The disorder effect on the performance of novel waveguides constructed in two-dimensional amorphous photonic materials

On the basis of two-dimensional amorphous photonic materials, we have designed a novel waveguide by inserting thinner cylindrical inclusions in the centre of basic hexagonal units of the amorphous structure along a given path. This waveguide in amorphous structure is similar to the coupled resonator optical waveguides in periodic photonic crystals. The transmission of this waveguide for S-polarized waves is investigated by a multiple-scattering method. Compared with the conventional waveguide by removing a line of cells from amorphous photonic materials, the guiding properties of this waveguide, including the transmissivity and bandwidth, are improved significantly. Then we study the effect of various types of positional disorder on the functionality of this device. Our results show that the waveguide performance is quite sensitive to the disorder located on the boundary layer of the waveguide, but robust against the disorder in the other area in amorphous structure except the waveguide border. This disorder effect in amorphous photonic materials is similar to the case in periodic photonic crystals.

Magnetothermal Analysis of Nanocrystallization of Amorphous and Relaxations of Nanocrystalline Materials

For a few years it has been realized that nanocrystalline phases can be formed during crystallization of amorphous alloys annealed isothermally below the crystallization temperature of usual heating experiments. Data of this transformation monitored by the measurement of magnetic susceptibility are presented. A method using a magnetic balance with electronic stabilisation and combined computer facilities is applied. Constant heating and cooling rates as well as isothermal heat treatments are used. Magnetic measurements are able to detect the onset of the transformation of amorphous NI-P alloys much earlier than was possible with differential scanning calorimetry. The transformation kinetics can be analyzed by means of the Avrami plot based on the Johnson-Mehl-Avrami equation. The kinetics of solid state reactions in the nanostructured material can be investigated similarly. Formation of a Ni-phase in a nanostructured Hf-Ni alloy could be detected in a very early stage, where calorimetric methods are not sensitive. Segregation phenomena could be detected from the experiments even after long time. The sensitivity of the applied method is not dependent on the heating rate as the sensitivity of scanning calorimetry is.

Amorphous MoS_(3) enriched with sulfur vacancies for efficient electrocatalytic nitrogen reduction

Developing low-priced,yet effective and robust catalysts for the nitrogen reduction reaction(NRR) is of vital importance for scalable and renewable electrochemical NH3 synthesis.Herein,we provide the first demonstration of MoS_3 as an efficient and durable NRR catalyst in neutral media.The prepared amorphous MoS_3 naturally possessed enriched S vacancies and delivered an NH3 yield of 51.7 μg h^(-1) mg^(-1)and a Faradaic efficiency of 12.8% at-0.3 V(RHE) in 0.5 M LiClO_4,considerably exceeding those of MoS_2 and most reported NRR catalysts.Density functional theory calculations unraveled that S vacancies involved in MoS_3 played a crucial role in activating the NRR via a consecutive mechanism with a low energetics barrier and simultaneously suppressing the hydrogen evolution reaction.

Crystallization kinetics of (Ni_(0.75)Fe_(0.25)_(78-x)Nb_xSi_(10)B_(12)(x=0,5)amorphous alloys

Amorphous ribbons of （Ni0.75Fe0.25）78-xNbxSi10B12 （x = 0, 5） were prepared by a single roller melt-spinning technique in air atmosphere. The crystallization kinetics of the alloys were investigated by means of continuous heating, and the activation energies of the alloys were calculated using Kissinger plot method and Ozawa plot method on the basis of differential thermal analysis data. The crystallization products were analyzed by X-ray diffraction. After the （Ni0.75Fe0.25）78Si10B12 amorphous alloy was annealed at the temperatures 715 and 745 K, a single phase of γ-（Fe, Ni） solid solution with grain sizes of about 10.3 and 18.5 nm, respectively, precipitates in the amorphous matrix. The crystallized phases are γ-（Fe, Ni） solid solution, Fe2Si, Ni2Si, and Fe3B after annealing at 765 K. The （Ni0.75Fe0.25）73NbsSi10 B12 amorphous alloy was annealed at 720, 750, and 800 K; and the crystallization phases, γ（Fe, Ni） solid solution, （Fe, Ni）23B6. Ni31Si12 and Nb2NiB0.16 form simultaneously.

Accurate prediction method for the microstructure of amorphous alloys without non-metallic elements

A new structural parameter of amorphous alloys called atomic bond proportion was proposed, and a topological algorithm for the structural parameter was proven feasible in the previous work. In the present study, a correction factor, λ,is introduced to optimize the algorithm and dramatically improve the calculation accuracy of the atomic bond proportion.The correction factor represents the ability of heterogeneous atoms to combine with one another to form the metallic bonds and it is associated with the uniformity of the master alloy, mixing enthalpy, cooling rate during preparation, and annealing time. The correction factor provides a novel pathway for researching the structures of the amorphous alloys.

