalysts with high activity and stability toward both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),especially electrolysis in seawater,is of prime significance but still pressingly challenging.Herein,in-situ introduced PtO_(x)on the derivative amorphous NiO_(n)is prepared via heat treatment of Ni ZIFL nanosheets on nickel foam under low temperature(PtO_(x)-NiO_(n)/NF).The synthesized PtO_(x)-NiO_(n)/NF possesses suprahydrophilic and aerophilic surface,then in favor of intimate contact between the electrode and electrolyte and release of the generated gas bubbles during the electrocatalysis.As a result,the in-situ PtO_(x)-NiO_(n)/NF electrode presents outstanding bifunctional activity,which only requires extremely low overpotentials of 32 and 240 mV to reach a current density of 10 mA·cm^(-2)for HER and OER,respectively,which exceeds most of the electrocatalysts previously developed and even suppresses commercial Pt/C and RuO_(2)electrodes.As for two-electrode cell organized by PtO_(x)-NiO_(n)/NF,the voltages down to 1.57 and 1.58 V are necessary to drive 10 mA·cm^(-2)with remarkable durability in 1 M KOH and alkaline seawater,respectively,along with remarkable stability.Moreover,a low cell voltage of 1.88 V is needed to achieve 1,000 mA·cm^(-2)toward water-splitting under industrial conditions.This study provides a new idea for designing in-situ amorphous metal oxide bifunctional electrocatalyst with strong Pt–support interaction for overall water splitting.

Synergically improved energy storage performance and stability in sol–gel processed BaTiO_(3)/(Pb,La,Ca)TiO_(3)/BaTiO_(3) tri-layer films with a crystalline engineered sandwich structure

Achieving an excellent energy storage performance,together with high cycling reliability,is desirable for expanding technological applications of ferroelectric dielectrics.However,in well-crystallized ferroelectric materials,the concomitant high polarizability and low polarization saturation field have led to a square-shaped polarization–electric field loop,fatally impairing both recoverable energy density(W_(rec))and efficiency(η).Nanocrystalline ferroelectric films with a macroscopically amorphous structure have shown an improved W_(rec) andη,but their much lower polarizability demands an extremely high electric field to achieve such performances,which is undesirable from an economic viewpoint.Here,we propose a strategy to boost the energy storage performances and stability of ferroelectric capacitors simultaneously by constructing a tri-layer film in which a well-crystallized ferroelectric layer was sandwiched by two pseudo-linear dielectric layers with a dominant amorphous structure.In sol–gel-derived BaTiO_(3)/(Pb,La,Ca)TiO_(3)/BaTiO_(3)(BTO/PLCT/BTO)tri-layer films,we show that the above design is realized via rapid thermal annealing which fully crystallized the middle PLCT layer while left the top/bottom BTO cap layers in a poor crystallization status.This sandwiched structure is endowed with an enhanced maximum polarization while a small remnant one and a much-delayed polarization saturation,which corresponds to large W_(rec)≈80 J/cm^(3) and highη≈86%.Furthermore,the film showed an outstanding cycling stability:its W_(rec) andηremain essentially unchanged after 10^(9) electric cycles(DW/W<4%,Dη/η<2%).These good energy storage characteristics have proved the effectiveness of our proposed strategy,paving a way for the utilization of sandwiched films in applications of electric power systems and advanced pulsed-discharge devices.

