Poly(_(L)-lactide)(PLLA),a leading biodegradable polyester,has demonstrated potential as a sustainable alternative,owing to its excellent biodegradability and rigidity.However,their slow crystallization kinetics and p...Poly(_(L)-lactide)(PLLA),a leading biodegradable polyester,has demonstrated potential as a sustainable alternative,owing to its excellent biodegradability and rigidity.However,their slow crystallization kinetics and poor heat resistance limit their application scope.Recent advances have highlighted that the combination of extensional flow and thermal fields can achieve toughness–stiffness balance,high transparency,and good heat resistance.However,the effect of extensional flow on the post-non-isothermal crystallization of PLLA during heating and the resulting crystalline texture remains unclear.In this study,PLLA with a heterogeneous amorphous structure and oriented polymorph was prepared by extensional flow.The effect of heterogeneous amorphous structures on non-isothermal crystallization kinetics during the heating process was studied by thermal analysis,polarized optical microscopy,infrared spectroscopy,and ex situ/in situ X-ray characterization.These results clearly illustrate that extensional flow enhances the formation of oriented crystalline structures,accelerates non-isothermal crystallization,and modulates the polymorphic composition of PLLA.Moreover,an unexpected dual cold-crystallization behavior is identified in ordered PLLA samples upon extensional flow,which is from the extensional flow-induced heterogeneous amorphous phase into α' phase(low-temperature peak)and the pristine amorphous phase intoαphase(high-temperature peak).The extensional flow primarily promotes the formation of the more perfectαandα'phases,but has a negative effect on the final content ofαphase formed after cold crystallization andα'-to-αphase transformation.The findings of this work advance the understanding of PLLA non-isothermal crystallization after extensional flow and offer valuable guidance for high-performance PLLA upon heat treatment in practical processing.展开更多
Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'...Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.展开更多
Four distinct coordination polymers(CPs)were successfully synthesized by altering solvent types and adjusting ligand concentrations,and their crystal structures were investigated.[Co(L)(FDCA)(H_(2)O)_(2)]·0.5H_(2...Four distinct coordination polymers(CPs)were successfully synthesized by altering solvent types and adjusting ligand concentrations,and their crystal structures were investigated.[Co(L)(FDCA)(H_(2)O)_(2)]·0.5H_(2)O(1)was synthesized as a 2D structure using Coas the metal source,methanol‑water(4∶6,V/V)as the solvent,and specific concentrations of 2,5‑furandicarboxylic acid(H_(2)FDCA)and 1,3,5‑triimidazole benzene(L).Adjusting to pure water and lowering the concentration of L yielded the 1D chain structure of[Co(HL)2(H_(2)O)_(2)](FDCA)_(2)·6H_(2)O(2).Using Cu(Ⅱ)as the metal source,methanol/water(9∶1,V/V)as the solvent,and specific concentrations of L and H2FDCA,the 1D chain structure of[Cu(L)(FDCA)(H_(2)O)]·2H_(2)O(3)was synthesized.Upon increasing the concentrations of L and H2FDCA,and switching the solvent to pure water,the 1D chain structure of[Cu(HL)_(2)(H_(2)O)_(2)](FDCA)_(2)·6H_(2)O(4)was obtained.This shows that changing the solvent and ligand concentrations can affect the structural changes of CPs.In addition,the solid‑state photoluminescence of CPs 1‑4 at room temperature was studied,and their morphological changes were observed via scanning electron microscopy.Density functional theory calculations revealed that the negative charge concentrates on the O and N atoms of the ligand,facilitating ligand‑metal ion coordination.CCDC:2403934,1;2403935,2;2403936,3;2403938,4.展开更多
Mg65Cu25Y10 bulk amorphous alloy specimens prepared by conventional copper mould method were heated at 200 °C for different time and the phase contents as well as microstructure were studied.The XRD results show ...Mg65Cu25Y10 bulk amorphous alloy specimens prepared by conventional copper mould method were heated at 200 °C for different time and the phase contents as well as microstructure were studied.The XRD results show that the crystallization of Mg65Cu25Y10 bulk amorphous alloy specimen becomes complete as the treating time increases and Mg2Cu,Mg24Y5 and HCP-Mg crystalline phases are found.Snowflake-like morphology is found in different specimens through SEM observation.The EDS patterns show that the composition of the snowflake-like structure is close to that of the as-cast alloy.Laminated structures are observed from the TEM images of the snowflake-like structure.From the electron diffraction patterns,it is seen that the snowflake-like structure is the combination of Mg24Y5 and amorphous matrix.The FCC-Mg phase in the matrix transforms into HCP-Mg during the heat-treating process.展开更多
Recent advances in geoscience have underscored the critical role of abiogenic processes in petroleum formation,especially the formation and polymerization of methane.However,whether a direct carbon-H_(2) reaction can ...Recent advances in geoscience have underscored the critical role of abiogenic processes in petroleum formation,especially the formation and polymerization of methane.However,whether a direct carbon-H_(2) reaction can produce C_(2+)hydrocarbons(e.g.,ethane and propane)beyond methane remains an open question.Here,we demonstrate the direct synthesis of ethane and propane via reactions between amorphous carbon and H_(2) under upper mantle conditions(2-10 GPa and 800-1200℃).A systematic investigation reveals that increasing structural disorder in carbon precursors,from graphite to glassy carbon-Ⅱ and carbon black,enhances the production of C_(2)-C_(3) hydrocarbons.Through integrated X-ray diffraction and reverse Monte Carlo simulations,we establish that the continuous random atomic network structures in amorphous carbon enable one-step synthesis of heavy hydrocarbons with H_(2).These models establish a direct link between atomic-scale carbon structures and the one-step synthesis of C_(2+) hydrocarbons under H_(2)-rich,high-pressure,and high-temperature conditions—potentially revealing an efficient mechanism for the abiotic production of C_(2+) hydrocarbons in the upper mantle.展开更多
