Microstructure Characteristics and Possible Phase Evolution of the Coal Gangue-Steel Slag Ceramics Prepared by the Solid-State Reaction Methods

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.

Inkjet-Printing Controlled Phase Evolution Boosts the Efficiency of Hole Transport Material Free and Carbon-Based CsPbBr_(3) Perovskite Solar Cells Exceeding 9%

Hole transport material free carbon-based all-inorganic CsPbBr_(3)perovskite solar cells(PSCs)are promising for commercialization due to its low-cost,high open-circuit voltage(V_(oc))and superior stability.Due to the different solubility of PbBr_(2)and CsBr in conventional solvents,CsPbBr_(3)films are mainly obtained by multi-step spin-coating through the phase evolution from PbBr_(2)to CsPb_(2)Br_(5)and then to CsPbBr_(3).The scalable fabrication of high-quality CsPbBr_(3)films has been rarely studied.Herein,an inkjet-printing method is developed to prepare high-quality CsPbBr_(3)films.The formation of long-range crystalline CsPb_(2)Br_(5)phase can effectively improve phase purity and promote regular crystal stacking of CsPbBr_(3).Consequently,the inkjet-printed CsPbBr_(3)C-PSCs realized PCEs up to 9.09%,8.59%and 7.81%with active areas of 0.09,0.25,and 1 cm^(2),respectively,demonstrating the upscaling potential of our fabrication method and devices.This high performance is mainly ascribed to the high purity,strong crystal orientation,reduced surface roughness and lower trap states density of the as-printed CsPbBr_(3)films.This work provides insights into the relationship between the phase evolution mechanisms and crystal growth dynamics of cesium lead bromide halide films.

Phase evolution of plasma sprayed Al_2O_3-13%TiO_2 coatings derived from nanocrystalline powders

Commercial nanosized alumina and titania particles were selected as raw materials to prepare the blended slurry with composition of A1203-13%TiO2 （mass fraction）, which were reconstituted into micrometer-sized granules by spray drying, subsequently sintering at different temperatures to form nanostructured feedstock for thermal spraying, and then A1203-13%TiO2 nanocoatings were deposited by plasma spraying. The evolution of morphology, microstructure, and phase transformation of the agglomerated powder and as-sprayed coatings were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results show that A1203 retains the same a phase as the raw material during sintering, while TiO2 changes from anatase to futile. During plasma spraying, some a-A1203 phases solidify to form metastable y-A1203, and the volume fraction of a-A1203 decreases as CPSP increases. However, peaks of the TiO2 phase are not observed from the as-sprayed coatings except for the coatings sprayed at the lower CPSP. As the CPSP increases, nanostructured TiO2 is dissolved easily in y-A1203 or z-A1203＇TiO2 phase. After heat treatment, y-A1203 in the coatings transforms to a-A1203, and rutile is precipitated.

Phase evolution and room temperature ferroelectric and magnetic properties of Fe-doped BaTiO_3 ceramics

To make the ferroelectric BaTiO3 possess ferromagnetism simultaneously,magnetic Fe was doped into BaTiO3 ceramics at doping levels up to 10%(molar fraction).Both tetragonal and hexagonal phases coexisted in the Fe-doped BaTiO3 ceramics except at 1% doping level.X-ray diffraction analysis indicated that higher doping level of Fe,higher sintering temperature and longer sintering time promoted the formation of hexagonal phases in Fe-doped BaTiO3 ceramics.Ferroelectricity was observed in all samples at room temperature,but it was greatly depressed by Fe doping.Except at doping level of 1%,room-temperature ferromagnetism was observed in the BaTiO3 ceramics.The dependence of the saturation magnetization and coercivities of the Fe-doped BaTiO3 ceramics on doping level was systematically studied.Both the saturation magnetization and magnetic coercivities were found to be dependent on the doping level as well as the fraction of the hexagonal phase in the ceramics.

TEM observation of precipitation phase produced during tempering of steel AerMet100 and first principles calculations of phase evolution

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.

