Homogeneous crystal nucleation is prone to formation of defects and often experiences heterogeneities,the inferences of which are crucial in processing crystalline materials and controlling their physical properties. ...Homogeneous crystal nucleation is prone to formation of defects and often experiences heterogeneities,the inferences of which are crucial in processing crystalline materials and controlling their physical properties. It has been debated in literature whether the associated heterogeneities are an integral part of the homogenous nucleation. In this study by integrating a probabilistic approach with large-scale molecular dynamics simulations based on the most advanced high-temperature interatomic potentials, we attempt to address the ambiguity over the sources and mechanisms of heterogeneities in homogenous nucleation during solidification of pure melts. Different classes of structured metals are investigated for this purpose,including face-centered cubic aluminum, body-centered cubic iron, and hexagonal close-packed magnesium. The results reveal, regardless of the element type or the solidified crystal structure, that the densification process of liquid metals is accompanied by short-range orderings of atoms prior to the formation of crystals, controlling the heterogeneities during homogenous nucleation.展开更多
A new multivariate population balance modeling for the homogenous nucleation from bismuth vapor is tested against experimental results. However, the small differences of some key parameters could lead to the ill-posed...A new multivariate population balance modeling for the homogenous nucleation from bismuth vapor is tested against experimental results. However, the small differences of some key parameters could lead to the ill-posed problem, such as the surface tension. In this study, the parameter fluctuations set according to the response surface method are employed in the population balance simulation to identify their importance. Subsequently, the quadratic polynomials are established to replace the simulation and the fluctuations are evaluated with the characteristic parameters of particle evolution. It is found that the surface tension tends to be the most significant factor determining the particle evolution, which is also influenced by the coefficient in condensation rates and fractal dimension in the coagulation. To get more accurate modeling and key parameters, the comprehensive sum of mean square error is calculated based on all the fluctuations and the appropriate value for the surface tension is 0.466 N/m.展开更多
The size, number, morphology and type of inclusion particles are the key factors to estimate the quality of steel product. Although considerable efforts have been made in the mathematical modeling of inclusion growth,...The size, number, morphology and type of inclusion particles are the key factors to estimate the quality of steel product. Although considerable efforts have been made in the mathematical modeling of inclusion growth, few papers were involved in inclusionts nucleation and collision-growth, and all the existing researches about the behaviors of magnesia inclusion were based on the experiments. Thus, a mathematical model was developed to investigate the nucleation, Ostwald ripening and collision-growth of magnesia inclusion in the molten steel. Numerical results showed that the predicted particle size distributions are consistent with the previous experimental data. For the magnesia inclusions smaller than 100 nm, Brownian collision is the main collision modes. For the inclusions ranging from 0.1 to 10μm, Brownian collision and turbulent collision are the main collision modes. For the inclusions ranging from 10 to 100μm, turbulent collision and Stokes collision are the main collision modes. Thus, the strong turbulent flow can decrease the peak-value diameter of the magnesia inclusion effectively.展开更多
The goethite residue generated from zinc hydrometallurgy is classified as hazardous solid waste,produced in large quantities,and results in significant zinc loss.The study was conducted on removing iron from FeSO_(4)-...The goethite residue generated from zinc hydrometallurgy is classified as hazardous solid waste,produced in large quantities,and results in significant zinc loss.The study was conducted on removing iron from FeSO_(4)-ZnSO_(4) solution,employing seed-induced nucleation methods.Analysis of the iron removal rate,residue structure,morphology,and elemental composition involved ICP,XRD,FT-IR,and SEM.The existing state of zinc was investigated by combining step-by-step dissolution using hydrochloric acid.Concurrently,iron removal tests were extended to industrial solutions to assess the influence of seeds and solution pH on zinc loss and residue yield.The results revealed that seed addition increased the iron removal rate by 3%,elevated the residual iron content by 6.39%,and mitigated zinc loss by 29.55%in the simulated solution.Seed-induced nucleation prevented excessive nuclei formation,fostering crystal stable growth and high crystallinity.In addition,the zinc content of surface adsorption and crystal internal embedding in the residue was determined,and the zinc distribution on the surface was dense.In contrast,the total amount of zinc within the crystal was higher.The test results in the industrial solution demonstrated that the introduction of seeds expanded the pH range for goethite formation and growth,and the zinc loss per ton of iron removed was reduced by 50.91 kg(34.12%)and the iron residue reduced by 0.17 t(8.72%).展开更多
