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
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
Ambient-air,moisture-assisted annealing is widely used in fabricating perovskite solar cells(PSCs).However,the inherent sensitivity of perovskite intermediate-phase to moisture—due to fast and spontaneous intermolecu...Ambient-air,moisture-assisted annealing is widely used in fabricating perovskite solar cells(PSCs).However,the inherent sensitivity of perovskite intermediate-phase to moisture—due to fast and spontaneous intermolecular exchange reaction—requires strict control of ambient humidity and immediate thermal annealing treatment,raising manufacturing costs and causing fast nucleation of perovskite films.We report herein a self-buffered molecular migration strategy to slow down the intermolecular exchange reaction by introducing a n-butylammonium bromide shielding layer,which limits moisture diffusion into intermediate-phase film.This further endows the notably wide nucleation time and humidity windows for perovskite crystallization in ambient air.Consequently,the optimized 1.68 e V-bandgap n-i-p structured PSC reaches a record-high reverse-scan(RS)PCE of 22.09%.Furthermore,the versatility and applicability of as-proposed self-buffered molecular migration strategy are certified by employing various shielding materials and 1.53 eV-/1.77 eV-bandgap perovskite materials.The n-i-p structured PSCs based on 1.53 eV-and 1.77 eV-bandgap perovskite films achieve outstanding RS PCEs of 25.23%and 19.09%,respectively,both of which are beyond of the state-of-the-art ambient-air processed PSCs.展开更多
The design of customized crystal plane heterojunction can effectively leverage the optimal anisotropic interaction of crystal plane,thereby enhancing photocatalytic activity.In this study,Co_(3)O_(4) exposed(111),(110...The design of customized crystal plane heterojunction can effectively leverage the optimal anisotropic interaction of crystal plane,thereby enhancing photocatalytic activity.In this study,Co_(3)O_(4) exposed(111),(110),and(100)crystal planes(designated as HCO,NCO,and CCO,respectively)were synthesized and successfully coupled with Cd_(0.5)Zn_(0.5)S(CZS).Among these composites,the HCO/CZS exhibited best hydrogen evolution activity.In conjunction with DFT calculations and femtosecond transient absorption spectroscopy,it has been found that:the crystal plane interaction between HCO and CZS enabled the composite catalyst to exhibit optimal anisotropy in crystal plane carrier transport,crystal plane active sites,and crystal plane electronic structure.This interaction induces a redistribution of electrons at their contact interface,thereby establishing a built-in electric field that facilitates the formation of ohmic heterojunction between HCO and CZS.The synergistic effect of the ohmic heterojunction and crystal plane anisotropy not only decreases the Gibbs free energy of hydrogen adsorption but also facilitates the efficient spatial separation and rapid transfer of electron-hole pairs.This study offers valuable insights into the customization of crystal plane heterojunctions,aiming to maximize anisotropic interactions between crystal planes in order to enhance photocatalytic hydrogen evolution.展开更多
Machine learning has revolutionized many fields,including materials science.However,predicting the properties of crystalline materials using machine learning faces challenges in input encoding,output versatility,and i...Machine learning has revolutionized many fields,including materials science.However,predicting the properties of crystalline materials using machine learning faces challenges in input encoding,output versatility,and interpretability.We introduce Crystal BERT,an adaptable transformer-based framework integrating space group,elemental,and unit cell information.This novel structure can seamlessly combine diverse features and accurately predict various physical properties,including topological properties,superconducting transition temperatures,dielectric constants,and more.Crystal BERT provides insightful interpretations of features influencing target properties.Our results indicate that space group and elemental information are crucial for predicting topological and superconducting properties,underscoring their intricate nature.By incorporating these features,we achieve91%accuracy in topological classification,surpassing prior studies and identifying previously misclassified materials.This research demonstrates that integrating diverse material information enhances the prediction of complex material properties,paving the way for more accurate and interpretable machine learning models in materials science.展开更多
Traditional desorption methods in porous sorbents rely heavily on energy-intensive processes such as heating,vacuum pumping,or inert gas purging[1].While effective,these approaches incur substantial energy and operati...Traditional desorption methods in porous sorbents rely heavily on energy-intensive processes such as heating,vacuum pumping,or inert gas purging[1].While effective,these approaches incur substantial energy and operational costs,particularly for hydrocarbons with high boiling points or strong host-vip interactions[2].This is the same case in the newly-developed macrocyclebased crystalline adsorbents,namely nonporous adaptive crystals(NACs).To address these challenges,a recent study published in Angewandte Chemie International Edition by Jie,Ma,and co-workers reported an innovative molecular-"squeeze"triggered desorption mechanism in NACs[3-5].Specifically,ethyl acetate(EA)triggers vip desorption without penetrating the crystal pores or voids.Instead,EA molecules interact with the crystal surface through supramolecular forces,causing the adaptive closure of voids and the subsequent release of vip molecules.Unlike conventional sponges that rely on mechanical squeeze to deform themselves in the bulk for vip release,these macrocycle crystals undergo structural deformation at the molecular level and condensed phase when exposed to vaporized molecules.Because of the similar behavior between sponges and such NACs,the authors name them as sponge-likemacrocyclecrystals.展开更多
