Industrial wastes such as steel slag and coal gangue etc.were chosen as raw materials for preparing ceramic via the conventional solid-state reaction method.With steel slag and coal gangue mixed in various mass ratios...Industrial wastes such as steel slag and coal gangue etc.were chosen as raw materials for preparing ceramic via the conventional solid-state reaction method.With steel slag and coal gangue mixed in various mass ratios,from 100%steel slag to 100%coal gangue at 10%intervals,microstructure and possible phase evolution of the coal gangue-steel slag ceramics were investigated using X-ray powder diffraction,scanning electron microscopy,mercury intrusion porosimetry and Archimedes boiling method.The experimental results suggest that the phase compositions of the as-prepared ceramics could be altered with the increased amount of coal gangue in the ceramics.The anorthite-diopside eutectic can be formed in the ceramics with the mass ratios of steel slag to coal gangue arranged from 8:2 to 2:8,which was responsible for the melting of the steel slag-coal gangue ceramics at relatively high temperature.Further investigations on the microstructure suggested that the addition of the proper amount of steel slag in ceramic compositions was conducive to the pore formation and further contributed to an increment in porosity.展开更多
The microstructure evolution law and the structure of precipitates produced during the tempering of steel AerMet100 based on TEM observation and the calibration of diffraction spot were revealed.The electronic structu...The microstructure evolution law and the structure of precipitates produced during the tempering of steel AerMet100 based on TEM observation and the calibration of diffraction spot were revealed.The electronic structure and the stability of the MoxCr2-xC phase were calculated using the plane-wave pseudo-potential method on basis of density functional theory.TEM observations show that the precipitation phases Fe3C and Fe2-xCx(x=0.05~0.14) between martensite lath are produced at 425 and 480 ℃,respectively.The increase of tempering temperature or time can lead to the redissolution of both phases Fe3C and Fe2-xCx,and also lead to the precipitation of the phase Cr2C in martensite lath.The calculation results of formation energies and the density of state(DOS) demonstrate that in point of MoxCr2-xC structures formed during tempering,the early precipitation phase is Cr2C and finally later evolves into Mo2C phase with diffusing of incorporation of Mo atom into the Cr2C crystal cell,lattice,which can results in a energy decreases of the structure MoxCr2-xC phase with the increase of x.展开更多
Phase evolution and magnetic properties of (Nd_o.95La_0.05)9.5-11Febal.M_2B10.5. where M=Cr, Ti, Nb, V, Mo, Zr, Hf, Ta, Mn or W, melt spun ribbons have been investigated. Almost all the alloy ribbons. except for(Nd_0....Phase evolution and magnetic properties of (Nd_o.95La_0.05)9.5-11Febal.M_2B10.5. where M=Cr, Ti, Nb, V, Mo, Zr, Hf, Ta, Mn or W, melt spun ribbons have been investigated. Almost all the alloy ribbons. except for(Nd_0.95La_0.05)_9.5Fe_78M_2B_10.5(M=Mo and Mn),consist merely two magnetic phases, namely α-Fe and R_2Fe_14B, which display a better combination of _iH_c and magnetic energy product. Remanence (Br) and coercivity (i_H_c) values in the range of 8.0 to 9.1 kG and 9.5 to 18.9 kOe. respectively, can be achieved. Among compositions studied, the Ti and W-substitutions were found to be most effective in increasing the Br and i_H_c, respectively. For a fixed refractory metal substitution, namely, M=C_r, Ti or Nb, an increase in the total rare earth concentration resulted in nanocomposites of small grain sizes and a high volume fraction of the R_2Fe_14B phase, leading to an increase in the magnetic properties.展开更多
Powder in tube process(PIT) was adopted for the fabrication of single filament Bi-2223 tapes, and a heat treatment process including the first heat treatment(HT1), intermediate rolling(IR), and second heat treat...Powder in tube process(PIT) was adopted for the fabrication of single filament Bi-2223 tapes, and a heat treatment process including the first heat treatment(HT1), intermediate rolling(IR), and second heat treatment(HT2) was performed. The phase evolution mechanism and microstructure changes during these heat treatment processes were systematically discussed. The influences of HT1 parameters on the phase evolution process of Bi-2223 tapes were discussed. With the optimized HT1 process, a proper Bi-2223 content of about 90% was achieved. HT2 process was also optimized by adding a post annealing process. An obvious increase of current capacity was obtained due to the enhancement of intergrain connections. Single filament Bi-2223 tapes with the critical current of Ic-90 A were fabricated with the optimized sintering process.展开更多
The understanding of phase competing is of pretty importance in designing high glass-forming systems. In this work, it has been investigated experimentally and theoretically the phase evolution and glass formation of ...The understanding of phase competing is of pretty importance in designing high glass-forming systems. In this work, it has been investigated experimentally and theoretically the phase evolution and glass formation of a wedge-casting Fe-based alloy. The results indicated that the phase formation was sensitive to the wedge position, i.e., there were amorphous phase, Fe_(2)P, {Fe, Ni} and α-Fe precipitates as well as M_(23)B_(6) phase at the distances of 3, 10 and 20 mm away from the wedge-tip, respectively. These were closely connected with the variation of cooling rate, embodied in the heat transfer at the solidification process. Furthermore, we constructed the time–temperature-transformation (TTT) diagrams of the iron-based alloy and these crystal phases through calculating Rc-related functions. Finally, the glass-forming features of the wedge-shaped Fe-based alloy have been elucidated in accordance with a crystallization kinetics analysis of the recorded temperature data and the phase selection competition. This research provides us an insight into in-depth understanding bulk metallic glass from the perspective of kinetics competition of crystallization phases.展开更多
PbMo6S 8 superconducting materials are considered to have great potential for practical applications at low temperatures and high fields due to their high upper critical field,low anisotropy,and low preparation cost.I...PbMo6S 8 superconducting materials are considered to have great potential for practical applications at low temperatures and high fields due to their high upper critical field,low anisotropy,and low preparation cost.In this work,PbMo_(6)S_(8) bulks were prepared through a solid‐state sintering process using PbS,Mo,and MoS_(2) as raw materials.The phase evolution mechanism during the sintering of PbMo_(6)S_(8) was studied in detail.It was found that during sintering at 750℃ for 24 h,both the S and Pb atoms diffuse into the Mo and MoS_(2) particles,leading to the formation of the PbMo_(6)S_(8) phase.After sintering at 950℃ for 72 h,a high superconducting phase content was obtained in the bulk;however,numerous pores remained.Therefore,in order to obtain a higher density for the bulk,a two‐step sintering process was developed.Based on this technique,PbMo_(6)S_(8) bulks with a higher bulk density and a higher superconducting phase content were obtained.This study provides an effective method for the fabrication of high‐quality precursor powders,which can be the foundation for the future fabrication of PbMo_(6)S_(8) superconducting long wires or tapes for practical applications.展开更多