Lithium manganese silicate(Li-Mn-Si-O)cathodes are key components of lithium-ion batteries,and their physical and mechanical properties are strongly influenced by their underlying crystal structures.In this study,a ra...Lithium manganese silicate(Li-Mn-Si-O)cathodes are key components of lithium-ion batteries,and their physical and mechanical properties are strongly influenced by their underlying crystal structures.In this study,a range of machine learning(ML)algorithms were developed and compared to predict the crystal systems of Li-Mn-Si-O cathode materials using density functional theory(DFT)data obtained from the Materials Project database.The dataset comprised 211 compositions characterized by key descriptors,including formation energy,energy above the hull,bandgap,atomic site number,density,and unit cell volume.These features were utilized to classify the materials into monoclinic(0)and triclinic(1)crystal systems.A comprehensive comparison of various classification algorithms including Decision Tree,Random Forest,XGBoost,Support VectorMachine,k-Nearest Neighbor,Stochastic Gradient Descent,Gaussian Naive Bayes,Gaussian Process,and Artificial Neural Network(ANN)was conducted.Among these,the optimized ANN architecture(6–14-14-14-1)exhibited the highest predictive performance,achieving an accuracy of 95.3%,aMatthews correlation coefficient(MCC)of 0.894,and an F-score of 0.963,demonstrating excellent consistency with DFT-predicted crystal structures.Meanwhile,RandomForest and Gaussian Processmodels also exhibited reliable and consistent predictive capability,indicating their potential as complementary approaches,particularly when data are limited or computational efficiency is required.This comparative framework provides valuable insights into model selection for crystal system classification in complex cathode materials.展开更多
Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled t...Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled thermomechanical fields remains insufficiently understood.In this study,transmission and scanning electron microscopy were employed to observe dislocation structures and grain boundary heterogeneities in processed aluminum alloys,suggesting stress concentrations and microstructural inhomogeneities associated with vacancy accumulation.To complement these observations,first-principles calculations and molecular dynamics simulations were conducted for seven single-vacancy configurations in face-centered cubic aluminum.The stress response,total energy,density of states(DOS),and differential charge density were examined under varying compressive strain(ε=0–0.1)and temperature(0–600 K).The results indicate that face-centered vacancies tend to reduce mechanical strength and perturb electronic states near the Fermi level,whereas corner and edge vacancies appear to have weaker effects.Elevated temperatures may partially restore electronic uniformity through thermal excitation.Overall,these findings suggest that vacancy position exerts a critical but position-dependent influence on coupled structure-property relationships,offering theoretical insights and preliminary experimental support for defect-engineered aluminum alloy design.展开更多
Lithium-ion batteries with LiCoO_(2)(LCO)cathodes are widely used in various electronic devices,resulting in a large amount of spent LCO(SLCO).Therefore,there is an urgent need for an efficient technique for recycling...Lithium-ion batteries with LiCoO_(2)(LCO)cathodes are widely used in various electronic devices,resulting in a large amount of spent LCO(SLCO).Therefore,there is an urgent need for an efficient technique for recycling SLCO.However,due to the presence of cobalt oxide with a spinel phase on the surface of highly-degraded LCO,the strong electrostatic repulsion from the transition metal octahedron poses a high Li replenishment barrier,making the regeneration of highly-degraded LCO a challenge.Herein,we propose a structural transformation strategy for reconstructing Li replenishment channels to aid the direct regeneration of highly-degraded LCO.In this approach,ball milling is employed to disrupt the inherent structure of highly-degraded LCO,thereby releasing the internal stress and converting the surface spinel phase into a homogeneous amorphous structure,which promotes Li insertion and regeneration.The regenerated LCO(RLCO)exhibits an outstanding discharge capacity of 179.10 mAh·g^(−1) in the voltage range of 3.0–4.5 V at 0.5 C.The proposed strategy is an effective regeneration approach for highly-degraded LCO,thereby facilitating the efficient recycling of spent lithium-ion battery cathode materials.展开更多