In this paper,a terahertz slotted waveguide array antenna is designed based on photonic crystal,which can realize efficient radiation of terahertz waves.The electromagnetic wave is fed from the rectangular waveguide a...In this paper,a terahertz slotted waveguide array antenna is designed based on photonic crystal,which can realize efficient radiation of terahertz waves.The electromagnetic wave is fed from the rectangular waveguide at the bottom of the antenna,coupled to photonic crystal waveguide through photonic crystal cavity,and radiated outward through slots at the top layer of antenna.The simulation results show that the antenna achieves a peak gain of 13.45 dBi at 360 GHz,a half-power beam width of 10.9°,and a side lobe level of−13.9 dB.The antenna based on photonic crystal has the advantages of low profile,low loss,and high radiation efficiency,which can be applied to terahertz wireless communication systems.展开更多
The samples of single crystal superalloy DD6 are grit blasted and then heat treated either with the standard heat treatment procedure or in the temperature range of 1 000-1 250 ℃ for 4-16 h at vacuum atmosphere, then...The samples of single crystal superalloy DD6 are grit blasted and then heat treated either with the standard heat treatment procedure or in the temperature range of 1 000-1 250 ℃ for 4-16 h at vacuum atmosphere, then the recrystallization behavior of DD6 alloy is investigated. The results show that the equiaxed recrystallization grains form in the 7 phase region where the as-cast γ＇ phases have been dissolved completely, and cellular recrystallization forms in the region where the ascast γ＇ phases have been dissolved partially. The cellular recrystallization area consists of cellular grains, and the cellular grain consists of cubic γ＇ phase, lamellar γ＇ phase and γ＋γ＇. The coexistence of the equiaxed recrystallization zones and cellular recrystallization zones is a re- crystallized characteristic of the cold worked single crystal samples which are heat treated at a temperature lower than the solu- tion temperature. When the heating temperature is higher than 1 150 ℃, with the increase of heat treating temperature, the equiaxed recrystallization zone expands, whereas the cellular recrystallization zone shrinks. All the deformed regions are consumed by equiaxed recrystallization after annealing at solution temperature.展开更多
In contrast to research on active sites in nanomaterials,lithium tantalate single crystals,known for their exceptional optical properties and long-range ordered lattice structure,present a promising avenue for in-dept...In contrast to research on active sites in nanomaterials,lithium tantalate single crystals,known for their exceptional optical properties and long-range ordered lattice structure,present a promising avenue for in-depth exploration of photocatalytic reaction systems with fewer constraints imposed by surface chemistry.Typically,the isotropy of a specific facet provides a perfect support for studying heteroatom doping.Herein,this work delves into the intrinsic catalytic sites for photocatalytic nitrogen fixation in iron-doped lithium tantalate single crystals.The presence of iron not only modifies the electronic structure of lithium tantalate,improving its light absorption capacity,but also functions as an active site for the nitrogen adsorption and activation.The photocatalytic ammonia production rate of the iron-doped lithium tantalate in pure water is maximum 26.95μg cm^(−2)h^(−1),which is three times higher than that of undoped lithium tantalate.The combination of first-principles simulations with in situ characterizations confirms that iron doping promotes the rate-determining step and changes the pathway of hydrogenation to associative alternating.This study provides a new perspective on in-depth investigation of intrinsic catalytic active sites in photocatalysis and other catalytic processes.展开更多
随着量子计算技术的不断发展,依赖传统公钥密码体制三大功能(密钥协商/数字签名/公钥加密)的各种应用系统将不再安全.为应对量子威胁,以美国国家标准与技术研究院(National Institute of Standards and Technology,NIST)为首的国际标准...随着量子计算技术的不断发展,依赖传统公钥密码体制三大功能(密钥协商/数字签名/公钥加密)的各种应用系统将不再安全.为应对量子威胁,以美国国家标准与技术研究院(National Institute of Standards and Technology,NIST)为首的国际标准组织积极征集与部署后量子密码(Post Quantum Cryptography,PQC)算法的标准化工作,致力于在真正实用型量子计算机问世之前,提前完成传统公钥密码算法到PQC算法的迁移过渡.Crystals-Dilithium是NIST-PQC标准中的一种基于格的数字签名算法,其安全性高,运算速度快,是实现抵抗量子攻击数字签名算法的重要路径之一.本文从主流Crystals-Dilithium数字签名算法的理论基础出发,从底层关键组件的优化方法和整体硬件构架设计方法着手,围绕硬件资源优化和性能优化等现有方法和成果对比展开分析介绍,为研究者们后续研究探明方向,希望为设计性能与硬件资源均衡的后量子数字签名密码芯片提供有力参考.展开更多
Machine learning(ML)can optimize the research paradigm and shorten the time from discovery to application of novel functional materials,pharmaceuticals,and fine chemicals.Besides supporting material and drug design,ML...Machine learning(ML)can optimize the research paradigm and shorten the time from discovery to application of novel functional materials,pharmaceuticals,and fine chemicals.Besides supporting material and drug design,ML is a potentially valuable tool for predictive modeling and process optimization.Herein,we first review the recent progress in data-driven ML for molecular crystal design,including property and structure predictions.ML can accelerate the development of the solvates,co-crystals,and colloidal nanocrystals,and improve the efficiency of crystal design.Next,this review summarizes ML algorithms for crystallization behavior prediction and process regulation.ML models support drug solubility prediction,particle agglomeration prediction,and spherical crystal design.ML-based in situ image processing can extract particle information and recognize crystal products.The application scenarios of ML algorithms utilized in crystallization processes and two control strategies based on supersaturation regulation and image processing are also presented.Finally,emerging techniques and the outlook of ML in drug molecular design and industrial crystallization processes are outlined.展开更多