In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical prope...In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical properties and sintering pot tests were used to study the sintering behavior.In addition,a grey correlation mathematical model was used to calculate and compare the comprehensive sintering performance under different calcium-rich iron ore contents.The results demonstrate that the Ca-rich iron ore has coarse grain size and strong self-fusing characteristics with Ca element in the form of calcite(CaCO_(3)) and the liquid phase produced by the self-fusing of the calcium-rich iron ore is well crystallized.Its application with a 20wt%content in sintering improves sinter productivity,reduces fuel consumption,enhances reduction index,and improves gas permeability in blast furnace by 0.45 t/(m^(2)·h),6.11 kg/t,6.17%,and 65.39 kPa·℃,respectively.The Ca-rich iron ore sintering can improve the calorific value of sintering flue gas compared with magnetite sintering,which is conducive to recovering heat for secondary use.As the content of the Ca-rich iron ore increases,sinter agglomeration shifts from localized liquid-phase bonding to a combination of localized liquid-phase bonding and iron oxide crystal connection.Based on an examination of the greater weight value of productivity with grey correlation analysis,the Ca-rich iron ore is beneficial for the comprehensive index of sintering in the range of 0-20wt%content.Therefore,it may be used in sintering with magnetite concentrates as the major ore species.展开更多
The Sinian-Lower Paleozoic (also called the lower association) in Sichuan (四川) basin has undergone geologic evolution for several hundred million years. The subsidence history of the Sinian-Lower Paleozoic can b...The Sinian-Lower Paleozoic (also called the lower association) in Sichuan (四川) basin has undergone geologic evolution for several hundred million years. The subsidence history of the Sinian-Lower Paleozoic can be divided into four stages: the stable subsidence during Cambrian and Silurian; the uplift and denudation during Devonian and Carboniferous; the subsidence (main process) during Permian to Late Cretaceous; and the rapid uplift and denudation since Late Cretaceous. The later two stages could be regarded as critical factors for the development of oil and gas in the lower association. The evolution of energy field such as temperature, pressure, and hydrocarbon phase in the lower association during the deep burial and uplift in the third stage might be induced as follows: (1) super-high pressure was developed during oil-cracking, previous super-high pressure was sustained, or changed as normal pressure during late uplift; (2) temperature increased with deep burial during persistent subsidence and decreased during uplift in late stage; (3) as a response to the change of the energy field, hydrocarbon phase experienced a series of changes such as organic material (solid), oil (liquid), oil-cracking gas (gaseous) + bitumen (solid) + abnormal high pressure, gas cap gas with super-high pressure (gaseous) + bitumen (solid) + water soluble gas (liquid), and gas in pool (gaseous) + water soluble gas (liquid) + bitumen (solid). The restoration of hydrocarbon phase evolution is of important value for the exploration of natural gas in the Sinian-Lower Paleozoic in Sichuan basin.展开更多
In the present work,the nature of phase evolution of(1x)(Na_(0.5)Bi_(0.5))TiO_(3)-xSrTiO_(3)(NBT-xST)solid solutions with x of 0e0.6 is revealed by characterizing the dielectric and ferroelectric properties.Two unique...In the present work,the nature of phase evolution of(1x)(Na_(0.5)Bi_(0.5))TiO_(3)-xSrTiO_(3)(NBT-xST)solid solutions with x of 0e0.6 is revealed by characterizing the dielectric and ferroelectric properties.Two unique dielectric anomalies associated with high-temperature nanoregions(PNRs)in the ergodic relaxor(ER)state and low-temperature PNRs in the nonergodic relaxor(NR)state are identified.Characteristic temperatures,including TB,TRT*,Tm,Td and TT*,are determined in fresh and poled states on the basis of the characteristics of the evolution of these two dielectric anomalies.The whole evolution of the transition from the NR state to the ER state is reflected by the temperature-dependent polarization versus electric field(P-E)hysteresis loops,i.e.,from the square loops,via the double-like loops,to the slim loops.The characteristic temperatures,including TP-N,TN-R and TR-dis,are determined by the characteristics of the evolution of P-E loops.Accordingly,a phase diagram of NBT-xST was constructed according to these characteristic temperatures.Most importantly,the relationship between polarization responses and heterogeneous polar phase coexistence has been established and a schematic diagram is given.This work will help to understand the phase evolution and its impact on the macroscopic properties of NBT and the associated NBT-based solid solutions.展开更多
Owing to the complex composition architecture of these solid solutions,some fundamental issues of the classical(1-x)(Bi_(1/2)Na_(1/2))TiO_(3) -x(Bi_(1/2)K_(1/2))TiO_(3)(BNT-xBKT)binary system,such as details of phase ...Owing to the complex composition architecture of these solid solutions,some fundamental issues of the classical(1-x)(Bi_(1/2)Na_(1/2))TiO_(3) -x(Bi_(1/2)K_(1/2))TiO_(3)(BNT-xBKT)binary system,such as details of phase evolution and optimal Na/K ratio associated with the highest strain responses,remain unresolved.In this work,we systematically investigated the phase evolution of the BNT-xBKT binary solid solution with x ranging from 0.12 to 0.24 using not only routine X-ray diffraction and weak-signal dielectric characterization,but also temperature-dependent polarization versus electric field(P-E)and current versus electric field(I-E)curves.Our results indicate an optimal Na/K ratio of 81/19 based on high-field polarization and elec-trostrain characterizations.As the temperature increased above 100?C,the x¼0.19 composition pro-duces ultrahigh electrostrains(>0.5%)with high thermal stability.The ultrahigh and stable electrostrains were primarily due to the combined effect of electric-field-induced relaxor-to-ferroelectric phase tran-sition and ferroelectric-to-relaxor diffuse phase transition during heating.More specifically,we revealed the relationship between phase evolution and electrostrain responses based on the characteristic tem-peratures determined by both weak-field dielectric and high-field ferroelectric/electromechanical property characterizations.This work not only clarifies the phase evolution in BNT-xBKT binary solid solution,but also paves the way for future strain enhancement through doping strategies.展开更多
Using a hydrothermal method, by adjusting the reactant ratios, the hydrothermal temperatures, the hydrothermal time, and the pH values of prepared solutions, 1 mol.% Eu3+ doped K-Lu-F system optical materials were sy...Using a hydrothermal method, by adjusting the reactant ratios, the hydrothermal temperatures, the hydrothermal time, and the pH values of prepared solutions, 1 mol.% Eu3+ doped K-Lu-F system optical materials were synthesized under control. For com- parison, the sample was also synthesized by a co-precipitation method. The X-ray diffraction (XRD) results suggested that the final crystalline phases had great relations with the hydrothermal synthesis conditions. The field emission scanning electron microscopy (FE-SEM) images and the energy-dispersive spectroscopy (EDS) patterns indicated that the morphologies and the components of some representative samples also varied with the synthesis conditions. Eu3+, acting as a probe, exhibited different optical proper- ties in the K-Lu-F system optical materials, which also indirectly proved the phase evolution of the final products. The results sug- gested that there were many crystalline phases with different symmetry in the K-Lu-F system. They would be good host matrices for the emitters.展开更多