Noble metal-based intermetallic compounds(IMCs)with ordered atomic arrangements exhibit remarkable electrocatalytic activity owing to their unique crystal and electronic structures.During the past years,great advance ...Noble metal-based intermetallic compounds(IMCs)with ordered atomic arrangements exhibit remarkable electrocatalytic activity owing to their unique crystal and electronic structures.During the past years,great advance has been made in the development of noble metal-based IMCs.Recently,Lu and coworkers reported ultrathin“amorphous/intermetallic”(A/IMC)heterophase PtPbBi nanosheets(NSs)with a thickness of 2.5±0.3 nm.The oxidative etching effect caused by the coexistence of O_(2)and Br^(-)ions plays a crucial role in the formation of the IMC and unique two-dimensional structure with irregular shapes and curled edges.This study shows that fabricating an A/IMC heterophase structure with a multimetallic composition can effectively enhance the catalytic performances of noble metal-based electrocatalysts.展开更多
Pr-based bulk metallic amorphous （BMA） rods （Pr60Ni30Al10） and Al-based amorphous ribbons （Al87Ni10Pr3） have been prepared by using copper mould casting and single roller melt-spun techniques, respectively. Ther...Pr-based bulk metallic amorphous （BMA） rods （Pr60Ni30Al10） and Al-based amorphous ribbons （Al87Ni10Pr3） have been prepared by using copper mould casting and single roller melt-spun techniques, respectively. Thermal parameters deduced from differential scanning calorimeter （DSC） indicate that the glass-forming ability （GFA） of Pr60Ni30Al10 BMA rod is far higher than that of Al87Ni10Pr3 ribbon. A comparative study about the differences in structure between the two kinds of glass-forming alloys, superheated viscosity and crystallization are also made. Compared with the amorphous alloy Al87Ni10Pr3, the BMA alloy Pr60Ni30Al10 shows high thermal stability and large viscosity, small diffusivity at the same superheated temperatures. The results of x-Ray diffraction （XRD） and transmission electron microscope （TEM） show the pronounced difference in structure between the two amorphous alloys. Together with crystallization results, the main structure compositions of the amorphous samples are confirmed. It seems that the higher the GFA, the more topological type clusters in the Pr-Ni-Al amorphous alloys, the GFAs of the present glass-forming alloys are closely related to their structures.展开更多
The effect of structural order in the parent alloy substrate on the oxidation kinetics and oxide phase evolution was investigated for the thermal oxidation of amorphous Cu33at.%Zr67at.%and crystalline CuZr2 alloys of ...The effect of structural order in the parent alloy substrate on the oxidation kinetics and oxide phase evolution was investigated for the thermal oxidation of amorphous Cu33at.%Zr67at.%and crystalline CuZr2 alloys of identical compositions in the temperature range of 200–250?C.It was found that,besides the strong preferential oxidation of Zr in both alloys,the lack of structural order in the amorphous Cu33at.%Zr67at.%alloy results in much slower oxidation kinetics,as well as in distinctly different microstructures of the oxide overgrowth and its Zr-depletion zone in the wake of the ZrO2 overlayer growth front.The experimental findings can be rationalized on the basis of the strikingly different atomic mobilities of Cu,Zr and dissolved O in the amorphous and crystalline alloys,which also results in different nucleation barriers for crystalline oxide nucleation.The thus obtained knowledge on the underlying oxidation mechanisms provides new and profound insights into the surface engineering of metallic alloys.展开更多
The formation,thermal stability,crystallized structure,and magnetic properties of melt-spun Co80-xSmxB20(x=0–20)amorphous alloys have been investigated.A single amorphous phase is formed for the alloys with x=0–15.T...The formation,thermal stability,crystallized structure,and magnetic properties of melt-spun Co80-xSmxB20(x=0–20)amorphous alloys have been investigated.A single amorphous phase is formed for the alloys with x=0–15.The first crystallization temperature gradually increases from 670 to 955 K as x increases from 0 to 10,and decreases to 836K when x=15.After optimum annealing,the nanocomposite structure consisting of SmCo12B6+fcc-Co+Sm2Co17 phases is formed for the alloys with x=5 and 7.5,and SmCo12B6+Sm2Co17+SmCo3,SmCo12B6+Sm2Co17+SmCo4B,and SmCo12B6+SmCo4B phases are formed for the alloys with x=10,12.5,and 15,respectively.The coercivity of the annealed alloys increases remarkably from 103.5 to 1249.4 kA m^-1 as x increases from 5 to 15,while the magnetization at the applied field of 2.0T decreases from 0.51 to 0.16T.The improved magnetic hardness with rising Sm content is attributed to the formation of the hard magnetic phases with higher magnetocrystalline anisotropy and the increase in their volume fraction.展开更多
Zirconia-mullite nano-composite ceramics were fabricated by in-situ controlled crystallization of Si-Al-Zr-O amorphous bulk, which were first treated at 900-1000 ℃ for nucleation, then treated at higher temperature f...Zirconia-mullite nano-composite ceramics were fabricated by in-situ controlled crystallization of Si-Al-Zr-O amorphous bulk, which were first treated at 900-1000 ℃ for nucleation, then treated at higher temperature for crystallization to obtain ultra-fine zirconia-mullite composite ceramics. The effects of treating temperature and ZrO2 addition on mechanical properties and microstructure were analyzed. A unique structure in which there are a lot of near equiaxed t-ZrO2 grains and fine yield-cracks has been developed in the samples with 15% zirconia addition treated at 1 150 ℃ . This specific microstructure is much more effective in toughening ceramics matrix and results in the best mechanical properties. The flexural strength and fracture toughness are 520 MPa and 5.13 MPa·m1/2, respectively. Either higher zirconia addition or higher crystallization temperature will produce large size rod-like ZrO2 and mullite grains, which are of negative effect on mechanical properties of this new composite ceramics.展开更多