This paper reports the efficiency of the solvent-driven fractional crystallization(SDFC)process using ethanol,also known as antisolvent crystallization,in the treatment of a concentrated wastewater by reverse osmosis(...This paper reports the efficiency of the solvent-driven fractional crystallization(SDFC)process using ethanol,also known as antisolvent crystallization,in the treatment of a concentrated wastewater by reverse osmosis(RO).This experiment evaluated the effects of varying the volumetric mixing ratio of ethanol-to-RO concentrate,in conjunction with the incorporation of Ca(OH)_(2),on the efficiency of magnesium and boron removal.The incorporation of Ca(OH)_(2)resulted in an enhancement of the reduction of magnesium and boron concentrations at a mixing ratio of 85:15(v/v)and a pH of 12.In these conditions,the removal efficiencies achieved for magnesium and boron were 98.64%and 90.82%,respectively.The findings indicate that Ca(OH)_(2)has a significant impact on enhancing the removal efficiencies of these elements.The RO concentrated wastewater used in this experiment exhibited a salinity of 50,497.200 ppm prior to the SDFC test.The experimental results also showed a 48.10%reduction in salinity and 28.10%salt precipitation at the maximum mixing ratio and pH level examined.The tested process demonstrated significant reduction of scaling ions including calcium,magnesium,and sulfate.Similar behavior was observed for arsenic and manganese.Moderate removal efficiencies were observed for monovalent ions such as chloride,sodium,and potassium.However,the process was no effective for iron and lithium,which showed low removal efficiencies.Based on the results obtained,SDFC technology is seen as a promising technological option for application in the treatment of complex mining wastewaters.展开更多
For emerging renewable and sustainable energy technologies,single crystal materials have become key materials to enhance electrocatalytic performance because of their atomic-level ordered structures and tailorable sur...For emerging renewable and sustainable energy technologies,single crystal materials have become key materials to enhance electrocatalytic performance because of their atomic-level ordered structures and tailorable surface and interfacial properties.Various single crystal types,including metals,semiconductors,ceramics,organics,and nanocrystals,exhibit superior catalytic selectivity and stability in reactions such as water splitting and carbon/nitrogen cycles,benefiting from high electrical conductivity,tunable energy bands,and active sites with high surface energy.Through surface modification,interfacial atomic doping,and heterostructure construction,the distribution of active sites,electronic structure,and mass transport can be precisely regulated,significantly optimizing the catalytic kinetics of single crystal materials.In situ characterizations elucidate catalytic mechanisms at the atomic scale,while emerging methods like AI-assisted synthesis and bio-template directed growth offer pathways to overcome bottlenecks in the precision and cost of single crystal preparation.In addressing stability challenges in complex environments,strategies such as organic-inorganic hybridization and gradient interface design effectively mitigate interfacial instability.Future research should focus on cross-scale structural regulation and multidisciplinary integration to facilitate the transition of single crystal electrocatalysts from fundamental research to industrial applications,enabling efficient energy conversion.展开更多
We demonstrate the growth,thermal,spectroscopy and laser performance of an Er3+doped Gdo.iYo.9AlO3(Er:GYAP)disorder crystal grown by Czochralski method.The crystal with space group Pbnm and lattice parameters of a=0.5...We demonstrate the growth,thermal,spectroscopy and laser performance of an Er3+doped Gdo.iYo.9AlO3(Er:GYAP)disorder crystal grown by Czochralski method.The crystal with space group Pbnm and lattice parameters of a=0.5185 nm,b=0.5327 nm,c=0.7378 nm,α=β=90°and V=0.203784 nm3 are obtained by fitting powder X-ray diffraction data.The Mohr's hardnesses along three axes are 6.94,7.27,and 7.44.The thermal expansion coefficient of b axis is 4.20×10^(-6)k^(-1)and the density is 5.88 g/cm3.The thermal conductivities are characterized as K_(a)=6.24,K_(b)=5.57,and K_(c)=6.83 W/(m·K).Meanwhile,the refractive index,absorption and emission spectra in triaxial di-rections are determined.Besides,level lifetimes of 4l11/2 and 413/2 are 0.86 and 2.83 ms.Finally,the~2.7μm multiwavelength laser outputs are observed with maximum average power of 628 mW and beam quality factors M_(x)^(2)/M_(y)^(2) of 1.42/1.45.The results prove that the Er:GYAP crystal is a promising gain medium for generating mid-infrared lasers.展开更多
Photonic crystal surface emitting lasers(PCSELs)utilize the Bragg diffraction of two-dimensional photonic crystals to achieve a single-mode output with a high power and a small divergence angle,and has recently attrac...Photonic crystal surface emitting lasers(PCSELs)utilize the Bragg diffraction of two-dimensional photonic crystals to achieve a single-mode output with a high power and a small divergence angle,and has recently attracted much attention^([1−3]).In 2023,Kyoto University reported GaAs-based 945 nm PCSELs with a continuous-wave(CW)single-mode output power of exceeding 50 W,and a narrow beam divergence angle of 0.05°,demonstrating a brightness of 1 GW·cm^(−2)·sr^(−1),which rivals those of the existing bulky lasers^([4]).展开更多
In this study,a batch of φ12 mm Cs_(2)LiYCl_(6):Ce crystals codoped with different contents of Cu^(+)and Sc^(3+)was successfully grown using the Multi-ampule Bridgeman method.A new emission peaking at 418 nm is found...In this study,a batch of φ12 mm Cs_(2)LiYCl_(6):Ce crystals codoped with different contents of Cu^(+)and Sc^(3+)was successfully grown using the Multi-ampule Bridgeman method.A new emission peaking at 418 nm is found in the photoluminescence spectra of CLYC:Ce codoped with Cu^(+)ion.Codoping Cu^(+)or Sc^(3+)both increases the proportion of intrinsic self-trapped exciton(STE)luminescence,and extends the excitation band of Ce^(3+),especially in Cu^(+)codoped samples,where a new absorption peak at 248 nm can be identified.The light yield of Cu^(+)codoped samples remains largely unchanged,but the energy resolution shows a slight deterioration.Both light yield and energy resolution degrade after Sc^(3+)codoping,and the effect is much severe than that of Cu^(+)codoped samples.X-ray induced afterglow can be suppressed after Cu^(+)codoping and low content of Sc^(3+)codoping.The scintillation decay variation also depends on the codoping ions and their contents.展开更多