Natural gas-hydrates are valuable energy resource with rich deposits,and their thermal transport and thermal dynamic mechanical behaviors significantly affect the long-term production process and phase change-based th...Natural gas-hydrates are valuable energy resource with rich deposits,and their thermal transport and thermal dynamic mechanical behaviors significantly affect the long-term production process and phase change-based thermal energy storage characteristics of these energy resources.This paper aims to propose novel relations to predict the thermophysical properties,to investigate the hydrate phase evolution in microstructures,and to study the thermal transport and thermal dynamic mechanical properties.Hydrates formation experiments in sandpack samples and ultrasonic wave tests are conducted with the aid of X-ray CT imaging.Digitalization microstructures models and variables are defined to describe the hydrate phase evolution,and novel relations are proposed to accurately predict the thermophysical properties based on the microporosity and ultrasonic wave velocities.The thermal transport and thermal dynamic mechanical properties in microstructures with hydrate,water,residuary pore and grain phases are studied.Results show that the average errors of porosity,P-wave and S-wave velocities between the experimental data and computed results by the proposed relations are less than 5%,indicating the accuracy and reliability of the proposed method.The temperature fraction decreases with increasing underground temperature and decreasing hydrate saturation.The thermal stress and thermal displacement increase as temperature and hydrate saturation increase.There are strong anisotropy for the temperature fraction,thermal stress and thermal displacement during the thermal transport of hydrates.展开更多
Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anod...Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anode of the Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies(Ov-BMO-Cu)are in-situ generated by phase separation and hydrogen etching using nanoporous Cu-Mn alloy as selfsacrificial templates.On this basis,we have elucidated the relationship between the phase evolution,oxygen vacancies and sodium-ion storage mechanisms,further demonstrating the evolution of oxygen vacancies and the inhibition effect of manganese oxides as an“anchor”on grain aggregation of copper oxides.The kinetic analyses confirm that the expanded lattice space and increased oxygen vacancies of cycled Ov-BMO-Cu synergistically guarantee effective sodium-ion diffusion and storage mechanisms.Therefore,the Ov-BMO-Cu electrode exhibits higher reversible capacities of 4.04 mA h cm^(-2)at 0.2 mA cm^(-2)after 100 cycles and 2.20 m A h cm^(-2)at 1.0 mA cm^(-2)after 500 cycles.Besides,the presodiated Ov-BMO-Cu anode delivers a considerable reversible capacity of 0.79 m A h cm^(-2)at 1.0 mA cm^(-2)after 60 cycles in full cells with Na_(3)V_(2)(PO_(4))_(3)cathode,confirming its outstanding practicality.Thus,this work is expected to provide enlightenment for designing high-capacity bimetallic oxide anodes.展开更多
Thermodynamic analysis of refractory siderite ore during carbothermic reduction was conducted. Micro- structure characteristics and phase transformation of siderite ore during sodium-carbonate-added catalyzing carboth...Thermodynamic analysis of refractory siderite ore during carbothermic reduction was conducted. Micro- structure characteristics and phase transformation of siderite ore during sodium-carbonate-added catalyzing carboth- ermic reduction were investigated. X-ray diffraction (XRD), scanning electron microscopy and energy-dispersive analysis of X rays were used to characterize the reduced samples. Results indicate that the solid reaction between FeO and SiO2 is inevitable during carbothermic reduction and the formation of fayalite is the main hindrance to the rapid reduction of siderite. The phase transformation of present siderite ore can be described as: siderite-magnetite-metallic iron, complying with the formation of abundant fayalite. Improving the reduction temperature (-1050 -C ) and duration is helpful for the formation and aggregation of metallic iron. The iron particle size in the reduced ore was below 20 l-m, and fayalite was abundant in the absence of sodium carbonate. With 5% Na2CO3 addition, the iron particle size in the reduced ore was generally above 50μm, and the diffraction intensity associated with metallic iron in the XRD pattern increased. The Na2O formed from the dissociation of Na2 CO3 can catalyze the carbothermie reduction of the siderite. This catalytic activity may be mainly caused by an increase in the reducing reaction activity of FeO.展开更多
Binary immiscible Al-Sn alloy is a very important potential anode material for lithium ion batteries.The phase stability and separation process of Al-Sn film,fabricated by magnetron co-sputtering method,was investigat...Binary immiscible Al-Sn alloy is a very important potential anode material for lithium ion batteries.The phase stability and separation process of Al-Sn film,fabricated by magnetron co-sputtering method,was investigated by X-ray diffractometer(XRD),differential scanning calorimetry(DSC) and in situ transmission electron microscopy(TEM) and explained by Miedema theoretical model.Thermodynamic analysis reveals that the asdeposited Al-Sn film will decompose spontaneously into Al-riched areas and Sn-riched areas because of the positive mixing enthalpy.The crystallization process takes place when the Al content in the Al-riched area or Sn content in the Sn-riched area increases.Experimental results show that Al-Sn thin film is composed of an amorphous matrix and well-dispersed composite nanoparticles.Every particle contains an Al-riched area and a Sn-riched area.The Snriched area crystallizes and swallows up the Al-riched area gradually during heating through uphill diffusion of the Sn atoms.Based on the theoretical analysis and experimental results,an empirical model to explain the phase evolution process in the Al-Sn film was proposed.展开更多
Li-rich Li[Li0.2Mn0.54Ni0.13Co0.13]02(LMNC) powders were synthesized by a gel-combustion method. The related microstructure, electrochemical performance and electrochemically induced phase evolution were characteriz...Li-rich Li[Li0.2Mn0.54Ni0.13Co0.13]02(LMNC) powders were synthesized by a gel-combustion method. The related microstructure, electrochemical performance and electrochemically induced phase evolution were characterized. The 900℃ calcined powders have a hexagonal layered structure with high ordered degree and low cationic mixing level. The calcined materials as cathode electrode for Li-ion battery deliver the high electrochemical properties with an initial discharge capacity of 243.5 mA. h. g-1 at 25 mA.g-1 and 249.2 mA-h.g-1 even after 50 cycles. The electrochemically induced phase evolution investigated by a transmission electron microscopy indicates that Li+ ions deintercalated first from the LiMO2 (M = Mn, Co, Ni) component and then from Li2MnO3 component in the LMNC during the charge process, while Li+ ions intercalated into Li1-xMO2 component followed by into MnO2 component during the discharge process.展开更多