The amorphous and crystal structures of Zr 41 Ti 14 Ni 10 Cu 12.5 Be 22.5 alloy have been analyzed with X ray diffractometer. The structures of bulk amorphous Zr 41 Ti 14 Ni 10 Cu 12.5 B 22.5 alloy in solid, supercool...The amorphous and crystal structures of Zr 41 Ti 14 Ni 10 Cu 12.5 Be 22.5 alloy have been analyzed with X ray diffractometer. The structures of bulk amorphous Zr 41 Ti 14 Ni 10 Cu 12.5 B 22.5 alloy in solid, supercooled liquid and liquid states are almost of the same structure. The RDFs (Radius Distribution Function), the first coordination number, the first coordination radius, the correlation radius and atom number of the cluster were calculated for bulk amorphous Zr 41 Ti 14 Ni 10 Cu 12.5 B 22.5 alloy in different states. The first coordination sphere radii and the first coordination numbers are 0.312?nm, 11.2 in solid state, 0.301?nm, 10.932 in supercooled liquid region and 0.305?nm, 11.296 in liquid state. The crystal structure of Zr 41 Ti 14 Ni 10 Cu 12.5 B 22.5 alloy is consisted of several intermetallic compounds which are CuZr 2, Be 2Zr, etc. The reason of formation glass for this alloy is that there is a larger resistance for atoms to rearrange and form intermetallic compounds in a long range order.展开更多
A novel NiII complex [{Ni（IBG）（4,4＇-bipy）（H2O）2}·3H2O]n 1 （H2IBG = isophthaloylbisglycine and 4,4＇-bipy = 4,4＇-bipyridine） has been synthesized and characterized by singlecrystal X-ray diffraction, ele...A novel NiII complex [{Ni（IBG）（4,4＇-bipy）（H2O）2}·3H2O]n 1 （H2IBG = isophthaloylbisglycine and 4,4＇-bipy = 4,4＇-bipyridine） has been synthesized and characterized by singlecrystal X-ray diffraction, elemental analysis, IR spectra and thermogravimetric analysis. It crystallizes in monoclinic, space group P2/c with a = 15.5420（7）, b = 22.4344（1）, c = 8.3455（5）, β = 101.538（3）o, V = 2670.1（7）3, Z = 4, C22H32N4NiO13, Mr = 619.23, Dc = 1.443 g/cm3, F（000） = 1296.0, μ（MoKα） = 0.750 mm-1, the final R = 0.0570 and wR = 0.1445 for 2296 observed reflections with I 〉 2σ（I）. In the structure, the NiII metal center is coordinated in an octahedral environment arranged by two water molecules, two carboxylate oxygen atoms and two nitrogen atoms from two 4,4＇-bipy ligands. Thermal decomposition and powder X-ray diffraction results indicate that the transformation from the crystal form, [{Ni（IBG）（4,4＇-bipy）（H2O）2}·3H2O]n, to the amorphous powder, Ni（IBG）（4,4＇-bipy）（H2O）2, is reversible, so the latter form may be utilized as an absorbing agent for water and water vapor.展开更多
Anisotropic magnets were obtained by hot deformation with the partial crystallized precursor prepared via spark-plasma sintering （SPS）. Amorphous powders with the nominal composition of Nd_28.72Fe_balCo_5.66 Ga_0.59...Anisotropic magnets were obtained by hot deformation with the partial crystallized precursor prepared via spark-plasma sintering （SPS）. Amorphous powders with the nominal composition of Nd_28.72Fe_balCo_5.66 Ga_0.59B_0.92 （wt%） were used as the starting material. The results show that the amorphous powders would suffer varying degrees of crystallization even below the crystal- lization point during the SPS process under high pressure. And the pre-crystallized grains in precursors have great impacts on the microstructure and magnetic properties of the hot-deformed magnets. The final obtained anisotropic magnets exhibit homogeneous microstructure consisting of well-aligned and platelet-shaped Nd_2Fe_14B grains without abnormal growth. It can be found that a reasonable pro- portion of pre-crystallized gains could promote the pref- erential orientation in the magnet, leading to the achievement of optimal magnetic properties among the magnets with identical composition and best magnetic performance is achieved in the magnet hot deformed from the 490 ℃ high-pressure hot-pressed precursor.展开更多
Elemental powders of Al-24. 4 % Fe (mole fraction) alloy were mechanically-alloyed using a conventional type ball-milling. Not only Fe particles gradually disperse in Al matrix but also Al and Fe crystal grains are re...Elemental powders of Al-24. 4 % Fe (mole fraction) alloy were mechanically-alloyed using a conventional type ball-milling. Not only Fe particles gradually disperse in Al matrix but also Al and Fe crystal grains are refined to the order of ten nanometers after ball-milling for 180 h. The am0rphization starts at the early stage of ball milling and proceeds gradually. Complete amorphization is confirmed by ball-milling for 720h. The amorphization of the Powders after ball-milled for 180 h can be promoted by heating up to 673 K,which suggests a possibility of producing amorphous material by appropriate ball-milling and subsequent heating.展开更多
The mixture model of Al_(85)Y_4Nd_4Ni_7 alloy in which a partiallycrystallized amorphous alloy is regarded as a nanocornposite of an Al nanoparticle and a remainingamorphous matrix is presented. Its evolution in the p...The mixture model of Al_(85)Y_4Nd_4Ni_7 alloy in which a partiallycrystallized amorphous alloy is regarded as a nanocornposite of an Al nanoparticle and a remainingamorphous matrix is presented. Its evolution in the process of crystallization has been investigatedby differential scanning calorimetry (DSC), X-ray diffraction (XRD), and transmission electronmicroscopy (TEM). Mainly amorphous structure with alpha-Al nanocrystals embedded in the amorphousmatrix has been revealed by melt spining the alloy. Crystallization is showed to occur in threestages: (1) crystallization of amorphous alloy and formation of AINiY, AINdNi and unknowncrystalline phases, (2) formation of Al_3 Y and Al_3Nd, and (3) formation of Al_3Ni.展开更多