Isotactic polypropylene （iPP） nanodroplets were prepared by using the classical droplet method in this study. The formation of nanodroplets allowed the controlled observation of polymer nucleation as well as access ...Isotactic polypropylene （iPP） nanodroplets were prepared by using the classical droplet method in this study. The formation of nanodroplets allowed the controlled observation of polymer nucleation as well as access to crystal growth at exceptionally high supercooling in /PP. Three cases including the heterogeneous nucleation and fast crystallization in iPP droplets, the formation of multiple independent homogeneous nuclei within a single droplet and a single nucleus within a single droplet were detected by using atomic force microscopy （AFM） during gradually cooling after remelting the nanodroplets. Moreover, it is found that when the volume of droplet is larger than the value of ca. 130000 nm3, the first case was observed. Otherwise, the latter two cases appeared. The temperature at which the onset of nucleation was observed in individual droplets was found to be mainly dependent on height of the droplets when the size scale of the droplet is comparable to the size of the critical nucleus in at least one dimension, which indicates the nucleation behavior under confinement.展开更多
The hydrogen effect on the nucleation and motion of dislocations in single-crystal bcc Fe with(110)surface was investigated by both nanoindentation experiments and discrete dislocation dynamics(DDD)simulation.The resu...The hydrogen effect on the nucleation and motion of dislocations in single-crystal bcc Fe with(110)surface was investigated by both nanoindentation experiments and discrete dislocation dynamics(DDD)simulation.The results of nanoindentation experiments showed that the pop-in load decreased evidently for the electrochemical hydrogen charging specimen,indicating that the dislocation nucleation strength might be reduced by hydrogen.In addition,the decrease of hardness due to hydrogen charging was also captured,implying that the dislocation motion might be promoted by hydrogen.By incorporating the effect of hydrogen on dislocation core energy,a DDD model was specifically proposed to investigate the influence of hydrogen on dislocation nucleation and motion.The results of DDD simulation revealed that under the effect of hydrogen,the dislocation nucleation strength is decreased and the motion of dislocation is promoted.展开更多
Differential fast scanning calorimetry（DFSC） was employed on the study of self-nucleation behavior of poly（butylene succinate）（PBS）.The ultra-fast cooling ability of DFSC allows investigating the effect of self-...Differential fast scanning calorimetry（DFSC） was employed on the study of self-nucleation behavior of poly（butylene succinate）（PBS）.The ultra-fast cooling ability of DFSC allows investigating the effect of self-nucleation on the isothermal crystallization kinetics over a wide temperature range.Crystallization half-time,instead of crystallization peak temperature,was used to describe the self-nucleation behavior,and the self-nucleation domain for the samples crystallized at different temperatures was determined.Due to the competition between homogenous nucleation and self-nuclei,the effect of self-nucleation was less pronounced at high supercooling than that for the sample isothermally crystallized at higher temperature.An efficiency scale to judge the efficiency of nucleating agents from the crystallization half-time was also introduced in this work.展开更多