This paper systematically reports the thermodynamic characteristic and phase evolution of immiscible Cr–Mo binary alloy during mechanical alloying(MA) process. The Cr–35Mo(in at%) powder mixture was milled at 24...This paper systematically reports the thermodynamic characteristic and phase evolution of immiscible Cr–Mo binary alloy during mechanical alloying(MA) process. The Cr–35Mo(in at%) powder mixture was milled at 243 and258 K, respectively, for different time. For comparative study, Cr–15Mo and Cr–62Mo powder mixtures were milled at 243 K for 18 h. Solid solution Cr(Mo) with body-centered cubic(bcc) crystal structure and amorphous Cr(Mo) alloy was obtained during MA process caused by high-energy ball milling. Based on the Miedema's model, the free-energy change for forming either a solid solution or an amorphous in Cr–Mo alloy system is positive but small at a temperature range between 200 and 300 K. The thermodynamical barrier for forming alloy in Cr–Mo system can be overcome when MA occurs at 243 K, and the supersaturated solid solution crystal nuclei with bcc structure form continually, and three supersaturated solid solutions of Cr–62Mo, Cr–35Mo and Cr–15Mo formed. Milling the Cr–35Mo powder mixture at 258 K, the solid solution Cr(Mo) forms firstly, and then the solid solution Cr(Mo) transforms into the amorphous Cr(Mo)alloy with a few of nanocrystallines when milling is prolonged. At higher milling temperature, it is favorable for the formation of the amorphous phase, as indicated by the thermodynamical calculation for immiscible Cr–Mo alloy system.展开更多
Studies of lithology, sedimentary facies and the distribution regularity of SiO2 and Al2O3 contents and Al2O3/SiO2 ratio allow us to divide the Upper Pleistocene-Holocene Series represented by the MUanggouwan section ...Studies of lithology, sedimentary facies and the distribution regularity of SiO2 and Al2O3 contents and Al2O3/SiO2 ratio allow us to divide the Upper Pleistocene-Holocene Series represented by the MUanggouwan section in China's Salawnsu River valley into six segments: MGS1, MGS2, MGS3, MGS4, MGS5 and MGS6. The boundary ages for MGS1 (the Dishaogouwan and Dagouwan Formations), MGS2 (the upper Chengchuan Formation), MGS3 (the middle Chengchuan Formation), MGS4 (the lower Chengchuan Formation), MGS5 (most strata of the Salawusu Formation) and MGS6 (the bottom of the Salawusu Formation and the top of the Lishi Formation) correspond to those of MIS1, MIS2, MIS3, MIS4, MISS and MIS6, respectively, from deep sea sediments or continental glaciers. MGS5 can be subdivided into five subsegments (MGS5a, MGS5b, MGS5c, MGS5d and MGS5e) and the boundary ages of these subsegments correspond to those of MISSa, MISSb, MIS5c, MIS5d and MIS5e, respectively. Based on the paleoenvironment and paleoecology indicated by the primary chemical elements, fossil vertebrates, mollusks and pollen grains, we hypothesize that MGS1, MGS2, MGS3, MGS4, MGS5 and MGS6 and the subsegments of MGS5 match the corresponding stages for oxygen isotopes in the deep sea sediments and continental glaciers, and the substages of MIS5 in terms of climatic characters, further explaining the phenomena that determined the formation of the late Quaternary strata and the paleontology of the Salawusu River valley. These phenomena relate to fluctuations in the global climate (and particularly in the East Asian monsoon) during the glacial and interglacial periods.展开更多
We elucidate the importance of a capping layer on the structural evolution and phase change properties of carbondoped Ge2 Sb2 Te5(C-GST) films during heating in air. Both the C-GST films without and with a thin SiO2...We elucidate the importance of a capping layer on the structural evolution and phase change properties of carbondoped Ge2 Sb2 Te5(C-GST) films during heating in air. Both the C-GST films without and with a thin SiO2 capping layer(C-GST and C-GST/SiO2) are deposited for comparison. Large differences are observed between C-GST and C-GST/SiO2 films in resistance-temperature, x-ray diffraction, x-ray photoelectron spectroscopy,Raman spectra, data retention capability and optical band gap measurements. In the C-GST film, resistancetemperature measurement reveals an unusual smooth decrease in resistance above 110℃ during heating. Xray diffraction result has excluded the possibility of phase change in the C-GST film below 170℃. The x-ray photoelectron spectroscopy experimental result reveals the evolution of Te chemical valence because of the carbon oxidation during heating. Raman spectra further demonstrate that phase changes from an amorphous state to the hexagonal state occur directly during heating in the C-GST film. The quite smooth decrease in resistance is believed to be related with the formation of Te-rich GeTe4-n Gen(n = 0, 1) units above 110℃ in the C-GST film. The oxidation of carbon is harmful to the C-GST phase change properties.展开更多
A series of material parameters are derived from atomistic simulations and implemented into a phase field(PF) model to simulate void evolution in body-centered cubic(bcc) iron subjected to different irradiation do...A series of material parameters are derived from atomistic simulations and implemented into a phase field(PF) model to simulate void evolution in body-centered cubic(bcc) iron subjected to different irradiation doses at different temperatures.The simulation results show good agreement with experimental observations — the porosity as a function of temperature varies in a bell-shaped manner and the void density monotonically decreases with increasing temperatures; both porosity and void density increase with increasing irradiation dose at the same temperature. Analysis reveals that the evolution of void number and size is determined by the interplay among the production, diffusion and recombination of vacancy and interstitial.展开更多
基金Funded by the Scientific and Technological Innovation Project of Carbon Emission Peak and Carbon Neutrality of Jiangsu Province(No.BE2022028-4)。
文摘Industrial wastes such as steel slag and coal gangue etc.were chosen as raw materials for preparing ceramic via the conventional solid-state reaction method.With steel slag and coal gangue mixed in various mass ratios,from 100%steel slag to 100%coal gangue at 10%intervals,microstructure and possible phase evolution of the coal gangue-steel slag ceramics were investigated using X-ray powder diffraction,scanning electron microscopy,mercury intrusion porosimetry and Archimedes boiling method.The experimental results suggest that the phase compositions of the as-prepared ceramics could be altered with the increased amount of coal gangue in the ceramics.The anorthite-diopside eutectic can be formed in the ceramics with the mass ratios of steel slag to coal gangue arranged from 8:2 to 2:8,which was responsible for the melting of the steel slag-coal gangue ceramics at relatively high temperature.Further investigations on the microstructure suggested that the addition of the proper amount of steel slag in ceramic compositions was conducive to the pore formation and further contributed to an increment in porosity.