The crystallization behaviour of amorphous Al_(85)Ni_(10)Y_(5) alloy under high pressure was investigated.Results showed that the amorphous state can be preserved when the alloy is treated under high pressure at tempe...The crystallization behaviour of amorphous Al_(85)Ni_(10)Y_(5) alloy under high pressure was investigated.Results showed that the amorphous state can be preserved when the alloy is treated under high pressure at temperature below 325℃,the polytropic crystallization takes place when the alloy is treated at 325〜520 ℃ and 3〜6GPa for 1 min;the crystallizing product is nanometer scale supersaturated fee-Al solid solution particles dispersed in amorphous matrix;under 1 GPa pressure amorphous allloy crystallizes in an eutectic way,the crystallizing products are fee-Al,Al_(3)Y,Al_(3)Ni,AlNiY equilibrium crystalline phases etc.High pressure appreciably changes the crystallization mode and the products,elevates the crystallizing temperature.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U23A20583,52033005,U21A2090,and 52173040)Department of Science and Technology of Sichuan Province(No.2024NSFTD0003)。
文摘Poly(_(L)-lactide)(PLLA),a leading biodegradable polyester,has demonstrated potential as a sustainable alternative,owing to its excellent biodegradability and rigidity.However,their slow crystallization kinetics and poor heat resistance limit their application scope.Recent advances have highlighted that the combination of extensional flow and thermal fields can achieve toughness–stiffness balance,high transparency,and good heat resistance.However,the effect of extensional flow on the post-non-isothermal crystallization of PLLA during heating and the resulting crystalline texture remains unclear.In this study,PLLA with a heterogeneous amorphous structure and oriented polymorph was prepared by extensional flow.The effect of heterogeneous amorphous structures on non-isothermal crystallization kinetics during the heating process was studied by thermal analysis,polarized optical microscopy,infrared spectroscopy,and ex situ/in situ X-ray characterization.These results clearly illustrate that extensional flow enhances the formation of oriented crystalline structures,accelerates non-isothermal crystallization,and modulates the polymorphic composition of PLLA.Moreover,an unexpected dual cold-crystallization behavior is identified in ordered PLLA samples upon extensional flow,which is from the extensional flow-induced heterogeneous amorphous phase into α' phase(low-temperature peak)and the pristine amorphous phase intoαphase(high-temperature peak).The extensional flow primarily promotes the formation of the more perfectαandα'phases,but has a negative effect on the final content ofαphase formed after cold crystallization andα'-to-αphase transformation.The findings of this work advance the understanding of PLLA non-isothermal crystallization after extensional flow and offer valuable guidance for high-performance PLLA upon heat treatment in practical processing.
文摘Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.
文摘Four distinct coordination polymers(CPs)were successfully synthesized by altering solvent types and adjusting ligand concentrations,and their crystal structures were investigated.[Co(L)(FDCA)(H_(2)O)_(2)]·0.5H_(2)O(1)was synthesized as a 2D structure using Coas the metal source,methanol‑water(4∶6,V/V)as the solvent,and specific concentrations of 2,5‑furandicarboxylic acid(H_(2)FDCA)and 1,3,5‑triimidazole benzene(L).Adjusting to pure water and lowering the concentration of L yielded the 1D chain structure of[Co(HL)2(H_(2)O)_(2)](FDCA)_(2)·6H_(2)O(2).Using Cu(Ⅱ)as the metal source,methanol/water(9∶1,V/V)as the solvent,and specific concentrations of L and H2FDCA,the 1D chain structure of[Cu(L)(FDCA)(H_(2)O)]·2H_(2)O(3)was synthesized.Upon increasing the concentrations of L and H2FDCA,and switching the solvent to pure water,the 1D chain structure of[Cu(HL)_(2)(H_(2)O)_(2)](FDCA)_(2)·6H_(2)O(4)was obtained.This shows that changing the solvent and ligand concentrations can affect the structural changes of CPs.In addition,the solid‑state photoluminescence of CPs 1‑4 at room temperature was studied,and their morphological changes were observed via scanning electron microscopy.Density functional theory calculations revealed that the negative charge concentrates on the O and N atoms of the ligand,facilitating ligand‑metal ion coordination.CCDC:2403934,1;2403935,2;2403936,3;2403938,4.
基金Project (2008-04) supported by the Top Talent Plan of Jiangsu University, ChinaProject (10KJA430008) supported by the Natural Science Foundation of Jiangsu Higher Education Institutions,China
文摘Mg65Cu25Y10 bulk amorphous alloy specimens prepared by conventional copper mould method were heated at 200 °C for different time and the phase contents as well as microstructure were studied.The XRD results show that the crystallization of Mg65Cu25Y10 bulk amorphous alloy specimen becomes complete as the treating time increases and Mg2Cu,Mg24Y5 and HCP-Mg crystalline phases are found.Snowflake-like morphology is found in different specimens through SEM observation.The EDS patterns show that the composition of the snowflake-like structure is close to that of the as-cast alloy.Laminated structures are observed from the TEM images of the snowflake-like structure.From the electron diffraction patterns,it is seen that the snowflake-like structure is the combination of Mg24Y5 and amorphous matrix.The FCC-Mg phase in the matrix transforms into HCP-Mg during the heat-treating process.