Composition-dependent structural characteristics and mechanical properties of amorphous SiBCN ceramics by ab-initio calculations

The atomic structural features and the mechanical properties of amorphous silicoboron carbonitride ceramics with 13 different compositions in the Si–BN–C phase diagram are investigated employing ab-initio calculations.Both chemical bonds and local structures within the amorphous network relate to the elemental composition.The distribution of nine types of chemical bonds is composition-dependent,where the B–C,Si–N,Si–C,and B–N bonds hold a large proportion for all compositions.Si prefers to be tetrahedrally coordinated,while B and N prefer sp^(2)-like trigonal coordination.In the case of C,the tetrahedral coordination is predominant at relatively low C contents,while the trigonal coordination is found to be the main feature with the increasing C content.Such local structural characteristics greatly influence the mechanical properties of SiBCN ceramics.Among the studied amorphous ceramics,SiB_(2)C_(3)N_(2) and SiB_(3)C_(2)N_(3) with low Si contents and moderate C and/or BN contents have high elastic moduli,high tensile/shear strengths,and good debonding capability.The increment of Si,C,and BN contents on this basis results in the decrease of mechanical properties.The increasing Si content leads to the increment of Si-contained bonds that reduce the bond strength of SiBCN ceramics,while the latter two cases are attributed to the raise of sp^(2)-like trigonal configuration of C and BN.These discoveries are expected to guide the composition-tailored optimization of SiBCN ceramics.

Non-affinity:The emergence of networks from amorphous planar graphs

The primary research of physics is to reveal the underlying law of the physical world.However,for a complex system consisting of multiple components,even if we know every details of each component,we still cannot predict the collective behavior due to the emergence phenomenon.The amorphous networks of mass points hinged by springs belong to such a complex system.Owing to the non-affinity,one of the emergence phenomena of the network,the displacements field of the internal mass points under the external load tends to be chaotic,and there is no well-established theoretical framework to describe these points’collective behavior analytically.The non-affine mechanical responses of the amorphous networks are very common,whereas the affine response is rare and it occurs only in those lattices with one site per unit cell.The network’s non-affinity prevents us from further investigating the relationship between its intrinsic properties(such as the contact number,local structure,and topological characteristics)and the mechanical behaviors.As a result,it is very complicated and difficult to predict the responses of an amorphous network to an imposed strain.Interestingly,a sort of amorphous network derived from the jammed particles is reported to have almost perfect affine mechanical behavior,in a stark contrast with the general perception.These findings may shed light on uncovering the structural factors that affect the network’s affinity.This article will give a short review of the latest advances in this area.

Fabrication of amorphous FeCoNiCuMnP x high-entropy phosphide/carbon composites with a heterostructured fusiform morphology for efficient oxygen evolution reaction

Amorphous high-entropy materials with abundant defects,coordinatively unsaturated sites,and loosely bonded atoms could exhibit excellent electrocatalytic performance.However,how to fabricate such ma-terials with nanostructure as well as amorphous structure is still full of challenges.In this work,high-entropy metal organic framework(HE-MOF)is employed as the self-sacrificial template to fabricate FeCoNiCuMnP x high-entropy phosphide/carbon(HEP/C)composites.The obtained composite shows a het-erostructured fusiform morphology,in which the HEP is encapsulated by a carbon layer,revealing high electron conductivity as well as rich catalytic active sites for oxygen evolution reaction(OER).Beside,it is found that there is a short-range ordered crystal structure in the amorphous phase,which is bene-ficial for revealing high OER catalytic activity as well as good stability.As a result,the optimum HEP/C composite shows an overpotential 239 mV@10 mA cm^(−2)with a small Tafel slope of 72.5 mV dec^(−1) for catalyzing OER in alkaline solution.

Nanostructured Ti29.7Ni50.3Hf20 high temperature shape memory alloy processed by high-pressure torsion

High-pressure torsion(HPT)processing under a pressure of 6.0 GPa was applied to Ti29.7Ni50.3Hf20(at.%)alloy.Two types of structure were observed after HPT with 3 revolutions:first one is the mixture of amorphous phase and retained nanocrystalline;second is the alternating bands of amorphous phase and high defect density crystalline.As a result,post deformation annealing(PDA)at 500-700℃leads to the non-uniform distribution of martensite and parent phase grains.The grains of martensite are twice larger compared to that of parent phase.The nanocrystalline and ultrafine grains form after annealing at 500-600℃and 700℃,respectively.The twinning mechanism does not change with the reduction of martensitic grains up to^35 nm.The relationship between strength and grain size in Ti29.7Ni50.3Hf20 alloy obeys the classical Hall-Petch relationship with a coefficient of 10.80±0.39 GPa nm^1/2.