文摘The microstructure evolution law and the structure of precipitates produced during the tempering of steel AerMet100 based on TEM observation and the calibration of diffraction spot were revealed.The electronic structure and the stability of the MoxCr2-xC phase were calculated using the plane-wave pseudo-potential method on basis of density functional theory.TEM observations show that the precipitation phases Fe3C and Fe2-xCx(x=0.05~0.14) between martensite lath are produced at 425 and 480 ℃,respectively.The increase of tempering temperature or time can lead to the redissolution of both phases Fe3C and Fe2-xCx,and also lead to the precipitation of the phase Cr2C in martensite lath.The calculation results of formation energies and the density of state(DOS) demonstrate that in point of MoxCr2-xC structures formed during tempering,the early precipitation phase is Cr2C and finally later evolves into Mo2C phase with diffusing of incorporation of Mo atom into the Cr2C crystal cell,lattice,which can results in a energy decreases of the structure MoxCr2-xC phase with the increase of x.
基金National Science Council, Taiwan! under grant !No. NSC-87-2112-M194-005.
文摘Phase evolution and magnetic properties of (Nd_o.95La_0.05)9.5-11Febal.M_2B10.5. where M=Cr, Ti, Nb, V, Mo, Zr, Hf, Ta, Mn or W, melt spun ribbons have been investigated. Almost all the alloy ribbons. except for(Nd_0.95La_0.05)_9.5Fe_78M_2B_10.5(M=Mo and Mn),consist merely two magnetic phases, namely α-Fe and R_2Fe_14B, which display a better combination of _iH_c and magnetic energy product. Remanence (Br) and coercivity (i_H_c) values in the range of 8.0 to 9.1 kG and 9.5 to 18.9 kOe. respectively, can be achieved. Among compositions studied, the Ti and W-substitutions were found to be most effective in increasing the Br and i_H_c, respectively. For a fixed refractory metal substitution, namely, M=C_r, Ti or Nb, an increase in the total rare earth concentration resulted in nanocomposites of small grain sizes and a high volume fraction of the R_2Fe_14B phase, leading to an increase in the magnetic properties.
基金Funded by the National Natural Science Foundation of China(No.51472206)the National ITER Program of China(2015GB115001)the Program for Innovative Research Team in Shaanxi Province(No.2013KCT-07)
文摘Powder in tube process(PIT) was adopted for the fabrication of single filament Bi-2223 tapes, and a heat treatment process including the first heat treatment(HT1), intermediate rolling(IR), and second heat treatment(HT2) was performed. The phase evolution mechanism and microstructure changes during these heat treatment processes were systematically discussed. The influences of HT1 parameters on the phase evolution process of Bi-2223 tapes were discussed. With the optimized HT1 process, a proper Bi-2223 content of about 90% was achieved. HT2 process was also optimized by adding a post annealing process. An obvious increase of current capacity was obtained due to the enhancement of intergrain connections. Single filament Bi-2223 tapes with the critical current of Ic-90 A were fabricated with the optimized sintering process.
基金This work was supported by the National Natural Science Foundation of China(Nos.U1908219 and 52171163)the Key Research Program of the Chinese Academy of Sciences(No.ZDRW-CN-2021-2-2).The authors were also grateful to W.Y.Lu from IMR for helps from wedge sample preparation and fruitful discussions.
文摘The understanding of phase competing is of pretty importance in designing high glass-forming systems. In this work, it has been investigated experimentally and theoretically the phase evolution and glass formation of a wedge-casting Fe-based alloy. The results indicated that the phase formation was sensitive to the wedge position, i.e., there were amorphous phase, Fe_(2)P, {Fe, Ni} and α-Fe precipitates as well as M_(23)B_(6) phase at the distances of 3, 10 and 20 mm away from the wedge-tip, respectively. These were closely connected with the variation of cooling rate, embodied in the heat transfer at the solidification process. Furthermore, we constructed the time–temperature-transformation (TTT) diagrams of the iron-based alloy and these crystal phases through calculating Rc-related functions. Finally, the glass-forming features of the wedge-shaped Fe-based alloy have been elucidated in accordance with a crystallization kinetics analysis of the recorded temperature data and the phase selection competition. This research provides us an insight into in-depth understanding bulk metallic glass from the perspective of kinetics competition of crystallization phases.
基金supported Northwest Institute of Non‐ferrous Metal Research Funding(No.YK2117).
文摘PbMo6S 8 superconducting materials are considered to have great potential for practical applications at low temperatures and high fields due to their high upper critical field,low anisotropy,and low preparation cost.In this work,PbMo_(6)S_(8) bulks were prepared through a solid‐state sintering process using PbS,Mo,and MoS_(2) as raw materials.The phase evolution mechanism during the sintering of PbMo_(6)S_(8) was studied in detail.It was found that during sintering at 750℃ for 24 h,both the S and Pb atoms diffuse into the Mo and MoS_(2) particles,leading to the formation of the PbMo_(6)S_(8) phase.After sintering at 950℃ for 72 h,a high superconducting phase content was obtained in the bulk;however,numerous pores remained.Therefore,in order to obtain a higher density for the bulk,a two‐step sintering process was developed.Based on this technique,PbMo_(6)S_(8) bulks with a higher bulk density and a higher superconducting phase content were obtained.This study provides an effective method for the fabrication of high‐quality precursor powders,which can be the foundation for the future fabrication of PbMo_(6)S_(8) superconducting long wires or tapes for practical applications.