CRYSTALLIZATION KINETICS OF Al83Y10Ni7(at％) AMORPHOUS ALLOYS

Crystallization kinetics of Al83Y10Ni7(at%) amorphous alloys prepared bymelt spinning was studied by differential scanning calorimetry (DSC). Three or fourstages of transforniation from amorphous to equilibrium state can be distinguished atheating rate 1 ￣ 40K / min. Apparent activation energies are calculated according to themethods of Kissinger, Ozawa and Arrhernius equation. An amoaphous phase with highstructural and heat stability was obtained in the vicinity of Al83Y10,Ni7. The isotheimalcrystallization kinetics of the first peak, in the range of 0. 15￣ 0.85, was found to be inagreement with John-Mell-Avrami equation with n = 2.5. Nucleation and growth dur-ing isothennal crystallization of the first stage for Al83Y10Ni7 amorpohous were ap-proached by introducing the concept of local Avrami exponent and local activation en-ergy.

Curie Temperature of Amorphous Fe-Si-B and Fe-W-Si-B Alloys

オhe effects of composition, annealing temperature and time, annealing heating rate on the Curie temperature of amorphous FeSiB and FeWSiB alloys were studied. The results indicate that the Curie temperature of these alloys increases with the increase of the metalloid content when it is <25 at%, then decreases with the further increase of the metalloid content. For amorphous FeSiB and FeWSiB alloys with the low metalloid content, the Curie temperature increases with the annealing temperature and the annealing time. However, for the amorphous FeWSiB alloys with the high metalloid content, the Curie temperature increases at low annealing temperature and with short annealing time, and decreases at high annealing temperature and with long annealing time. The heating rate in measuring Curie temperature also influences the Curie temperature of the alloys. The Curie temperature is higher at lower heating rates.

MONTE-CARLO SIMULATION FOR ATOMIC DEPOSITION OF AMORPHOUS ELECTROLESS Ni_(80)P_(20) COATING

Atomic growth process and structure of Amorphous Electroless Coating have been studied, using Monte-Carlo simulation method. The simulation results of amorphous Ni80P20 coating show that PDFs are in accordance with practical values. The migrations of adatoms in coating's growth are different from that of solidification of amorphous materials. In some cases, the migrated adatoms in the process of growth of amorphous coating are not enough to occupy all vacancies and traps, so the amorphous coating is micro-porous. The immovable probability k and the largest migration distance of adatoms, which lie on the electroless bath components, affect the PDF, volume density and microporosity remarkably.

AN INCREMENTAL METHOD OF X-RAY DIFFRACTION QUANTITATIVE PHASE ANALYSIS OF SAMPLESCONTAINING AMORPHOUS MATERIAL

A new method for quantitative X-ray diffraction phase analysis of a powder misture has been developed according to Popovic's doping method. The weight fraction of amorphous material in the analysed sample is obtained. For a multicomponent system in which (n-2) pure phases are added into an n-phase compnent sample and theweight fractions of all n phases can be determined by the method. The test results of confirmation agree well with the theory.

Amorphous phosphorus chalcogenide as an anode material for lithiumion batteries with high capacity and long cycle life

The ever-increasing demands for modern energy storage applications drive the search for novel anode materials of lithium(Li)-ion batteries(LIBs) with high storage capacity and long cycle life, to outperform the conventional LIBs anode materials. Hence, we report amorphous ternary phosphorus chalcogenide(aP_(4)SSe_(2)) as an anode material with high performance for LIBs. Synthesized via the mechanochemistry method, the a-P_(4)SSe_(2) compound is endowed with amorphous feature and offers excellent cycling stability(over 1500 mA h g^(-1) capacity after 425 cycles at 0.3 A g^(-1)), owing to the advantages of isotropic nature and synergistic effect of multielement forming Li-ion conductors during battery operation. Furthermore,as confirmed by ex situ X-ray diffraction(XRD) and transmission electron microscope(TEM), the a-P_(4)SSe_(2)anode material has a reversible and multistage Li-storage mechanism, which is extremely beneficial to long cycle life for batteries. Moreover, the autogenous intermediate electrochemical products with fast ionic conductivity can facilitate Li-ion diffusion effectively. Thus, the a-P_(4)SSe_(2)electrode delivers excellent rate capability(730 mA h g^(-1)capacity at 3 A g^(-1)). Through in situ electrochemical impedance spectra(EIS) measurements, it can be revealed that the resistances of charge transfer(R_(SEI)) and solid electrolyte interphase(R_(Ct)) decrease along with the formation of Li-ion conductors whilst the ohmic resistance(R_(Ω)) remains unchanged during the whole electrochemical process, thus resulting in rapid reaction kinetics and stable electrode to obtain excellent rate performance and cycling ability for LIBs. Moreover, the formation mechanism and electrochemical superiority of the a-P_(4)SSe_(2)phase, and its expansion to P_(4)S_(3-x)Se_(x)(x = 0, 1, 2, 3) family can prove its significance for LIBs.