The complete elimination of methylammonium(MA)cations in Sn-Pb composites can extend their light and thermal stabilities.Unfortunately,MA-free Sn-Pb alloyed perovskite thin films suffer from wrinkled surfaces and poor...The complete elimination of methylammonium(MA)cations in Sn-Pb composites can extend their light and thermal stabilities.Unfortunately,MA-free Sn-Pb alloyed perovskite thin films suffer from wrinkled surfaces and poor crystallization,due to the coexistence of mixed intermediate phases.Here,we report an additive strategy for finely regulating the impurities in the intermediate phase of Cs_(0.25)FA_(0.75)Pb_(0.6)Sn_(0.4)I_(3)and,thereby,obtaining high-performance solar cells.We introduced d-homoserine lactone hydrochloride(D-HLH)to form hydrogen bonds and strong Pb-O/Sn-O bonds with perovskite precursors,thereby weakening the incomplete complexation effect between polar aprotic solvents(e.g.,DMSO)and organic(FAI)or inorganic(CsI,PbI_(2),and SnI_(2))components,and balancing their nucleation processes.This treatment completely transformed mixed intermediate phases into pure preformed perovskite nuclei prior to thermal anneal-ing.Besides,this D-HLH substantially inhibited the oxidation of Sn^(2+) species.This strategy generated a record efficiency of 21.61%,with a Voc of 0.88 V for an MA-free Sn-Pb device,and an efficiency of 23.82%for its tandem device.The unencapsulated devices displayed impressive thermal stability at 85℃ for 300 h and much improved continuous operation stability at MPP for 120 h.展开更多
SiC-YAG(Y3Al5O12) ceramic composite powders were prepared by co-precipitation coating method. Mechanism of co-precipitation coating of SiC powders with Y3+ and Al3+ precursors was investigated. If the concentration of...SiC-YAG(Y3Al5O12) ceramic composite powders were prepared by co-precipitation coating method. Mechanism of co-precipitation coating of SiC powders with Y3+ and Al3+ precursors was investigated. If the concentration of [OH-] ion in the solution is controlled within the range between critical values for heterogeneous nucleation and homogeneous nucleation, Y3+ and Al3+ precipitation precursors can be coated on the surface of SiC particles. Y3+ and Al3+ precipitation precursors transform into YAG phase after calcining at 1000 ℃ without the formation of YAM and YAP phases. The formation temperature of YAG phase is about 600 ℃ lower than that of conventional powder mixing method. The effect of pH value of the solution and precipitant titration rate on coating quality of SiC-YAG composite powders was also studied. The results show that co-precipitation coating can be realized at a final pH of 9 and a precipitant titration rate of 5 ml·min-1.展开更多
Sodium/Potassium(Na/K)metal anodes have been considered as the promising anodes for next-generation Na/K secondary batteries owing to their ultrahigh specific capacity,low redox potential and low cost.However,their pr...Sodium/Potassium(Na/K)metal anodes have been considered as the promising anodes for next-generation Na/K secondary batteries owing to their ultrahigh specific capacity,low redox potential and low cost.However,their practical application is still hampered due to unstable solid electrolyte interphase,infinite volume change,and dendrite growth.Herein,we design a 3D-Na_(3)Bi/3D-K_(3)Bi alloy host which enables the homogeneous and heterogeneous nucleation growth of Na/K metal.The unique structure with periodic alternating of electron and ion conductivity improves the mass transfer kinetics and prevents the volume expansion during cycling.Meanwhile,the sodiophilicity of Na_(3)Bi/potassiophilicity of K_(3)Bi framework can avoid dendritic growth.Cycling lifespans over 700 h with 1 mAh cm^(−2)for 3D-Na_(3)Bi@Na electrode and about 450 h with 1 mAh cm^(−2)for 3D-K_(3)Bi@K electrode are achieved,respectively.3D-Na_(3)Bi@Na||Na_(3)V_(2)(PO_(4))3 full battery shows sustainable cycle performance over 400 cycles.This design provides a simple but effective approach for achieving safety of sodium/potassium metal anodes.展开更多
The paper addresses some of the problems surrounding the relation between ice core chemical signals and atmospheric chemical composition in polar areas. The topic is important as the reconstruction of past climate and...The paper addresses some of the problems surrounding the relation between ice core chemical signals and atmospheric chemical composition in polar areas. The topic is important as the reconstruction of past climate and past atmospheric chemical composition is based on the assumption that chemical concentrations in the air, snow, firn and ice core are correlated. Ice core interpretation of aerosol is more straightforward than that of reactive gases. The transfer functions of gaseous species strongly interacting with ice are complex and additional field and laboratory experiments are required. Ice core chemical signals depend on the chemical composition of precipitations, which are related to the physics of precipitation formation, the chemical composition of the atmosphere, and post-depositional processes. Published papers reporting data on the chemical composition of snow seldom consider the fact that crystal formation and growth in cloud (rimed or unrimed) or near the ground (clear-sky precipitations), hoar-frost formation and surface riming determine different chemical concentrations, even assuming constant background concentration in the atmosphere. This paper discusses the physical and chemical processes affecting the formation of precipitations in polar areas, and the process of scavenging gases from non-growing and growing crystals. Attention is mainly focused on the processes involving nitrate anion in snow, hoar frost and firn. Knowledge of the chemical relationship between surface snow and atmospheric chemical concentration could be enhanced by considering specific events, such as snow falling from cloud, clear sky precipitation, and surface hoar or riming surface, with simultaneous air sampling. In conclusion, field and laboratory experiments are still required to study the scavenging processes during crystal formation.展开更多