基金financially supported by the National Natural Science Foundation of China(No.52174291)。
文摘In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical properties and sintering pot tests were used to study the sintering behavior.In addition,a grey correlation mathematical model was used to calculate and compare the comprehensive sintering performance under different calcium-rich iron ore contents.The results demonstrate that the Ca-rich iron ore has coarse grain size and strong self-fusing characteristics with Ca element in the form of calcite(CaCO_(3)) and the liquid phase produced by the self-fusing of the calcium-rich iron ore is well crystallized.Its application with a 20wt%content in sintering improves sinter productivity,reduces fuel consumption,enhances reduction index,and improves gas permeability in blast furnace by 0.45 t/(m^(2)·h),6.11 kg/t,6.17%,and 65.39 kPa·℃,respectively.The Ca-rich iron ore sintering can improve the calorific value of sintering flue gas compared with magnetite sintering,which is conducive to recovering heat for secondary use.As the content of the Ca-rich iron ore increases,sinter agglomeration shifts from localized liquid-phase bonding to a combination of localized liquid-phase bonding and iron oxide crystal connection.Based on an examination of the greater weight value of productivity with grey correlation analysis,the Ca-rich iron ore is beneficial for the comprehensive index of sintering in the range of 0-20wt%content.Therefore,it may be used in sintering with magnetite concentrates as the major ore species.
基金supported by the National Basic Research Pro-gram of China (No. 2005CB422106)
文摘The Sinian-Lower Paleozoic (also called the lower association) in Sichuan (四川) basin has undergone geologic evolution for several hundred million years. The subsidence history of the Sinian-Lower Paleozoic can be divided into four stages: the stable subsidence during Cambrian and Silurian; the uplift and denudation during Devonian and Carboniferous; the subsidence (main process) during Permian to Late Cretaceous; and the rapid uplift and denudation since Late Cretaceous. The later two stages could be regarded as critical factors for the development of oil and gas in the lower association. The evolution of energy field such as temperature, pressure, and hydrocarbon phase in the lower association during the deep burial and uplift in the third stage might be induced as follows: (1) super-high pressure was developed during oil-cracking, previous super-high pressure was sustained, or changed as normal pressure during late uplift; (2) temperature increased with deep burial during persistent subsidence and decreased during uplift in late stage; (3) as a response to the change of the energy field, hydrocarbon phase experienced a series of changes such as organic material (solid), oil (liquid), oil-cracking gas (gaseous) + bitumen (solid) + abnormal high pressure, gas cap gas with super-high pressure (gaseous) + bitumen (solid) + water soluble gas (liquid), and gas in pool (gaseous) + water soluble gas (liquid) + bitumen (solid). The restoration of hydrocarbon phase evolution is of important value for the exploration of natural gas in the Sinian-Lower Paleozoic in Sichuan basin.
基金the National Natural Science Foundation of China(Grant nos.51672226,51772239)the Fundamental Research Funds for the Central Universities(XJTU).
文摘In the present work,the nature of phase evolution of(1x)(Na_(0.5)Bi_(0.5))TiO_(3)-xSrTiO_(3)(NBT-xST)solid solutions with x of 0e0.6 is revealed by characterizing the dielectric and ferroelectric properties.Two unique dielectric anomalies associated with high-temperature nanoregions(PNRs)in the ergodic relaxor(ER)state and low-temperature PNRs in the nonergodic relaxor(NR)state are identified.Characteristic temperatures,including TB,TRT*,Tm,Td and TT*,are determined in fresh and poled states on the basis of the characteristics of the evolution of these two dielectric anomalies.The whole evolution of the transition from the NR state to the ER state is reflected by the temperature-dependent polarization versus electric field(P-E)hysteresis loops,i.e.,from the square loops,via the double-like loops,to the slim loops.The characteristic temperatures,including TP-N,TN-R and TR-dis,are determined by the characteristics of the evolution of P-E loops.Accordingly,a phase diagram of NBT-xST was constructed according to these characteristic temperatures.Most importantly,the relationship between polarization responses and heterogeneous polar phase coexistence has been established and a schematic diagram is given.This work will help to understand the phase evolution and its impact on the macroscopic properties of NBT and the associated NBT-based solid solutions.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51772239 and 51761145024)the Fundamental Research Funds for the Central Universities(XJTU)。
文摘Owing to the complex composition architecture of these solid solutions,some fundamental issues of the classical(1-x)(Bi_(1/2)Na_(1/2))TiO_(3) -x(Bi_(1/2)K_(1/2))TiO_(3)(BNT-xBKT)binary system,such as details of phase evolution and optimal Na/K ratio associated with the highest strain responses,remain unresolved.In this work,we systematically investigated the phase evolution of the BNT-xBKT binary solid solution with x ranging from 0.12 to 0.24 using not only routine X-ray diffraction and weak-signal dielectric characterization,but also temperature-dependent polarization versus electric field(P-E)and current versus electric field(I-E)curves.Our results indicate an optimal Na/K ratio of 81/19 based on high-field polarization and elec-trostrain characterizations.As the temperature increased above 100?C,the x¼0.19 composition pro-duces ultrahigh electrostrains(>0.5%)with high thermal stability.The ultrahigh and stable electrostrains were primarily due to the combined effect of electric-field-induced relaxor-to-ferroelectric phase tran-sition and ferroelectric-to-relaxor diffuse phase transition during heating.More specifically,we revealed the relationship between phase evolution and electrostrain responses based on the characteristic tem-peratures determined by both weak-field dielectric and high-field ferroelectric/electromechanical property characterizations.This work not only clarifies the phase evolution in BNT-xBKT binary solid solution,but also paves the way for future strain enhancement through doping strategies.