Reaction crystallization method is a common cocrystal synthesis approach attributed to the advantage of avoiding individual crystallization of insoluble components,but faces the defects of soluble components precipita...Reaction crystallization method is a common cocrystal synthesis approach attributed to the advantage of avoiding individual crystallization of insoluble components,but faces the defects of soluble components precipitated due to organic solvent volatilization and the formation of unwanted solvates.Our group recently proposed a slurry method based on deep eutectic solvents(DESs)for cocrystal synthesis,which is green,safe and can avoid solvate formation.However,some reactions only produce insoluble raw materials rather than cocrystals due to insufficient activity of the soluble cocrystal co-formers in DESs.Herein,combining the dual benefits of the two methods,a novel reaction crystallization method based on DESs was proposed and employed for cocrystal synthesis of nicotinamide,carbamazepine and theophylline,which can prevent individual crystallization,unwanted solvate formation,and soluble component precipitation,providing a promising alternative for green and efficient synthesis of cocrystals.展开更多
Mg_(x)(Ni_(0.8)La_(0.2))_(100-x),where x=60,70,80,exhibiting a nanocrystalline microstructure,were prepared through the crystallization of amorphous alloys.The investigation encompassed the phase constitution,grain si...Mg_(x)(Ni_(0.8)La_(0.2))_(100-x),where x=60,70,80,exhibiting a nanocrystalline microstructure,were prepared through the crystallization of amorphous alloys.The investigation encompassed the phase constitution,grain size,microstructural stability,and hydrogen storage properties.Crystallization kinetics,along with in-situ high-energy XRD characterization,revealed a concentrated and synchronous crystallization of Mg_(2)Ni and RE-Mg-Ni ternary phases with the increase in La and Ni content.The attributed synchronous crystallization process was found to be a result of the close local affinity of Mg_(2)Ni and RE-Mg-Ni ternary phases,as assessed by the thermodynamic Miedema model.Significant secondary phase pinning effect,arising from the high likelihood of well-matching phase structures between Mg_(2)Ni,LaMg_(2)Ni,and LaMgNi_(4),was validated through both the edge-to-edge matching model prediction and experimental observation.Thefine and homogeneous microstructure was shown to be a consequence of fast crystallization kinetics and the secondary phase pinning effect.Improved activation performance and cycling stability were observed,stemming from grain refinement and excellent microstructural stability.Our study provides insights into mechanism of grain refinement of nanocrystalline microstructure tailored by phase constitution and crystallization kinetics in the amorphous-crystallization route.We also demonstrate the potential of material design guided by phase equilibria and crystallographic predictions to improve nanocrystalline with excellent microstructural stability.展开更多
Poly(L-lactic acid)(PLLA)has been widely concerned because of its excellent biodegradability and biocompatibility.However,the poor crystallization ability of PLLA during the molding process not only leads to weak mech...Poly(L-lactic acid)(PLLA)has been widely concerned because of its excellent biodegradability and biocompatibility.However,the poor crystallization ability of PLLA during the molding process not only leads to weak mechanical properties but also reduces the processing efficiency,which limits the application of PLLA greatly.Enhancing crystallization ability of PLLA via introducing inorganic nanoparticles usually sacrifices biodegradability or transparency.Here,the microfine fibers with stereocomplex(SC)crystallites were incorporated into PLLA film to tailor the crystallization ability of PLLA as well as the mechanical properties.The results confirmed that the crystallization ability of PLLA matrix under different circumstances could be greatly enhanced by a few amounts of SC crystalline fibers,and synchronously enhanced tensile strength and ductility were also achieved,especially at relatively high temperature.Due to the relatively homogeneous dispersion of SC crystalline fibers and the similar refractive index between components,the PLLA-based film also exhibited high transparency,up to 85%-90%depending on the content of SC crystalline fibers.This work provides guidance for manufacturing transparent PLLA-based packaging materials with good crystallization capability and mechanical properties.展开更多
Corresponding to the continuous dynamic recrystallization mechanism,we proposed a dislocation entanglement model and an energy-based criterion to capture the formation of subgrain boundaries during high strain rate de...Corresponding to the continuous dynamic recrystallization mechanism,we proposed a dislocation entanglement model and an energy-based criterion to capture the formation of subgrain boundaries during high strain rate deformation.A physical relationship between grain refinement and dislocation evolution is established and incorporated into the crystal plasticity constitutive model,where the spatial position of the subgrain boundaries can be determined by the energy minimization path.The developed constitutive model is implemented to simulate the dynamic compression and tension tests of pure copper by the crystal plasticity finite element method.Results show that the developed grain refinement model based on the dislocation entanglement gives good agreement with the experimental data validating its feasibility and rationality.The strengthening effect of grain refinement on the flow stress of metals at high strain rates depends on the competition between the strengthening of grain boundary and the softening of dislocation consumption during grain refinement.Further,a series of dynamic compressions are performed on copper samples with different grain sizes to explore the strengthening effect of grain refinement.The corresponding mechanisms of strengthening are analyzed and their respective contributions are also discussed in detail.The developed model can accurately predict the grain refinement of metals and capture its effect on strain hardening under high strain rate deformation.展开更多
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.