基金mainly supported by the Natural Science Foundation of China (Grant Nos. 52288102, 52090020, and 52372261)the Natural Science Foundation of Hebei Province (Grant No. E202403045)+1 种基金the S&T Program of Hebei (Grant No. 225A1102D)the Ministry of Education Chang Jiang Scholar Professor Program (Grant No. T2022241)
文摘Recent advances in geoscience have underscored the critical role of abiogenic processes in petroleum formation,especially the formation and polymerization of methane.However,whether a direct carbon-H_(2) reaction can produce C_(2+)hydrocarbons(e.g.,ethane and propane)beyond methane remains an open question.Here,we demonstrate the direct synthesis of ethane and propane via reactions between amorphous carbon and H_(2) under upper mantle conditions(2-10 GPa and 800-1200℃).A systematic investigation reveals that increasing structural disorder in carbon precursors,from graphite to glassy carbon-Ⅱ and carbon black,enhances the production of C_(2)-C_(3) hydrocarbons.Through integrated X-ray diffraction and reverse Monte Carlo simulations,we establish that the continuous random atomic network structures in amorphous carbon enable one-step synthesis of heavy hydrocarbons with H_(2).These models establish a direct link between atomic-scale carbon structures and the one-step synthesis of C_(2+) hydrocarbons under H_(2)-rich,high-pressure,and high-temperature conditions—potentially revealing an efficient mechanism for the abiotic production of C_(2+) hydrocarbons in the upper mantle.
基金supported by the Learning&Academic Research Institution for Master’s,PhD students,and Postdocs LAMP Program of the National Research Foundation of Korea(NRF)grant funded by the Ministry of Education(No.RS-2023-00301974)This work was also supported by the Glocal University 30 Project fund of Gyeongsang National University in 2025.
文摘Lithium manganese silicate(Li-Mn-Si-O)cathodes are key components of lithium-ion batteries,and their physical and mechanical properties are strongly influenced by their underlying crystal structures.In this study,a range of machine learning(ML)algorithms were developed and compared to predict the crystal systems of Li-Mn-Si-O cathode materials using density functional theory(DFT)data obtained from the Materials Project database.The dataset comprised 211 compositions characterized by key descriptors,including formation energy,energy above the hull,bandgap,atomic site number,density,and unit cell volume.These features were utilized to classify the materials into monoclinic(0)and triclinic(1)crystal systems.A comprehensive comparison of various classification algorithms including Decision Tree,Random Forest,XGBoost,Support VectorMachine,k-Nearest Neighbor,Stochastic Gradient Descent,Gaussian Naive Bayes,Gaussian Process,and Artificial Neural Network(ANN)was conducted.Among these,the optimized ANN architecture(6–14-14-14-1)exhibited the highest predictive performance,achieving an accuracy of 95.3%,aMatthews correlation coefficient(MCC)of 0.894,and an F-score of 0.963,demonstrating excellent consistency with DFT-predicted crystal structures.Meanwhile,RandomForest and Gaussian Processmodels also exhibited reliable and consistent predictive capability,indicating their potential as complementary approaches,particularly when data are limited or computational efficiency is required.This comparative framework provides valuable insights into model selection for crystal system classification in complex cathode materials.
基金supported by the Research Project on Strengthening the Construction of an Important Ecological Security Barrier in Northern China by Higher Education Institutions in the Inner Mongolia Autonomous Region(STAQZX202313)the Inner Mongolia Autonomous Region Education Science‘14th Five-Year Plan’2024 Annual Research Project(NGJGH2024635).
文摘Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled thermomechanical fields remains insufficiently understood.In this study,transmission and scanning electron microscopy were employed to observe dislocation structures and grain boundary heterogeneities in processed aluminum alloys,suggesting stress concentrations and microstructural inhomogeneities associated with vacancy accumulation.To complement these observations,first-principles calculations and molecular dynamics simulations were conducted for seven single-vacancy configurations in face-centered cubic aluminum.The stress response,total energy,density of states(DOS),and differential charge density were examined under varying compressive strain(ε=0–0.1)and temperature(0–600 K).The results indicate that face-centered vacancies tend to reduce mechanical strength and perturb electronic states near the Fermi level,whereas corner and edge vacancies appear to have weaker effects.Elevated temperatures may partially restore electronic uniformity through thermal excitation.Overall,these findings suggest that vacancy position exerts a critical but position-dependent influence on coupled structure-property relationships,offering theoretical insights and preliminary experimental support for defect-engineered aluminum alloy design.
基金supported by a project of the Tsinghua Shenzhen International Graduate School-Shenzhen Pengrui Young Faculty Program of Shenzhen Pengrui Foundation(Grant No.SZPR2023007)Natural Science Foundation of Sichuan Province(Grant No.2025ZNSFSC0449)Shenzhen Science and Technology Program(Grant No.RCBS20231211090637065).
文摘Lithium-ion batteries with LiCoO_(2)(LCO)cathodes are widely used in various electronic devices,resulting in a large amount of spent LCO(SLCO).Therefore,there is an urgent need for an efficient technique for recycling SLCO.However,due to the presence of cobalt oxide with a spinel phase on the surface of highly-degraded LCO,the strong electrostatic repulsion from the transition metal octahedron poses a high Li replenishment barrier,making the regeneration of highly-degraded LCO a challenge.Herein,we propose a structural transformation strategy for reconstructing Li replenishment channels to aid the direct regeneration of highly-degraded LCO.In this approach,ball milling is employed to disrupt the inherent structure of highly-degraded LCO,thereby releasing the internal stress and converting the surface spinel phase into a homogeneous amorphous structure,which promotes Li insertion and regeneration.The regenerated LCO(RLCO)exhibits an outstanding discharge capacity of 179.10 mAh·g^(−1) in the voltage range of 3.0–4.5 V at 0.5 C.The proposed strategy is an effective regeneration approach for highly-degraded LCO,thereby facilitating the efficient recycling of spent lithium-ion battery cathode materials.