基金supported by National Natural Science Foundation of China(11204258)National Science Foundation for Distinguished Young Scholars of Fujian Province(2012J06024)+3 种基金Science and Technology Plan of Xiamen City(3502Z201512363502Z20153018)Outstanding Young Scientific Research Personnel Training Plan in Colleges and Universities of Fujian Province(JA13229)Program for New Century Excellent Talents in University of Fujian Province(ZA14228)
文摘Using a hydrothermal method, by adjusting the reactant ratios, the hydrothermal temperatures, the hydrothermal time, and the pH values of prepared solutions, 1 mol.% Eu3+ doped K-Lu-F system optical materials were synthesized under control. For com- parison, the sample was also synthesized by a co-precipitation method. The X-ray diffraction (XRD) results suggested that the final crystalline phases had great relations with the hydrothermal synthesis conditions. The field emission scanning electron microscopy (FE-SEM) images and the energy-dispersive spectroscopy (EDS) patterns indicated that the morphologies and the components of some representative samples also varied with the synthesis conditions. Eu3+, acting as a probe, exhibited different optical proper- ties in the K-Lu-F system optical materials, which also indirectly proved the phase evolution of the final products. The results sug- gested that there were many crystalline phases with different symmetry in the K-Lu-F system. They would be good host matrices for the emitters.
基金supported by the National Natural Science Foundation of China(Grant Nos.51839009 and 51679017)。
文摘Natural gas-hydrates are valuable energy resource with rich deposits,and their thermal transport and thermal dynamic mechanical behaviors significantly affect the long-term production process and phase change-based thermal energy storage characteristics of these energy resources.This paper aims to propose novel relations to predict the thermophysical properties,to investigate the hydrate phase evolution in microstructures,and to study the thermal transport and thermal dynamic mechanical properties.Hydrates formation experiments in sandpack samples and ultrasonic wave tests are conducted with the aid of X-ray CT imaging.Digitalization microstructures models and variables are defined to describe the hydrate phase evolution,and novel relations are proposed to accurately predict the thermophysical properties based on the microporosity and ultrasonic wave velocities.The thermal transport and thermal dynamic mechanical properties in microstructures with hydrate,water,residuary pore and grain phases are studied.Results show that the average errors of porosity,P-wave and S-wave velocities between the experimental data and computed results by the proposed relations are less than 5%,indicating the accuracy and reliability of the proposed method.The temperature fraction decreases with increasing underground temperature and decreasing hydrate saturation.The thermal stress and thermal displacement increase as temperature and hydrate saturation increase.There are strong anisotropy for the temperature fraction,thermal stress and thermal displacement during the thermal transport of hydrates.
基金supported by the Natural Science Foundation of China(5207123251871165)。
文摘Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anode of the Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies(Ov-BMO-Cu)are in-situ generated by phase separation and hydrogen etching using nanoporous Cu-Mn alloy as selfsacrificial templates.On this basis,we have elucidated the relationship between the phase evolution,oxygen vacancies and sodium-ion storage mechanisms,further demonstrating the evolution of oxygen vacancies and the inhibition effect of manganese oxides as an“anchor”on grain aggregation of copper oxides.The kinetic analyses confirm that the expanded lattice space and increased oxygen vacancies of cycled Ov-BMO-Cu synergistically guarantee effective sodium-ion diffusion and storage mechanisms.Therefore,the Ov-BMO-Cu electrode exhibits higher reversible capacities of 4.04 mA h cm^(-2)at 0.2 mA cm^(-2)after 100 cycles and 2.20 m A h cm^(-2)at 1.0 mA cm^(-2)after 500 cycles.Besides,the presodiated Ov-BMO-Cu anode delivers a considerable reversible capacity of 0.79 m A h cm^(-2)at 1.0 mA cm^(-2)after 60 cycles in full cells with Na_(3)V_(2)(PO_(4))_(3)cathode,confirming its outstanding practicality.Thus,this work is expected to provide enlightenment for designing high-capacity bimetallic oxide anodes.
基金Sponsored by National Science Foundation for Young Scientists of China(51404118)Yunnan Province Science Youth Experts Fund of China(2012FD012)Yunnan Province Department of Education Fund of China(2012Y530)
文摘Thermodynamic analysis of refractory siderite ore during carbothermic reduction was conducted. Micro- structure characteristics and phase transformation of siderite ore during sodium-carbonate-added catalyzing carboth- ermic reduction were investigated. X-ray diffraction (XRD), scanning electron microscopy and energy-dispersive analysis of X rays were used to characterize the reduced samples. Results indicate that the solid reaction between FeO and SiO2 is inevitable during carbothermic reduction and the formation of fayalite is the main hindrance to the rapid reduction of siderite. The phase transformation of present siderite ore can be described as: siderite-magnetite-metallic iron, complying with the formation of abundant fayalite. Improving the reduction temperature (-1050 -C ) and duration is helpful for the formation and aggregation of metallic iron. The iron particle size in the reduced ore was below 20 l-m, and fayalite was abundant in the absence of sodium carbonate. With 5% Na2CO3 addition, the iron particle size in the reduced ore was generally above 50μm, and the diffraction intensity associated with metallic iron in the XRD pattern increased. The Na2O formed from the dissociation of Na2 CO3 can catalyze the carbothermie reduction of the siderite. This catalytic activity may be mainly caused by an increase in the reducing reaction activity of FeO.
基金financially supported by the National Natural Science Foundation of China (No.51472015)
文摘Binary immiscible Al-Sn alloy is a very important potential anode material for lithium ion batteries.The phase stability and separation process of Al-Sn film,fabricated by magnetron co-sputtering method,was investigated by X-ray diffractometer(XRD),differential scanning calorimetry(DSC) and in situ transmission electron microscopy(TEM) and explained by Miedema theoretical model.Thermodynamic analysis reveals that the asdeposited Al-Sn film will decompose spontaneously into Al-riched areas and Sn-riched areas because of the positive mixing enthalpy.The crystallization process takes place when the Al content in the Al-riched area or Sn content in the Sn-riched area increases.Experimental results show that Al-Sn thin film is composed of an amorphous matrix and well-dispersed composite nanoparticles.Every particle contains an Al-riched area and a Sn-riched area.The Snriched area crystallizes and swallows up the Al-riched area gradually during heating through uphill diffusion of the Sn atoms.Based on the theoretical analysis and experimental results,an empirical model to explain the phase evolution process in the Al-Sn film was proposed.