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the financial support from the National Key R&D Program of China(2021YFF0500500)the National Natural Science Foundation of China(62474131,62274132,and 62204189)。
文摘Ambient-air,moisture-assisted annealing is widely used in fabricating perovskite solar cells(PSCs).However,the inherent sensitivity of perovskite intermediate-phase to moisture—due to fast and spontaneous intermolecular exchange reaction—requires strict control of ambient humidity and immediate thermal annealing treatment,raising manufacturing costs and causing fast nucleation of perovskite films.We report herein a self-buffered molecular migration strategy to slow down the intermolecular exchange reaction by introducing a n-butylammonium bromide shielding layer,which limits moisture diffusion into intermediate-phase film.This further endows the notably wide nucleation time and humidity windows for perovskite crystallization in ambient air.Consequently,the optimized 1.68 e V-bandgap n-i-p structured PSC reaches a record-high reverse-scan(RS)PCE of 22.09%.Furthermore,the versatility and applicability of as-proposed self-buffered molecular migration strategy are certified by employing various shielding materials and 1.53 eV-/1.77 eV-bandgap perovskite materials.The n-i-p structured PSCs based on 1.53 eV-and 1.77 eV-bandgap perovskite films achieve outstanding RS PCEs of 25.23%and 19.09%,respectively,both of which are beyond of the state-of-the-art ambient-air processed PSCs.
文摘The design of customized crystal plane heterojunction can effectively leverage the optimal anisotropic interaction of crystal plane,thereby enhancing photocatalytic activity.In this study,Co_(3)O_(4) exposed(111),(110),and(100)crystal planes(designated as HCO,NCO,and CCO,respectively)were synthesized and successfully coupled with Cd_(0.5)Zn_(0.5)S(CZS).Among these composites,the HCO/CZS exhibited best hydrogen evolution activity.In conjunction with DFT calculations and femtosecond transient absorption spectroscopy,it has been found that:the crystal plane interaction between HCO and CZS enabled the composite catalyst to exhibit optimal anisotropy in crystal plane carrier transport,crystal plane active sites,and crystal plane electronic structure.This interaction induces a redistribution of electrons at their contact interface,thereby establishing a built-in electric field that facilitates the formation of ohmic heterojunction between HCO and CZS.The synergistic effect of the ohmic heterojunction and crystal plane anisotropy not only decreases the Gibbs free energy of hydrogen adsorption but also facilitates the efficient spatial separation and rapid transfer of electron-hole pairs.This study offers valuable insights into the customization of crystal plane heterojunctions,aiming to maximize anisotropic interactions between crystal planes in order to enhance photocatalytic hydrogen evolution.
基金supported by the Natural Science Foundation of China(Grant Nos.12350404 and 12174066)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302600)+2 种基金the Science and Technology Commission of Shanghai Municipality(Grant Nos.23JC1400600,24LZ1400100,and 2019SHZDZX01)sponsored by“Shuguang Program”supported by Shanghai Education Development FoundationShanghai Municipal Education Commission。
文摘Machine learning has revolutionized many fields,including materials science.However,predicting the properties of crystalline materials using machine learning faces challenges in input encoding,output versatility,and interpretability.We introduce Crystal BERT,an adaptable transformer-based framework integrating space group,elemental,and unit cell information.This novel structure can seamlessly combine diverse features and accurately predict various physical properties,including topological properties,superconducting transition temperatures,dielectric constants,and more.Crystal BERT provides insightful interpretations of features influencing target properties.Our results indicate that space group and elemental information are crucial for predicting topological and superconducting properties,underscoring their intricate nature.By incorporating these features,we achieve91%accuracy in topological classification,surpassing prior studies and identifying previously misclassified materials.This research demonstrates that integrating diverse material information enhances the prediction of complex material properties,paving the way for more accurate and interpretable machine learning models in materials science.
基金the Natural Science Foundation of Jiangsu Province(No.BK20240679)National Natural Science Foundation of China(No.22101134)are greatly acknowledged。
文摘Traditional desorption methods in porous sorbents rely heavily on energy-intensive processes such as heating,vacuum pumping,or inert gas purging[1].While effective,these approaches incur substantial energy and operational costs,particularly for hydrocarbons with high boiling points or strong host-vip interactions[2].This is the same case in the newly-developed macrocyclebased crystalline adsorbents,namely nonporous adaptive crystals(NACs).To address these challenges,a recent study published in Angewandte Chemie International Edition by Jie,Ma,and co-workers reported an innovative molecular-"squeeze"triggered desorption mechanism in NACs[3-5].Specifically,ethyl acetate(EA)triggers vip desorption without penetrating the crystal pores or voids.Instead,EA molecules interact with the crystal surface through supramolecular forces,causing the adaptive closure of voids and the subsequent release of vip molecules.Unlike conventional sponges that rely on mechanical squeeze to deform themselves in the bulk for vip release,these macrocycle crystals undergo structural deformation at the molecular level and condensed phase when exposed to vaporized molecules.Because of the similar behavior between sponges and such NACs,the authors name them as sponge-likemacrocyclecrystals.
基金supported by the National Natural Science Foundation of China(No.62375031)the Basic Research Project of Chongqing Science and Technology Commission(No.CSTC-2021jcyj-bsh0194)the Science and Technology Research Program of Chongqing Municipal Education Commission(No.KJQN202200602)。
文摘In this paper,a terahertz slotted waveguide array antenna is designed based on photonic crystal,which can realize efficient radiation of terahertz waves.The electromagnetic wave is fed from the rectangular waveguide at the bottom of the antenna,coupled to photonic crystal waveguide through photonic crystal cavity,and radiated outward through slots at the top layer of antenna.The simulation results show that the antenna achieves a peak gain of 13.45 dBi at 360 GHz,a half-power beam width of 10.9°,and a side lobe level of−13.9 dB.The antenna based on photonic crystal has the advantages of low profile,low loss,and high radiation efficiency,which can be applied to terahertz wireless communication systems.
