Influence of Hydrothermal Synthesis Conditions on the Formation of Calcium Silicate Hydrates:from Amorphous to Crystalline Phases

Hydrothermal treatment has been widely applied in the synthesis of well crystalline calcium silicate hydrate（CSH）, such as tobermorite and xonotlite. However, both morphology and crystallinity of CSH are greatly affected by the conditions of hydrothermal treatment including siliceous materials, temperature increase rate and isothermal periods. In this study, the influence of hydrothermal conditions on the growth of nano-crystalline CSH was investigated based on XRD analysis. Results showed that siliceous materials with amorphous nature（i e, nano silica powder） are beneficial to synthesize pure amorphous CSH, while the use of more crystallized siliceous materials（i e, diatomite and quartz powder） leads to producing crystalline CSH. Results also indicate that the formation of tobermorite and xonotlite is greatly affected by the temperature rise rate during hydrothermal treatment.

Effect of amorphous lamella on the crack propagation behavior of crystalline Mg/amorphous Mg–Al nanocomposites

The effects of amorphous lamella on the crack propagation behavior in crystalline/amorphous（C/A） Mg/Mg–Al nanocomposites under tensile loading are investigated using the molecular dynamics simulation method. The sample with an initial crack of orientation（1210） [0001] is considered here. For the nano-monocrystal Mg, the crack growth exhibits brittle cleavage. However, for the C/A Mg/Mg–Al nanocomposites, the ‘double hump＇ behavior can be observed in all the stress–strain curves regardless of the amorphous lamella thickness. The results indicate that the amorphous lamella plays a critical role in the crack deformation, and it can effectively resist the crack propagation. The above mentioned crack deformation behaviors are also disclosed and analyzed in the present work. The results here provide a strategy for designing the high-performance hexagonal-close-packed metal and alloy materials.

Crystallization of Fe_(78)Si_9B_(13) Bulk Crystaline/ Amorphous(c/a) Composite

A metallic crystalline/amorphous （c/a） bulk composite was prepared by the slow cooling method after remelting the amorphous Fe78Si9B13 ribbon. By X-ray diffraction （XRD）, differential scanning calorimetry （DSC） and scanning electron microscope （SEM）, the composite consists of the primary dendrite α-Ee （without Si） as well as the amorphous matrix. After being anneal at 800 K, the uniform spheroid particles are formed in the c/a composite, which does not form in the amorphous ribbon under the various annealing process. Energy dispersive analysis of X-rays （EDAX）, SEM and XRD were applied to give more detailed information. The formation and evolution of the particle may stimulate the possible application of the Fe-matrix amorphous alloy.

Pressure-volume-temperature and excess molar volume prediction of amorphous and crystallizable polymer blends by equation of state

In this work the statistical mechanical equation of state was developed for volumetric properties of crystalline and amorphous polymer blends.The Ihm-Song-Mason equations of state(ISMEOS) based on temperature and density at melting point(T_m and ρ_m) as scaling constants were developed for crystalline polymers such as poly(propylene glycol) + poly(ethylene glycol)-200(PPG + PEG-200),poly(ethylene glycol) methyl ether-300(PEGME-350) + PEG-200 and PEGME-350 + PEG-600.Furthermore,for amorphous polymer blends containing poly(2,6-dimethyl-1,4-phenylene oxide)(PPO) + polystyrene(PS) and PS + poly(vinylmethylether)(PVME),the density and surface tension at glass transition(ρ_g and γ_g) were used for estimation of second Virial coefficient.The calculation of second Virial coefficients(B_2),effective van der Waals co-volume(b) and correction factor(α) was required for judgment about applicability of this model.The obtained results by ISMEOS for crystalline and amorphous polymer blends were in good agreement with the experimental data with absolute average deviations of 0.84%and 1.04%,respectively.

Low Temperature Synthesis of Amorphous La0.7Zn0.3MnO3 Films Grown on p＋-Si Substrates and Its Resistive Switching Properties

Amorphous La0.7Zn0.3MnO3（LZMO） films were deposited on p＋-Si substrates by sol-gel method at low temperature of 450 ℃.The Ag/LZMO/p＋-Si device exhibits invertible bipolar resistive switching and the RHRS/RLRS was about 104-106 at room temperature which can be kept over 103 switching cycles.Better endurance characteristics were observed in the Ag/LZMO/p＋-Si device,the VSet and the VReset almost remained after 103 endurance switching cycles.According to electrical analyses,the conductor mechanism was in low resistor state（LRS） governed by the filament conductor and in the high state（HRS） dominated by the trapscontrolled space-charge-limited current（SCLC） conductor.