文摘Li-rich Li[Li0.2Mn0.54Ni0.13Co0.13]02(LMNC) powders were synthesized by a gel-combustion method. The related microstructure, electrochemical performance and electrochemically induced phase evolution were characterized. The 900℃ calcined powders have a hexagonal layered structure with high ordered degree and low cationic mixing level. The calcined materials as cathode electrode for Li-ion battery deliver the high electrochemical properties with an initial discharge capacity of 243.5 mA. h. g-1 at 25 mA.g-1 and 249.2 mA-h.g-1 even after 50 cycles. The electrochemically induced phase evolution investigated by a transmission electron microscopy indicates that Li+ ions deintercalated first from the LiMO2 (M = Mn, Co, Ni) component and then from Li2MnO3 component in the LMNC during the charge process, while Li+ ions intercalated into Li1-xMO2 component followed by into MnO2 component during the discharge process.
基金National Natural Science Foundation of China (Nos. 51271143 and 51302247)
文摘This paper systematically reports the thermodynamic characteristic and phase evolution of immiscible Cr–Mo binary alloy during mechanical alloying(MA) process. The Cr–35Mo(in at%) powder mixture was milled at 243 and258 K, respectively, for different time. For comparative study, Cr–15Mo and Cr–62Mo powder mixtures were milled at 243 K for 18 h. Solid solution Cr(Mo) with body-centered cubic(bcc) crystal structure and amorphous Cr(Mo) alloy was obtained during MA process caused by high-energy ball milling. Based on the Miedema's model, the free-energy change for forming either a solid solution or an amorphous in Cr–Mo alloy system is positive but small at a temperature range between 200 and 300 K. The thermodynamical barrier for forming alloy in Cr–Mo system can be overcome when MA occurs at 243 K, and the supersaturated solid solution crystal nuclei with bcc structure form continually, and three supersaturated solid solutions of Cr–62Mo, Cr–35Mo and Cr–15Mo formed. Milling the Cr–35Mo powder mixture at 258 K, the solid solution Cr(Mo) forms firstly, and then the solid solution Cr(Mo) transforms into the amorphous Cr(Mo)alloy with a few of nanocrystallines when milling is prolonged. At higher milling temperature, it is favorable for the formation of the amorphous phase, as indicated by the thermodynamical calculation for immiscible Cr–Mo alloy system.
基金This study was supported by the National Basic Research Program of China (No. 2004CB720206) the National Natural Science Foundation of China (No. 49971009)the RGC (HKU 7243/04H) Grant of the HKSAR and the Chinese Academy of Sciences (No. KZCX2-SW-118)
文摘Studies of lithology, sedimentary facies and the distribution regularity of SiO2 and Al2O3 contents and Al2O3/SiO2 ratio allow us to divide the Upper Pleistocene-Holocene Series represented by the MUanggouwan section in China's Salawnsu River valley into six segments: MGS1, MGS2, MGS3, MGS4, MGS5 and MGS6. The boundary ages for MGS1 (the Dishaogouwan and Dagouwan Formations), MGS2 (the upper Chengchuan Formation), MGS3 (the middle Chengchuan Formation), MGS4 (the lower Chengchuan Formation), MGS5 (most strata of the Salawusu Formation) and MGS6 (the bottom of the Salawusu Formation and the top of the Lishi Formation) correspond to those of MIS1, MIS2, MIS3, MIS4, MISS and MIS6, respectively, from deep sea sediments or continental glaciers. MGS5 can be subdivided into five subsegments (MGS5a, MGS5b, MGS5c, MGS5d and MGS5e) and the boundary ages of these subsegments correspond to those of MISSa, MISSb, MIS5c, MIS5d and MIS5e, respectively. Based on the paleoenvironment and paleoecology indicated by the primary chemical elements, fossil vertebrates, mollusks and pollen grains, we hypothesize that MGS1, MGS2, MGS3, MGS4, MGS5 and MGS6 and the subsegments of MGS5 match the corresponding stages for oxygen isotopes in the deep sea sediments and continental glaciers, and the substages of MIS5 in terms of climatic characters, further explaining the phenomena that determined the formation of the late Quaternary strata and the paleontology of the Salawusu River valley. These phenomena relate to fluctuations in the global climate (and particularly in the East Asian monsoon) during the glacial and interglacial periods.
基金Supported by the National Natural Science Foundation of China under Grant No 11704161the Natural Science Foundation of Jiangsu Province under Grant Nos BK20170309 and BK20151172the Changzhou Science and Technology Bureau under Grant Nos CJ20159049 and CJ20160028
文摘We elucidate the importance of a capping layer on the structural evolution and phase change properties of carbondoped Ge2 Sb2 Te5(C-GST) films during heating in air. Both the C-GST films without and with a thin SiO2 capping layer(C-GST and C-GST/SiO2) are deposited for comparison. Large differences are observed between C-GST and C-GST/SiO2 films in resistance-temperature, x-ray diffraction, x-ray photoelectron spectroscopy,Raman spectra, data retention capability and optical band gap measurements. In the C-GST film, resistancetemperature measurement reveals an unusual smooth decrease in resistance above 110℃ during heating. Xray diffraction result has excluded the possibility of phase change in the C-GST film below 170℃. The x-ray photoelectron spectroscopy experimental result reveals the evolution of Te chemical valence because of the carbon oxidation during heating. Raman spectra further demonstrate that phase changes from an amorphous state to the hexagonal state occur directly during heating in the C-GST film. The quite smooth decrease in resistance is believed to be related with the formation of Te-rich GeTe4-n Gen(n = 0, 1) units above 110℃ in the C-GST film. The oxidation of carbon is harmful to the C-GST phase change properties.
基金Project supported by the National Magnetic Confinement Fusion Energy Research Project of China(Grant No.2015GB118001)the Fundamental Research Funds for the Central Universities,China(Grant No.DUT16RC(3)052)+1 种基金the National Basic Research Program of China(Grant No.2012CB619402)the NETL Project(Grant No.DE-FE0027776)
文摘A series of material parameters are derived from atomistic simulations and implemented into a phase field(PF) model to simulate void evolution in body-centered cubic(bcc) iron subjected to different irradiation doses at different temperatures.The simulation results show good agreement with experimental observations — the porosity as a function of temperature varies in a bell-shaped manner and the void density monotonically decreases with increasing temperatures; both porosity and void density increase with increasing irradiation dose at the same temperature. Analysis reveals that the evolution of void number and size is determined by the interplay among the production, diffusion and recombination of vacancy and interstitial.