文摘The samples of single crystal superalloy DD6 are grit blasted and then heat treated either with the standard heat treatment procedure or in the temperature range of 1 000-1 250 ℃ for 4-16 h at vacuum atmosphere, then the recrystallization behavior of DD6 alloy is investigated. The results show that the equiaxed recrystallization grains form in the 7 phase region where the as-cast γ＇ phases have been dissolved completely, and cellular recrystallization forms in the region where the ascast γ＇ phases have been dissolved partially. The cellular recrystallization area consists of cellular grains, and the cellular grain consists of cubic γ＇ phase, lamellar γ＇ phase and γ＋γ＇. The coexistence of the equiaxed recrystallization zones and cellular recrystallization zones is a re- crystallized characteristic of the cold worked single crystal samples which are heat treated at a temperature lower than the solu- tion temperature. When the heating temperature is higher than 1 150 ℃, with the increase of heat treating temperature, the equiaxed recrystallization zone expands, whereas the cellular recrystallization zone shrinks. All the deformed regions are consumed by equiaxed recrystallization after annealing at solution temperature.
基金supported by Natural Science Foundation of Shandong Province(Nos.ZR2022YQ42,ZR2021JQ15,ZR2021QE011,ZR2021ZD20,2022GJJLJRC-01)Innovative Team Project of Jinan(No.2021GXRC019)the National Natural Science Foundation of China(Nos.52022037,52202366).
文摘In contrast to research on active sites in nanomaterials,lithium tantalate single crystals,known for their exceptional optical properties and long-range ordered lattice structure,present a promising avenue for in-depth exploration of photocatalytic reaction systems with fewer constraints imposed by surface chemistry.Typically,the isotropy of a specific facet provides a perfect support for studying heteroatom doping.Herein,this work delves into the intrinsic catalytic sites for photocatalytic nitrogen fixation in iron-doped lithium tantalate single crystals.The presence of iron not only modifies the electronic structure of lithium tantalate,improving its light absorption capacity,but also functions as an active site for the nitrogen adsorption and activation.The photocatalytic ammonia production rate of the iron-doped lithium tantalate in pure water is maximum 26.95μg cm^(−2)h^(−1),which is three times higher than that of undoped lithium tantalate.The combination of first-principles simulations with in situ characterizations confirms that iron doping promotes the rate-determining step and changes the pathway of hydrogenation to associative alternating.This study provides a new perspective on in-depth investigation of intrinsic catalytic active sites in photocatalysis and other catalytic processes.
文摘随着量子计算技术的不断发展,依赖传统公钥密码体制三大功能(密钥协商/数字签名/公钥加密)的各种应用系统将不再安全.为应对量子威胁,以美国国家标准与技术研究院(National Institute of Standards and Technology,NIST)为首的国际标准组织积极征集与部署后量子密码(Post Quantum Cryptography,PQC)算法的标准化工作,致力于在真正实用型量子计算机问世之前,提前完成传统公钥密码算法到PQC算法的迁移过渡.Crystals-Dilithium是NIST-PQC标准中的一种基于格的数字签名算法,其安全性高,运算速度快,是实现抵抗量子攻击数字签名算法的重要路径之一.本文从主流Crystals-Dilithium数字签名算法的理论基础出发,从底层关键组件的优化方法和整体硬件构架设计方法着手,围绕硬件资源优化和性能优化等现有方法和成果对比展开分析介绍,为研究者们后续研究探明方向,希望为设计性能与硬件资源均衡的后量子数字签名密码芯片提供有力参考.
基金financially supported by the National Natural Science Foundation of China(22008173,21938009,and 21676179)the Major Key Technology Project of ShandongProvincial Key Research and Development Program(2021CXGC010514)the support of the China Scholarship Council。
文摘Machine learning(ML)can optimize the research paradigm and shorten the time from discovery to application of novel functional materials,pharmaceuticals,and fine chemicals.Besides supporting material and drug design,ML is a potentially valuable tool for predictive modeling and process optimization.Herein,we first review the recent progress in data-driven ML for molecular crystal design,including property and structure predictions.ML can accelerate the development of the solvates,co-crystals,and colloidal nanocrystals,and improve the efficiency of crystal design.Next,this review summarizes ML algorithms for crystallization behavior prediction and process regulation.ML models support drug solubility prediction,particle agglomeration prediction,and spherical crystal design.ML-based in situ image processing can extract particle information and recognize crystal products.The application scenarios of ML algorithms utilized in crystallization processes and two control strategies based on supersaturation regulation and image processing are also presented.Finally,emerging techniques and the outlook of ML in drug molecular design and industrial crystallization processes are outlined.
文摘This paper reports the efficiency of the solvent-driven fractional crystallization(SDFC)process using ethanol,also known as antisolvent crystallization,in the treatment of a concentrated wastewater by reverse osmosis(RO).This experiment evaluated the effects of varying the volumetric mixing ratio of ethanol-to-RO concentrate,in conjunction with the incorporation of Ca(OH)_(2),on the efficiency of magnesium and boron removal.The incorporation of Ca(OH)_(2)resulted in an enhancement of the reduction of magnesium and boron concentrations at a mixing ratio of 85:15(v/v)and a pH of 12.In these conditions,the removal efficiencies achieved for magnesium and boron were 98.64%and 90.82%,respectively.The findings indicate that Ca(OH)_(2)has a significant impact on enhancing the removal efficiencies of these elements.The RO concentrated wastewater used in this experiment exhibited a salinity of 50,497.200 ppm prior to the SDFC test.The experimental results also showed a 48.10%reduction in salinity and 28.10%salt precipitation at the maximum mixing ratio and pH level examined.The tested process demonstrated significant reduction of scaling ions including calcium,magnesium,and sulfate.Similar behavior was observed for arsenic and manganese.Moderate removal efficiencies were observed for monovalent ions such as chloride,sodium,and potassium.However,the process was no effective for iron and lithium,which showed low removal efficiencies.Based on the results obtained,SDFC technology is seen as a promising technological option for application in the treatment of complex mining wastewaters.