An amorphous FeMoO_(4) nanorod array enabled high-efficiency oxygen evolution electrocatalysis in alkaline seawater

The development of highly efficient and durable oxygen evolution reaction(OER)catalysts for seawater electrolysis is of great importance for applications.Here,an amorphous FeMoO_(4) nanorod array on Ni foam is reported as a highly active OER electrocatalyst in alkaline seawater,requiring only overpotentials of 303 and 332 mV to achieve 100 and 300 mA·cm^(-2),respectively.Moreover,it shows strong long-term electrochemical durability for at least 50 h.

Effects of rare-earth elements on the glass-forming ability and mechanical properties of Cu_(46)Zr_(47-x)Al_7M_x(M = Ce,Pr,Tb,and Gd) bulk metallic glasses

Cu46Zr47-xA17Mx （M = Ce, Pr, Tb, and Gd） bulk metallic glassy （BMG） alloys were prepared by copper-mold vacuum suction casting. The effects of rare-earth elements on the glass-forming ability （GFA）, thermal stability, and mechanical properties of Cu46Zr47-xA17Mx were investigated. The GFA of Cu46Zr47-xA17Mx （M = Ce, Pr） alloys is dependent on the content of Ce and Pr, and the optimal content is 4 at.%. Cu46Zr47-xA17Thx（X = 2, 4, and 5） amorphous alloys with a diameter of 5 mm can be prepared. The GFA of Cu46Zr47-xA17Gdx（x = 2, 4, and 5） increases with increasing Gd. Tx and Tp of all decrease. Tg is dependent on the rare-earth element and its content. ATx for most of these alloys decreases except the Cu46Zra2Al7Gd5 alloy. The activation energies △Eg, △Ex, and △Ep for the Cu46Zr42A17Gd5 BMG alloy with Kissinger equations are 340.7, 211.3, and 211.3 kJ/mol, respectively. These values with Ozawa equations are 334.8, 210.3, and 210.3 kJ/mol, respec- tively. The Cu46Zr45Al7Tb2 alloy presents the highest microhardness, Hv 590, while the Cu46Zr43A17Pr4 alloy presents the least, Hv 479. The compressive strength （at.f.） of the Cu46Zra3A17Gd4 BMG alloy is higher than that of the Cu46Zr43Al7Tb4 BMG alloy.

High performance of multi-layered alternating Ni-Fe-P and Co-P films for hydrogen evolution

Judiciously engineering the electrocatalysts is attractive and challenging to exploit materials with high electrocatalytic performance for hydrogen evolution reaction.Herein,we successfully perform the interface engineering by alternately depositing Co±P and Ni±Fe±P films on nickel foam,via facile electroless plating and de-alloying process.This work shows that there is a significant effect of de-alloying process on alloy growth.The electronic structure of layered alloys is improved by interface engineering.The multilayer strategy significantly promotes the charge transfer.Importantly,the Co±P/Ni±Fe±P/NF electrode fabricated by interface engineering exhibits excellent electrocatalytic hydrogen evolution activity with an overpotential of 43.4 mV at 10 mA cm^(-2)and long-term durability for 72 h in alkaline medium(1 mol L^(-1)KOH).The innovative strategy of this work may aid further development of commercial electrocatalysts.

Upconversion luminescence properties of Er^(3+) doped GeS_2-Ga_2S_3-KCl chalcohalide glasses

Er^3＋ ions doped chalcohalide glasses with the composition of 56GeS2-24Ga2S3-20KCl were fabricated by a melt-quenching method.Under 800 nm laser excitation,strong green emissions centered at 525 nm and 550 nm and weak red emission centered at 660 nm were observed,which were assigned to ^2H11/2→^4I15/2,^4S3/2→^4I15/2,and ^4F9/2→^4I15/2 transitions,respectively.The intensity reached maximum when the Er^3＋ ions concentration was 0.1 mol%.The possible upconversion luminescence mechanism was proposed from the discussion on the above results as well as the results of lifetimes of the metastable ^4I13/2 level and local environment of Er^3＋ ions.It is found that chalcohalide glass can be good host materials for upconversion luminescence.