Amorphous Ni-Co-S nanocages assembled with nanosheet arrays as cathode for high-performance zinc ion battery

The selection and development of cathode of alkaline zinc batteries(AZBs)is still hindered and often leads to poor rate capability and short cycle life.Here,amorphous hollow nickel-cobalt-based sulfides nanocages with nanosheet arrays(AM-NCS)are designed and constructed with ZIF-67 as the selftemplate to exchange with Ni^(2+) and S^(2-) by using a two-step ion exchange method.The synthesized AM-NCS possess the high specific capacity(160 m Ah/g at 2 A/g),and the assembled battery has excellent rate performance(146 m Ah/g reversible capacity at 5 A/g).The assembled device has excellent rate performance(155 m Ah/g at 2 A/g)and long cycling stability(7000 cycles,62.5%of initial capacity).The excellent electrochemical properties of the electrode materials are mainly attributed to the unique structure,in particular,polyhedron structure with hollow structure can improve the cyclic stability,and the amorphous structure can expose more reactive sites on the surfaces of nickel,cobalt and sulfur.This work provides a new strategy for the design and fabrication of high performance cathode materials for AZBs.

Highly efficient and recyclable amorphous Pd(II)/crystal Pd(0)catalyst for boosting Suzuki reaction in aqueous solution

Ultrafine and highly dispersed Pd nanoparticles have drawn considerable attention with high activity,selectivity and atomic efficiency.In this paper,amorphous Pd(II)-complex solid spheres with-5 nm Pd nanoparticles loaded on were successfully achieved through a simple and gentle one-pot solution method with vitamin B1 simultaneously as complexing agent and reducing agent.An ultrathin mesoporous SiO_(2) shell was then coated at the surface of Pd(II-O)spheres as the armor which could prevent the dissolution of Pd(II)during the catalytic process.The combination of Pd(II)and Pd(0)endowed Pd(II-0)@m-SiO_(2) catalyst an excellent performance in eco-friendly aqueous media Suzuki reactions.The high activity,productivity and recyclability were all comparable with the best Pd catalysts ever reported.The ingenious formation of amorphous Pd(II)/crystal Pd(0)with enhanced catalytic performances provides a new,scalable strategy to practical promotion of Suzuki cross-coupling reactions.

Nanocrystallization of α-Fe Crystals in Fe_(52)Cr_(18)Mo_7B_(16)C_4Nb_3 Bulk Amorphous Alloy

Crystallization kinetics of Fe52Cr18Mo7B16C4Nb3 alloy was evaluated by X-ray diffraction（XRD）,differential scanning calorimetric（DSC） tests and transmission electron microscopy（TEM） observations in this research work.In effect,crystallization and growth mechanism were investigated by using DSC tests at four different heating rates（10,20,30,40 K/min）.Results showed that a two-step crystallization process occurred in the alloy in which α-Fe and Fe3B phases were crystallized,respectively in the structure after heat treatment.Activation energy for the first step of crystallization,i.e.α-Fe was measured to be 421 and 442 kJ/mol according to Kissinger-Starink and Ozawa models,respectively.Further,Avrami exponent calculated from DSC curves was 1.6 and a two-dimensional diffusion controlled growth mechanism with decreasing nucleation rate was observed in the alloy.Moreover,it was known from the TEM observations that crystalline α-Fe phase nucleated in the structure of the alloy in an average size of 10 nm and completely mottled morphology.