基金supported by National Natural Science Foundation of China(No.52202366)Taishan Scholar Project of Shandong Province(tstp20240515,tsqn202312217)+1 种基金Natural Science Foundation of Shandong Province(China,No.2025HWYQ-050,ZR2021QE011,ZR2022QH072,ZR2021QE284)the King Abdullah University of Science and Technology,the Center of Excellence for Renewable Energy and Storage Technologies.
文摘For emerging renewable and sustainable energy technologies,single crystal materials have become key materials to enhance electrocatalytic performance because of their atomic-level ordered structures and tailorable surface and interfacial properties.Various single crystal types,including metals,semiconductors,ceramics,organics,and nanocrystals,exhibit superior catalytic selectivity and stability in reactions such as water splitting and carbon/nitrogen cycles,benefiting from high electrical conductivity,tunable energy bands,and active sites with high surface energy.Through surface modification,interfacial atomic doping,and heterostructure construction,the distribution of active sites,electronic structure,and mass transport can be precisely regulated,significantly optimizing the catalytic kinetics of single crystal materials.In situ characterizations elucidate catalytic mechanisms at the atomic scale,while emerging methods like AI-assisted synthesis and bio-template directed growth offer pathways to overcome bottlenecks in the precision and cost of single crystal preparation.In addressing stability challenges in complex environments,strategies such as organic-inorganic hybridization and gradient interface design effectively mitigate interfacial instability.Future research should focus on cross-scale structural regulation and multidisciplinary integration to facilitate the transition of single crystal electrocatalysts from fundamental research to industrial applications,enabling efficient energy conversion.
基金the National Natural Science Foundation of China(52102012)Natural Science Foundation of Anhui Province(2208085QF217)the Fundamental Research Funds for the Central Universities(WK5290000004)。
文摘We demonstrate the growth,thermal,spectroscopy and laser performance of an Er3+doped Gdo.iYo.9AlO3(Er:GYAP)disorder crystal grown by Czochralski method.The crystal with space group Pbnm and lattice parameters of a=0.5185 nm,b=0.5327 nm,c=0.7378 nm,α=β=90°and V=0.203784 nm3 are obtained by fitting powder X-ray diffraction data.The Mohr's hardnesses along three axes are 6.94,7.27,and 7.44.The thermal expansion coefficient of b axis is 4.20×10^(-6)k^(-1)and the density is 5.88 g/cm3.The thermal conductivities are characterized as K_(a)=6.24,K_(b)=5.57,and K_(c)=6.83 W/(m·K).Meanwhile,the refractive index,absorption and emission spectra in triaxial di-rections are determined.Besides,level lifetimes of 4l11/2 and 413/2 are 0.86 and 2.83 ms.Finally,the~2.7μm multiwavelength laser outputs are observed with maximum average power of 628 mW and beam quality factors M_(x)^(2)/M_(y)^(2) of 1.42/1.45.The results prove that the Er:GYAP crystal is a promising gain medium for generating mid-infrared lasers.
基金funded by National Key R&D Program of China(Grant Nos.2024YFB3612200,2023YFB3609601,2022YFB3604300,2022YFB2802801,2022YFB3604802)Natural Science Foundation of China(Grant Nos.U24A20300,62174174,62274177,62275263,62325406,62374172,62304242,62304240,62404241)+4 种基金Youth Innovation Promotion Association of CAS(Grant Nos.2022323 and 2022324)Key R&D Program of Jiangsu Province(Grant No.BE2023018-2)Basic Research Program of Jiangsu(Grant No.BK20240126)Suzhou Science and Technology Program(Grant Nos.SYC2022089,ZXL2024379,and ZXL2024376)Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2022A1515110482 and 2022A1515110004).
文摘Photonic crystal surface emitting lasers(PCSELs)utilize the Bragg diffraction of two-dimensional photonic crystals to achieve a single-mode output with a high power and a small divergence angle,and has recently attracted much attention^([1−3]).In 2023,Kyoto University reported GaAs-based 945 nm PCSELs with a continuous-wave(CW)single-mode output power of exceeding 50 W,and a narrow beam divergence angle of 0.05°,demonstrating a brightness of 1 GW·cm^(−2)·sr^(−1),which rivals those of the existing bulky lasers^([4]).
基金Project supported by the National Key Research and Development Program,China(2022YFB3503600)Manned Space Station Engineering Space Science and Applications Program(MSAP)(ZDBS-ZRKJZTLC011)+3 种基金National Natural Science Foundation of China,China(11975303,12211530561,12305211)Shanghai Municipal Natural Science Foundation,China(21TS1400100)CAS Cooperative Research Project(121631KYSB20210017)CAS Project for Young Scientist in Basic Research(YSBR-024)。
文摘In this study,a batch of φ12 mm Cs_(2)LiYCl_(6):Ce crystals codoped with different contents of Cu^(+)and Sc^(3+)was successfully grown using the Multi-ampule Bridgeman method.A new emission peaking at 418 nm is found in the photoluminescence spectra of CLYC:Ce codoped with Cu^(+)ion.Codoping Cu^(+)or Sc^(3+)both increases the proportion of intrinsic self-trapped exciton(STE)luminescence,and extends the excitation band of Ce^(3+),especially in Cu^(+)codoped samples,where a new absorption peak at 248 nm can be identified.The light yield of Cu^(+)codoped samples remains largely unchanged,but the energy resolution shows a slight deterioration.Both light yield and energy resolution degrade after Sc^(3+)codoping,and the effect is much severe than that of Cu^(+)codoped samples.X-ray induced afterglow can be suppressed after Cu^(+)codoping and low content of Sc^(3+)codoping.The scintillation decay variation also depends on the codoping ions and their contents.