Construction of amorphous/crystalline heterointerfaces for enhanced electrochemical processes

Amorphous nanomaterials have emerged as potential candidates for energy storage and conversion owing to their amazing physicochemical properties.Recent studies have proved that the manipulation of amorphous nanomaterials can further enhance electrochemical performance.To date,various feasible strategies have been proposed,of which amorphous/crystalline(a-c)heterointerface engineering is deemed an effective approach to break through the inherent activity limitations of electrode materials.The following review discusses recent research progress on a-c heterointerfaces for enhanced electrochemical processes.The general strategies for synthesizing ac heterojunctions are first summarized.Subsequently,we highlight various advanced applications of a-c heterointerfaces in the field of electrochemistry,including for supercapacitors,batteries,and electrocatalysts.We also elucidate the synergistic mechanism of the crystalline phase and amorphous phase for electrochemical processes.Lastly,we summarize the challenges,present our personal opinions,and offer a critical perspective on the further development of a-c nanomaterials.

Enhanced high-temperature performance of Li-rich layered oxide via surface heterophase coating

Li-rich layered oxides have become one of the most concerned cathode materials for high-energy lithiumion batteries, but they still suffer from poor cycling stability and detrimental voltage decay, especially at elevated temperature. Herein, we proposed a surface heterophase coating engineering based on amorphous/crystalline Li3 PO4 to address these issues for Li-rich layered oxides via a facile wet chemical method. The heterophase coating layer combines the advantages of physical barrier effect achieved by amorphous Li3 PO4 with facilitated Li+diffusion stemmed from crystalline Li3 PO4. Consequently, the modified Li(1.2) Ni(0.2) Mn(0.6) O2 delivers higher initial coulombic efficiency of 92% with enhanced cycling stability at 55 °C(192.9 mAh/g after 100 cycles at 1 C). More importantly, the intrinsic voltage decay has been inhibited as well, i.e. the average potential drop per cycle decreases from 5.96 mV to 2.99 mV. This surface heterophase coating engineering provides an effective strategy to enhance the high-temperature electrochemical performances of Li-rich layered oxides and guides the direction of surface modification strategies for cathode materials in the future.

Microstructure evolution and deformation mechanism of amorphous/crystalline high-entropy-alloy composites

High-entropy amorphous alloys present high hardness,but low tensile ductility.Here,deformation behavior of the amorphous/crystalline Fe Co Cr Ni high-entropy alloy(HEA)composite prepared by the previous experiment is investigated using atomic simulations.The result shows the partial dislocations in the crystal HEA layer,and the formation of shear bands in the amorphous HEA layer occurs after yielding.The strength of the amorphous/crystalline HEA composite reduces with increasing the thickness of the amorphous layer,agreeing with the previous experiments.The coupled interaction between the crystal plasticity and amorphous plasticity in amorphous/crystalline HEA composites results in a more homogeneous redistribution of plastic deformation to cause interface hardening,due to the complex stress field in the amorphous layer.The current findings provide the insight into the deformation behavior of the amorphous/crystalline HEA composite at the nanoscale,which are useful for optimizing the structure of the HEA composite with high strength and good plasticity.

Mechanical properties of Fe-based amorphous–crystalline composite: a molecular dynamics simulation and experimental study

A new Fe-based amorphous–crystalline composite without non-metallic elements, Fe_(55)Cr_(15)Mo_(15)Ni_(10)W_(5), was prepared by melt-spinning. The formation ability and structure information were investigated by X-ray diffractometer(XRD), energy-dispersive spectrometer(EDS) and scanning electron microscope(SEM). The mechanical properties of the amorphous–crystalline composite were investigated by nanoindentation. A molecular dynamics simulation study was performed to simulate the formation of Fe_(55)Cr_(15)Mo_(15)Ni_(10)W_(5) amorphous alloy. The mechanical properties were obtained by compression simulations simultaneously. The results indicate that the Fe_(55)Cr_(15)Mo_(15)Ni_(10)W_(5) ribbon is an amorphous–crystalline composite structure with good ductility, and the hardness of the amorphous–crystalline composite is about 75%higher than that of master ingot. The simulation mechanical properties are in good agreement with the results of nanoindentation at the nanoscale.

Wet-chemical synthesis and applications of amorphous metalcontaining nanomaterials

In the past decades,metal-containing nanomaterials have attracted increasing interests owing to their intriguing physicochemical properties and various promising applications.Recent research has revealed that the phase of metal-containing nanomaterials could significantly affect their properties and functions.In particular,nanomaterials with amorphous phase,which possess long-range disordered atomic arrangements,and the amorphous/crystalline heterophase nanostructures comprised of both amorphous and crystalline phases,have exhibited superior performance in various applications,e.g.,catalysis and energy storage.In this review,a brief overview of the recent progress on the wet-chemical synthesis and applications of amorphous and amorphous/crystalline heterophase metal-containing nanomaterials has been provided.Subsequently,on the basis of different categories of metal-containing nanomaterials,including metals,metal alloys,and metal compounds,their synthetic routes and promising applications will be highlighted.Finally,current challenges and some personal perspectives in this emerging research field will be proposed.