文摘Noble metal-based intermetallic compounds(IMCs)with ordered atomic arrangements exhibit remarkable electrocatalytic activity owing to their unique crystal and electronic structures.During the past years,great advance has been made in the development of noble metal-based IMCs.Recently,Lu and coworkers reported ultrathin“amorphous/intermetallic”(A/IMC)heterophase PtPbBi nanosheets(NSs)with a thickness of 2.5±0.3 nm.The oxidative etching effect caused by the coexistence of O_(2)and Br^(-)ions plays a crucial role in the formation of the IMC and unique two-dimensional structure with irregular shapes and curled edges.This study shows that fabricating an A/IMC heterophase structure with a multimetallic composition can effectively enhance the catalytic performances of noble metal-based electrocatalysts.
基金Project supported by the National Science Foundation for 0utstanding Young Scientists of China （Grant No 50125101）.
文摘Pr-based bulk metallic amorphous （BMA） rods （Pr60Ni30Al10） and Al-based amorphous ribbons （Al87Ni10Pr3） have been prepared by using copper mould casting and single roller melt-spun techniques, respectively. Thermal parameters deduced from differential scanning calorimeter （DSC） indicate that the glass-forming ability （GFA） of Pr60Ni30Al10 BMA rod is far higher than that of Al87Ni10Pr3 ribbon. A comparative study about the differences in structure between the two kinds of glass-forming alloys, superheated viscosity and crystallization are also made. Compared with the amorphous alloy Al87Ni10Pr3, the BMA alloy Pr60Ni30Al10 shows high thermal stability and large viscosity, small diffusivity at the same superheated temperatures. The results of x-Ray diffraction （XRD） and transmission electron microscope （TEM） show the pronounced difference in structure between the two amorphous alloys. Together with crystallization results, the main structure compositions of the amorphous samples are confirmed. It seems that the higher the GFA, the more topological type clusters in the Pr-Ni-Al amorphous alloys, the GFAs of the present glass-forming alloys are closely related to their structures.
基金supported by the National Natural Science Foundation of China(No.51571148)the National Key Research and Development Program of China(No.2017YFE0302600).
文摘The effect of structural order in the parent alloy substrate on the oxidation kinetics and oxide phase evolution was investigated for the thermal oxidation of amorphous Cu33at.%Zr67at.%and crystalline CuZr2 alloys of identical compositions in the temperature range of 200–250?C.It was found that,besides the strong preferential oxidation of Zr in both alloys,the lack of structural order in the amorphous Cu33at.%Zr67at.%alloy results in much slower oxidation kinetics,as well as in distinctly different microstructures of the oxide overgrowth and its Zr-depletion zone in the wake of the ZrO2 overlayer growth front.The experimental findings can be rationalized on the basis of the strikingly different atomic mobilities of Cu,Zr and dissolved O in the amorphous and crystalline alloys,which also results in different nucleation barriers for crystalline oxide nucleation.The thus obtained knowledge on the underlying oxidation mechanisms provides new and profound insights into the surface engineering of metallic alloys.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.51871039,51571047,and 51771039)the Fundamental Research Funds for the Central Universities(DUT17ZD212).
文摘The formation,thermal stability,crystallized structure,and magnetic properties of melt-spun Co80-xSmxB20(x=0–20)amorphous alloys have been investigated.A single amorphous phase is formed for the alloys with x=0–15.The first crystallization temperature gradually increases from 670 to 955 K as x increases from 0 to 10,and decreases to 836K when x=15.After optimum annealing,the nanocomposite structure consisting of SmCo12B6+fcc-Co+Sm2Co17 phases is formed for the alloys with x=5 and 7.5,and SmCo12B6+Sm2Co17+SmCo3,SmCo12B6+Sm2Co17+SmCo4B,and SmCo12B6+SmCo4B phases are formed for the alloys with x=10,12.5,and 15,respectively.The coercivity of the annealed alloys increases remarkably from 103.5 to 1249.4 kA m^-1 as x increases from 5 to 15,while the magnetization at the applied field of 2.0T decreases from 0.51 to 0.16T.The improved magnetic hardness with rising Sm content is attributed to the formation of the hard magnetic phases with higher magnetocrystalline anisotropy and the increase in their volume fraction.
基金Project supported by Foundation for Innovative Research Groups of ChinaProject(50634060) supported by the National Natural Science Founation of China
文摘Zirconia-mullite nano-composite ceramics were fabricated by in-situ controlled crystallization of Si-Al-Zr-O amorphous bulk, which were first treated at 900-1000 ℃ for nucleation, then treated at higher temperature for crystallization to obtain ultra-fine zirconia-mullite composite ceramics. The effects of treating temperature and ZrO2 addition on mechanical properties and microstructure were analyzed. A unique structure in which there are a lot of near equiaxed t-ZrO2 grains and fine yield-cracks has been developed in the samples with 15% zirconia addition treated at 1 150 ℃ . This specific microstructure is much more effective in toughening ceramics matrix and results in the best mechanical properties. The flexural strength and fracture toughness are 520 MPa and 5.13 MPa·m1/2, respectively. Either higher zirconia addition or higher crystallization temperature will produce large size rod-like ZrO2 and mullite grains, which are of negative effect on mechanical properties of this new composite ceramics.