基金financially supported by National Natural Science Foundation of China(Nos.22101204 and 22271220)the project grant from the Innovation and Strengthening Project of Guangdong Pharmaceutical University-Special Project of the Guangdong Education Commission(No.2020KZDZX1128)+1 种基金the Research Projects of the Chinese Medicine Council of Guangdong Province(No.20231209)the Key Laboratory of Tropical Medicinal Resource Chemistry of the Ministry of Education at Hainan Normal University(No.RDZH2023001)。
文摘Reaction crystallization method is a common cocrystal synthesis approach attributed to the advantage of avoiding individual crystallization of insoluble components,but faces the defects of soluble components precipitated due to organic solvent volatilization and the formation of unwanted solvates.Our group recently proposed a slurry method based on deep eutectic solvents(DESs)for cocrystal synthesis,which is green,safe and can avoid solvate formation.However,some reactions only produce insoluble raw materials rather than cocrystals due to insufficient activity of the soluble cocrystal co-formers in DESs.Herein,combining the dual benefits of the two methods,a novel reaction crystallization method based on DESs was proposed and employed for cocrystal synthesis of nicotinamide,carbamazepine and theophylline,which can prevent individual crystallization,unwanted solvate formation,and soluble component precipitation,providing a promising alternative for green and efficient synthesis of cocrystals.
基金supported by National Natural Science Foundation of China(51761034,51961032,51962028 and 52261041)Innovation Foundation of Inner Mongolia University of Science and Technology(2019YQL03)+2 种基金Major Science and Technology Project of Inner Mongolia(2021ZD0029)Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(NJYT23005,NJYT23007)Program for Innovative Research Team in Universities of Inner Mongolia Autonomous Region(NMGIRT2401).
文摘Mg_(x)(Ni_(0.8)La_(0.2))_(100-x),where x=60,70,80,exhibiting a nanocrystalline microstructure,were prepared through the crystallization of amorphous alloys.The investigation encompassed the phase constitution,grain size,microstructural stability,and hydrogen storage properties.Crystallization kinetics,along with in-situ high-energy XRD characterization,revealed a concentrated and synchronous crystallization of Mg_(2)Ni and RE-Mg-Ni ternary phases with the increase in La and Ni content.The attributed synchronous crystallization process was found to be a result of the close local affinity of Mg_(2)Ni and RE-Mg-Ni ternary phases,as assessed by the thermodynamic Miedema model.Significant secondary phase pinning effect,arising from the high likelihood of well-matching phase structures between Mg_(2)Ni,LaMg_(2)Ni,and LaMgNi_(4),was validated through both the edge-to-edge matching model prediction and experimental observation.Thefine and homogeneous microstructure was shown to be a consequence of fast crystallization kinetics and the secondary phase pinning effect.Improved activation performance and cycling stability were observed,stemming from grain refinement and excellent microstructural stability.Our study provides insights into mechanism of grain refinement of nanocrystalline microstructure tailored by phase constitution and crystallization kinetics in the amorphous-crystallization route.We also demonstrate the potential of material design guided by phase equilibria and crystallographic predictions to improve nanocrystalline with excellent microstructural stability.
基金supported by the Sichuan Science and Technology Program(No.2023ZHCG0050)the China Postdoctoral Science Foundation(No.2023M742883)+2 种基金the Science and Technology Innovation Fund for Basic Scientific Research Operating Expenses of Central Universities(No.2682023CX002)the New Interdisciplinary Cultivation Fund of SWJTU(No.2682022KJ040)SEM characterizations were supported by the Analytical and Testing Center of Southwest Jiaotong University。
文摘Poly(L-lactic acid)(PLLA)has been widely concerned because of its excellent biodegradability and biocompatibility.However,the poor crystallization ability of PLLA during the molding process not only leads to weak mechanical properties but also reduces the processing efficiency,which limits the application of PLLA greatly.Enhancing crystallization ability of PLLA via introducing inorganic nanoparticles usually sacrifices biodegradability or transparency.Here,the microfine fibers with stereocomplex(SC)crystallites were incorporated into PLLA film to tailor the crystallization ability of PLLA as well as the mechanical properties.The results confirmed that the crystallization ability of PLLA matrix under different circumstances could be greatly enhanced by a few amounts of SC crystalline fibers,and synchronously enhanced tensile strength and ductility were also achieved,especially at relatively high temperature.Due to the relatively homogeneous dispersion of SC crystalline fibers and the similar refractive index between components,the PLLA-based film also exhibited high transparency,up to 85%-90%depending on the content of SC crystalline fibers.This work provides guidance for manufacturing transparent PLLA-based packaging materials with good crystallization capability and mechanical properties.
基金the National Science Foundation of China(Grant No.12172144)the Fundamental Research Funds for Central Universities(Grant No.2016YXMS097)。
文摘Corresponding to the continuous dynamic recrystallization mechanism,we proposed a dislocation entanglement model and an energy-based criterion to capture the formation of subgrain boundaries during high strain rate deformation.A physical relationship between grain refinement and dislocation evolution is established and incorporated into the crystal plasticity constitutive model,where the spatial position of the subgrain boundaries can be determined by the energy minimization path.The developed constitutive model is implemented to simulate the dynamic compression and tension tests of pure copper by the crystal plasticity finite element method.Results show that the developed grain refinement model based on the dislocation entanglement gives good agreement with the experimental data validating its feasibility and rationality.The strengthening effect of grain refinement on the flow stress of metals at high strain rates depends on the competition between the strengthening of grain boundary and the softening of dislocation consumption during grain refinement.Further,a series of dynamic compressions are performed on copper samples with different grain sizes to explore the strengthening effect of grain refinement.The corresponding mechanisms of strengthening are analyzed and their respective contributions are also discussed in detail.The developed model can accurately predict the grain refinement of metals and capture its effect on strain hardening under high strain rate deformation.