DENSITY, EQUILIBRIUM HEAT OF FUSION AND EQUILIBRIUM MELTING TEMPERATURE OF NYLON 1010

The density, equilibrium heat of fusion and equilibrium melting temperature of Nylon 1010 were determined by means of infrared spectrum, differential scanning calorimetry, wide angle X-ray diffraction and density measurement techniques. According to Starkweatber' s method crystalline density ρ_c and amorphous density ρ_a were estimated to be 1.098 and 1.003 g/cm^3 respectively by extrapolating the straight lines of the IR absorbanee against density to zero intensity. Owing to the less intense in absorbance and less sensitive to the change in crystallinity of the amorphors band the thus obtained ρ_c was too low in value. Thereby the value of the ratio ρ_c /ρ_a is far less than generally accepted mean value for most crystalline polymers. Accordingly, traditional X-ray diffraction method was used through determining thc crystalline dimension(a=4.9, b=5.4, c=27.8, α=49° β=77.0°, γ=63.5°), and a rather correct value of ρ_c or the crystal density 1.13 g/cm^3 was obtained. The equilibrium heat of fusion △H_m^0 was estimated to be 244.0 J/g piotting △H_m 's of specimens with different crystallinity against their corre sponding specific volumes_(sp), and extrapolating to completely crystalline condition (_(sp)~c= 1/ρ_c) As to the equilibrium melting temperature T_m^0, because of the easiness of recrystallization of melt crystallized Nylon 1010 specimen, the well-known Hoffman's T_m-T_c method failed in determining this value and an usually rarely used Kamide double extrapolation method was adopted. The so obtained value of T_m^0 487 seems to be fairly reasonable.

Control of epitaxial growth at a-Si:H/c-Si heterointerface by the working pressure in PECVD

The epitaxial-Si（epi-Si） growth on the crystalline Si（c-Si） wafer could be tailored by the working pressure in plasmaenhanced chemical vapor deposition（PECVD）.It has been systematically confirmed that the epitaxial growth at the hydrogenated amorphous silicon（a-Si：H）/c-Si interface is suppressed at high pressure（hp） and occurs at low pressure（1p）.The hp a-Si：H,as a purely amorphous layer,is incorporated in the 1p-epi-Si/c-Si interface.We find that：（i） the epitaxial growth can also occur at a-Si：H coated c-Si wafer as long as this amorphous layer is thin enough;（ii） with the increase of the inserted hp layer thickness,lp epi-Si at the interface is suppressed,and the fraction of a-Si：H in the thin films increases and that of c-Si decreases,corresponding to the increasing minority carrier lifetime of the sample.Not only the epitaxial results,but also the quality of the thin films at hp also surpasses that at lp,leading to the longer minority carrier lifetime of the hp sample than the lp one although they have the same amorphous phase.

Unlocking supercapacitive energy storage potential:Catalyzing electrochemically inactive manganese oxides to active MnO_(2)via heterostructure reconstruction

Advancing supercapacitor system performance hinges on the innovation of novel electrode materials seamlessly integrated within distinct architectures.Herein,we introduce a direct approach for crafting nanorod arrays featuring crystalline/amorphous CuO/MnO_(2)−x.This reconfigured heterostructure results in an elevated content of electrochemically active MnO_(2).The nanorod arrays serve as efficient capacitive anodes and are easily prepared via low-potential electrochemical activation.The resulting structure spontaneously forms a p–n heterojunction,developing a built-in electric field that dramatically facilitates the charge transport process.The intrinsic electric field,in conjunction with the crystalline/amorphous architecture,enables a large capacitance of 1.0 F·cm^(−2)at 1.0 mA·cm^(−2),an ultrahigh rate capability of approximately 85.4%at 15 mA·cm^(−2),and stable cycling performance with 92.4%retention after 10,000 cycles.Theoretical calculations reveal that the presence of heterojunctions allows for the optimization of the electronic structure of this composite,leading to improved conductivity and optimized OH−adsorption energy.This work provides new insights into the rational design of heterogeneous nanostructures,which hold great potential in energy storage applications.

Advances in Investigation of Fe-based Glass-forming Alloy Melts

Continuous precision casting is an important trend in modern industrialization.Clustering effects in glassforming metallic liquids tremendously influence the properties of rapidly quenched ribbons;therefore,much attention has been paid to the study of Fe-based glass-forming melts at high temperatures.Recent investigations of these melts are categorized and reviewed.It is concluded that more efforts are still required to reveal the discipline of amorphization brought about by rapid quenching of Fe-based glass-forming melts.