Phase evolution in AlSi20/8009 aluminum alloy during high temperature heating near melting point and cooling processes

The AlSi20/8009 aluminum alloy was heated to high temperatures near the melting point and cooled to investigate the effect of external Si addition on the phase evolution of Al12(Fe,V)3 Si dispersion. Differential scanning calorimeter, scanning electron microscope, energy dispersive spectrometer and X-ray diffractometer were employed.The results showed that Al12(Fe,V)3 Si and Si phases evolved into a needle-like Al4.5 Fe Si phase and a nano-sized V-rich phase during holding the alloy at 580-600℃. With increasing holding temperature to 620-640℃, Al4.5 Fe Si and nano-sized V-rich phases evolved reversibly into Al12(Fe,V)3 Si and Si phases, of which Al12(Fe,V)3 Si occupied a coarse and hexagonal morphology. During the alloy(after holding at 640 ℃) furnace cooling to 570 ℃ or lower, Si and Al12(Fe,V)3 Si phases evolved into strip-like Al4.5 Fe Si and the V-rich phases, which is a novel formation route for Al4.5 Fe Si phase different from Al-Fe-Si ternary system.

Phase Evolution and Magnetic Studies of La and Refractory Metals Co-substituted α-Fe/R_2Fe_(14)B-type Nanocomposites

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.

Phase Evolution Study and Optimization of the Heat Treatment Process for High Current Capacity Bi-2223 Tapes

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.

Phase evolution and mechanical properties of low-activation refractory high-entropy alloy Ti_(1.5)ZrV_(0.5)Ta_(0.5)

A novel low-activation Ti_(1.5)ZrV_(0.5)Ta_(0.5)refractory high-entropy alloy(RHEA)was designed as a potential candidate for nuclear reactor application.At room temperature,it had an elongation of 8.4%and a yield strength of 1096 MPa.The phase evolution of this alloy and its effect on properties was investigated.At 400℃,the solid solution bcc 1 transformed into the fcc phase and bcc 2 phase,and theωphase andαphase also appeared.At 600℃,theωphase andαphase disappeared,and the microstructure of the alloy was composed of the fcc phase and bcc 2 phase.When the temperature was up to 1200℃,the fcc phase and bcc 2 phase re-transformed into solid solution bcc 1 phase.The precipitation ofωphase andαphase caused a sharp increase in strength and a decrease in plasticity.Meanwhile,the appearance of the fcc phase led to a simultaneous decrease in strength and ductility,due to larger stress concentrations at the fcc/bcc interface.Besides,the formation mechanism of each phase in the alloy was discussed in detail.

Quantifying structural distortion manipulation for desired perovskite phase:PartⅡ.Three-step workflow to reveal phase evolution logic

Distortion manipulation emerges as an efficient approach to obtain desired perovskite phases for various applications.In part I of this study,we propose a paradigm to quantify the structural distortion manipulation,which enables us to obtain desired perovskite phases by translating relevant materials research into a single mathematical question.As part II of this continuous study,we construct normalized structures by introducing all possible couplings of dominant distortions into a cubic supercell and then compare them with variously shaped primitive/conventional cells known in the database.The structure comparison demonstrates that distortions are the only cause for phase and property variations.This confirms that our proposed distortion parameters can be directly used to construct phases,providing theoretical support for the paradigm in Part I.Given the limited number of distortion types,we identify that the positional relations involved in distortion arrangements and couplings are the keys to describe numerous phases.Furtherly,a three-step workflow is proposed with core contents related to the positional relation,distortion hierarchy,and distortion-component-generation ordering in spatial dimension,respectively.The definition basis and value changes of distortion/model parameters in this workflow illustration provide guidelines about how to reveal the logic behind the perovskite phase evolution.

Phase Evolution and Glass Formation in an Fe-Based Alloy

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.

Phase evolution mechanism study and fabrication of PbMo_(6)S_(8) superconducting materials with two-step sintering process

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.

Mineralogical characteristics,metallurgical properties and phase structure evolution of Ca-rich hematite sintering

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.

Energy Field Adjustment and Hydrocarbon Phase Evolution in Sinian-Lower Paleozoic, Sichuan Basin

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.

Phase evolution in(1x)(Na_(0.5)Bi_(0.5))TiO_(3)-xSrTiO_(3) solid solutions:A study focusing on dielectric and ferroelectric characteristics

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.

Phase evolution and relaxor to ferroelectric phase transition boosting ultrahigh electrostrains in (1-x)(Bi_(1/2)Na_(1/2))TiO_(3)-x(Bi_(1/2)K_(1/2))TiO_(3) solid solutions

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.

Eu^(3+) doped K-Lu-F system optical materials: controlling synthesis, phase evolution, and optical properties

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.

Digital microstructure insights to phase evolution and thermal flow properties of hydrates by X-ray computed tomography

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.

Phase separation-hydrogen etching-derived Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies boosting superior sodium-ion storage kinetics

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.

Microstructure Characteristic and Phase Evolution of Refractory Siderite Ore during Sodium-carbonate-added Catalyzing Carbothermic Reduction

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.