Tunable Atomic-Scale Steps and Cavities Break Both Stability and Activity Limits of CoO_(x) Nanosheets to Catalyze Oxygen Evolution

A highly active interface can enhance the catalytic efficiency of catalysts toward the oxygen evolution reaction(OER).However,accurately tuning their atomic interface configurations of defects with sufficient activity and stability remains a grand challenge.Herein,we report on breaking the activity and stability limits of CoO_(x) nanosheets in the OER process by constructing copious high-energy atomic steps and cavities,in which S or Ce atoms simultaneously replace O or Co atoms from CoO_(x),thus achieving high-energy atomic interface Ce,O-Co_(3)S_(4) nanosheets.By combining in situ characterization and density functional theory calculations,it is shown that the unique orbital coupling between Ce-4f,O(S)-2p,and Co-3d causes it to be closer to the Fermi level,leading to faster charge transfer capability.More importantly,the novel structure breaks the stability limit of cobalt sulfide with planar defects,which gives high catalytic activity and stability in 0.1 M KOH solutions,better than commercial RuO_(2) and IrO_(2) noble metal catalysts.As expected,Ce,O-Co_(3)S_(4) possesses much better turnover frequency activity(0.064 s^(-1))at an overpotential of 300 mV,which is ~7 times larger than that of Ce-CoO_(x)(0.009 s^(-1)).Our work presents a new perspective of designing catalysts with atomically dispersed orbital electronic coupling defects toward efficient OER electrocatalysis.

块体金属玻璃结构-动力学关联模拟研究的临界模型尺度

原子尺度模拟是当前理解金属玻璃体系的无序结构及其构效关系的有效方法.基于分子动力学模拟,本文以代表性金属玻璃Cu_(5)0Zr_(50)为研究对象,系统地研究了块体金属玻璃体系的原子结构和动力学行为的有限尺度效应.通过研究发现,其结构短程序对模型尺寸并不敏感,但其动力学性质却表现出明显的尺寸相关性.通过定量计算可知,当立方体模型所含原子数低于~2000时,金属玻璃体系的结构短程序特征和结构弛豫之间的相关性发生退简并,但其结构弛豫时间和动力学非均匀性依然遵循简并的普适关系.本文的结论给出了结构弛豫和动力学非均匀性之间存在本征关联的有力证据,并第一次明确给出了在没有表面效应的情况下基于计算模拟研究块体金属玻璃结构、动力学及其关联所需要的临界模型尺度.

Tunable ultrathin dual-phase P-doped Bi_(2)MoO_(6) nanosheets for advanced lithium and sodium storage

The construction of electrode materials for lithium-ion batteries(LIBs)and sodium-ion batteries(SIBs)has gradually been an appealing and attractive technology in energy storage research field.In the present work,a facile strategy of synthesizing ultrathin amorphous/nanocrystal dual-phase P-doped Bi_(2)MoO_(6)(denoted as P-BiMO)nanosheets via a one-step wet-chemical synthesis approach is explored.Quite distinct from conventional two-dimensional(2D)nanosheets,our newly developed ultrathin P-BiMO nanosheets exhibit a unique tunable amorphous/nanocrystalline dual-phase structure with several compelling advantages including fast ion exchange ability and superb volume change buffer capability.The experimental results reveal that our prepared P-BiMO-6 electrode delivers an excellent reversible capacity of 509.6 mA·g^(−1) after continuous 1,500 cycles at the current densities of 1,500 mA·g^(−1) and improved rate performance for LIBs.In the meanwhile,the P-BiMO-6 electrode also shows a reversible capacity of 300.6 mA·g^(−1) after 100 cycles at 50 mA·g^(−1) when being used as the SIBs electrodes.This present work uncovers an effective dual-phase nanosheet structure to improve the performance of batteries,providing an attractive paradigm to develop superior electrode materials.

Serration and Noise Behavior in Advanced Materials

The Chinese Materials Research Society（C-MRS）Conference（2015）was held in the Guizhou Park Hotel International Conference Center,Guiyang,China,from July 10-14,2015.This conference consists of 30symposia,including 4international symposia.As one of 4international symposia,＂Serration and noise behavior in advanced materials＂