Effect of cooling rate on the magnetic properties of Fe_(53)Nd_(37)Al_(10) alloy

The effect of cooling rate on the magnetic properties of the Fe53Nd37Al10 alloy prepared by different methods, i.e., suction casting and melt spinning at different rates, was investigated. The Fe53Nd37Al10 ribbon at the wheel speed of 5 m.s-1 exhibits the highest coercivity in the samples. Two hard magnetic phases are detected from the hysteresis loops of the 5 m.s-1 ribbon at all temperatures below room temperature. Their appearance is associated with different exchange coupling interactions, which are between the two kinds of hard magnetic phases or between the hard magnetic phase and the soft magnetic phase.

The increasing of localized free volume in bulk metallic glass under uniaxial compression

Using transmission electron microscopy and electron diffraction, we have investigated the microstructure of a Zr55Al10Ni5Cu30 bulk metallic glass under a uniaxial compression until a failure occurs at room temperature. It is shown that the amorphous structure has changed locally in the vicinity of the failure plane after the plastic deformation. An increase in free volume is observed within the localized areas due to the concentration of plastic flow, suggesting that the increasing of local free volume dominates the deformation mechanism of the metallic glass. The effect of free volume on the ＇serrated flow＇ behaviour in the stress-strain curves during the uniaxial compression is discussed.

Crystallization evolution and relaxation behavior of high entropy bulk metallic glasses using microalloying process

The role of the microalloying process in relaxation behavior and crystallization evolution of Zr_(20) Cu_(20) Ni_(20) Ti_(20) Hf_(20) high entropy bulk metallic glass(HEBMG) was investigated. We selected Al and Nb elements as minor elements, which led to the negative and positive effects on the heat of mixing in the master HEBMG composition, respectively. According to the results, both elements intensified β relaxation in the structure;however, α relaxation remained stable. By using different frequencies in dynamic mechanical analysis, it was revealed that the activation energy of β relaxation for the Nb-added sample was much higher, which was due to the creation of significant structural heterogeneity under the microalloying process. Moreover, it was found that Nb addition led to a diversity in crystallization stages at the supercooled liquid region.It was suggested that the severe structural heterogeneity in the Nb-added sample provided multiple energy-level sites in the structure for enhancing the crystallization stages.

Synthesis and magnetic properties of Fe_(100-x)Mo_x alloy nanowire arrays

The Fel00-xMox （13≤x ≤25） alloy nanowire arrays are synthesized by electrodeposition of Fe^2＋and Mo^2＋ with different ionic ratios into the anodic aluminum oxide templates. The crystals of Fel00-xMox alloy nanowires gradually change from polycrystalline phase to amorphous phase with the increase of the Mo content and the nanowires are of amorphous structure when the Mo content reaches 25 ate, which are revealed by the X-ray diffraction and the selected area electron diffraction patterns. As the Mo content increases, the magnetic hysteresis loops of Fel00-xMoz alloy nanowires in parallel to the nanowire axis are not rectangular and the slopes of magnetic hysteresis loops increase. Those results indicate that the magnetostatic interactions between nanowires and the magnetocrystalline anisotropy both have significant influences on the magnetization reversal process of the nanowire arrays.

Improvement of giant magneto impedance of Co-rich melt extraction wires by stress-current annealing

In order to improve the giant magneto impedance （GMI） of Co-rich wires for high sensitive sensor applications, Co6sFe4.sSilsBlz5 wires were prepared by melt an extraction technique and subjected to Joule stress-current anneal treatments with different tensile slresses applied. And then their GMI response was investigated at a frequency range from 0.1 to 13 MHz. It was found through the comparison of results that the GMI effect of these wires had been improved through stress-current anneal treatments, because the tensile stress applied on these Co-rich wires introduced magnetoelastic energy and increased anisotropy, which improved the circular permeability and GMI effect. Their impedance ratio AZ/Z increased from 244% to 480.9% at 7 MHz and the field sensitivity increased to 0.83%/（A/m） at 5 MHz, when a tensile stress of 244 MPa was applied at an anneal current of 100 mA for 10 min. It was therefore concluded that these annealed wires were suitable for high sensitive sensor applications.

Serrated magnetic properties in metallic glass by thermal cycle

Fe-based metallic glasses（MGs） with excellent soft magnetic properties are applicable in a wide range of electronic industry. We show that the cryogenic thermal cycle has a sensitive effect on soft magnetic properties of Fe78Si9B13 glassy ribbon. The values of magnetic induction（or magnetic flux density） B and Hc coercivity c show fluctuation with increasing number of thermal cycles. This phenomenon is explained as thermal-cycle-induced stochastically structural aging or rejuvenation which randomly fluctuates magnetic anisotropy and, consequently, the magnetic induction and coercivity. Overall,increasing the number of thermal cycles improves the soft magnetic properties of the ribbon. The results could help understand the relationship between relaxation and magnetic property, and the thermal cycle could provide an effective approach to improving performances of metallic glasses in industry.