文摘The amorphous and crystal structures of Zr 41 Ti 14 Ni 10 Cu 12.5 Be 22.5 alloy have been analyzed with X ray diffractometer. The structures of bulk amorphous Zr 41 Ti 14 Ni 10 Cu 12.5 B 22.5 alloy in solid, supercooled liquid and liquid states are almost of the same structure. The RDFs (Radius Distribution Function), the first coordination number, the first coordination radius, the correlation radius and atom number of the cluster were calculated for bulk amorphous Zr 41 Ti 14 Ni 10 Cu 12.5 B 22.5 alloy in different states. The first coordination sphere radii and the first coordination numbers are 0.312?nm, 11.2 in solid state, 0.301?nm, 10.932 in supercooled liquid region and 0.305?nm, 11.296 in liquid state. The crystal structure of Zr 41 Ti 14 Ni 10 Cu 12.5 B 22.5 alloy is consisted of several intermetallic compounds which are CuZr 2, Be 2Zr, etc. The reason of formation glass for this alloy is that there is a larger resistance for atoms to rearrange and form intermetallic compounds in a long range order.
基金Supported by the Key Subject of Huangshan University (No. 2010xkjq018)
文摘A novel NiII complex [{Ni（IBG）（4,4＇-bipy）（H2O）2}·3H2O]n 1 （H2IBG = isophthaloylbisglycine and 4,4＇-bipy = 4,4＇-bipyridine） has been synthesized and characterized by singlecrystal X-ray diffraction, elemental analysis, IR spectra and thermogravimetric analysis. It crystallizes in monoclinic, space group P2/c with a = 15.5420（7）, b = 22.4344（1）, c = 8.3455（5）, β = 101.538（3）o, V = 2670.1（7）3, Z = 4, C22H32N4NiO13, Mr = 619.23, Dc = 1.443 g/cm3, F（000） = 1296.0, μ（MoKα） = 0.750 mm-1, the final R = 0.0570 and wR = 0.1445 for 2296 observed reflections with I 〉 2σ（I）. In the structure, the NiII metal center is coordinated in an octahedral environment arranged by two water molecules, two carboxylate oxygen atoms and two nitrogen atoms from two 4,4＇-bipy ligands. Thermal decomposition and powder X-ray diffraction results indicate that the transformation from the crystal form, [{Ni（IBG）（4,4＇-bipy）（H2O）2}·3H2O]n, to the amorphous powder, Ni（IBG）（4,4＇-bipy）（H2O）2, is reversible, so the latter form may be utilized as an absorbing agent for water and water vapor.
基金supported by the National Natural Science Foundation of China (No. 51171122)the Sichuan Province Science and Technology Support Program (Nos. 2014GZ0090 and 2016GZ0262)
文摘Anisotropic magnets were obtained by hot deformation with the partial crystallized precursor prepared via spark-plasma sintering （SPS）. Amorphous powders with the nominal composition of Nd_28.72Fe_balCo_5.66 Ga_0.59B_0.92 （wt%） were used as the starting material. The results show that the amorphous powders would suffer varying degrees of crystallization even below the crystal- lization point during the SPS process under high pressure. And the pre-crystallized grains in precursors have great impacts on the microstructure and magnetic properties of the hot-deformed magnets. The final obtained anisotropic magnets exhibit homogeneous microstructure consisting of well-aligned and platelet-shaped Nd_2Fe_14B grains without abnormal growth. It can be found that a reasonable pro- portion of pre-crystallized gains could promote the pref- erential orientation in the magnet, leading to the achievement of optimal magnetic properties among the magnets with identical composition and best magnetic performance is achieved in the magnet hot deformed from the 490 ℃ high-pressure hot-pressed precursor.
文摘Elemental powders of Al-24. 4 % Fe (mole fraction) alloy were mechanically-alloyed using a conventional type ball-milling. Not only Fe particles gradually disperse in Al matrix but also Al and Fe crystal grains are refined to the order of ten nanometers after ball-milling for 180 h. The am0rphization starts at the early stage of ball milling and proceeds gradually. Complete amorphization is confirmed by ball-milling for 720h. The amorphization of the Powders after ball-milled for 180 h can be promoted by heating up to 673 K,which suggests a possibility of producing amorphous material by appropriate ball-milling and subsequent heating.
文摘The mixture model of Al_(85)Y_4Nd_4Ni_7 alloy in which a partiallycrystallized amorphous alloy is regarded as a nanocornposite of an Al nanoparticle and a remainingamorphous matrix is presented. Its evolution in the process of crystallization has been investigatedby differential scanning calorimetry (DSC), X-ray diffraction (XRD), and transmission electronmicroscopy (TEM). Mainly amorphous structure with alpha-Al nanocrystals embedded in the amorphousmatrix has been revealed by melt spining the alloy. Crystallization is showed to occur in threestages: (1) crystallization of amorphous alloy and formation of AINiY, AINdNi and unknowncrystalline phases, (2) formation of Al_3 Y and Al_3Nd, and (3) formation of Al_3Ni.
基金Supported by the National Natural Science Foundation of China。
文摘The crystallization behaviour of amorphous Al_(85)Ni_(10)Y_(5) alloy under high pressure was investigated.Results showed that the amorphous state can be preserved when the alloy is treated under high pressure at temperature below 325℃,the polytropic crystallization takes place when the alloy is treated at 325〜520 ℃ and 3〜6GPa for 1 min;the crystallizing product is nanometer scale supersaturated fee-Al solid solution particles dispersed in amorphous matrix;under 1 GPa pressure amorphous allloy crystallizes in an eutectic way,the crystallizing products are fee-Al,Al_(3)Y,Al_(3)Ni,AlNiY equilibrium crystalline phases etc.High pressure appreciably changes the crystallization mode and the products,elevates the crystallizing temperature.