1.Introduction Al-Zn-Mg-Cu alloy is a typical age-hardening aluminum alloy,its strength and toughness are significantly influenced by precipita-tion behavior.The nucleation mechanisms of precipitates in this alloy are...1.Introduction Al-Zn-Mg-Cu alloy is a typical age-hardening aluminum alloy,its strength and toughness are significantly influenced by precipita-tion behavior.The nucleation mechanisms of precipitates in this alloy are generally categorized into homogeneous and heterogeneous nucleation.Homogeneous nucleation relies on structural and energy fluctuations within the solution to generate the driving force necessary for direct nucleation.展开更多
The primary objective of this study is to thoroughly explore the processes of homogeneous nucleation in alloys and heterogeneous nucleation in organic heterostructures,with the ultimate goal of gaining precise control...The primary objective of this study is to thoroughly explore the processes of homogeneous nucleation in alloys and heterogeneous nucleation in organic heterostructures,with the ultimate goal of gaining precise control over the selection between two nucleation mechanisms.By using Perylene(Pe)as the donor and isomers of tetrachlorophthalonitrile as the acceptors,alloys with continuously tunable luminescent colors were successfully synthesized in a one-step process.Additionally,using two-step synthesis,microcrystals of triblock and semi-core/shell heterostructures,composed of cocrystals and alloys,were successfully prepared.Notably,the formation of the two types of heterostructures was elucidated,emphasizing the kinetic and thermodynamic effects on the nucleation of cocrystals.Additionally,the heterostructures facilitate the construction of optical logic gates with photonic coding.展开更多
The homogeneous nucleation with subsequent spontaneous condensation of water, pentanol, and ethanol xupors in a carrier gas are investigated experimentally and theoretically in the expansion part of a shock tube. The ...The homogeneous nucleation with subsequent spontaneous condensation of water, pentanol, and ethanol xupors in a carrier gas are investigated experimentally and theoretically in the expansion part of a shock tube. The precise pressure and Mcw measurements give additional information about the wetness, so that the nucleation and condensation rates which are closely coupled for stronger expansion rates are determined more accurately. Predictions of the principle of the minimum of entropy production are compared with experiments performed for water, ethanol and pentanol at different pressures.展开更多
Our objective is a better understanding of the role of physical properties of real fluids in the thermodynamics of cavitation in impure water. An extension to the classical homogenous nucleation theory suitable for mi...Our objective is a better understanding of the role of physical properties of real fluids in the thermodynamics of cavitation in impure water. An extension to the classical homogenous nucleation theory suitable for mixtures is presented in attempt to address the discrepancy between the theoretical predictions and practical observations of cavitation rates in water at normal temperatures. The extension takes into account the non-equilibrium (dissipative) effects involved in nuclei formation through a substance dependent correction coefficient to be determined experimentally. The theory of thermodynamic fluctuations is applied to derive the work of formation of a bubble nucleus. The value of the correction coefficient is estimated using preliminary experimental data from a convergent-divergent nozzle. An application of the results to the numerical prediction of the cavitation zones in a radial-flow water pump is shown.展开更多
基金financially supported by the National Science Foundation (Nos.NSF-CMMI 1855491 and NSF-CMMI 2031800)。
文摘Homogeneous crystal nucleation is prone to formation of defects and often experiences heterogeneities,the inferences of which are crucial in processing crystalline materials and controlling their physical properties. It has been debated in literature whether the associated heterogeneities are an integral part of the homogenous nucleation. In this study by integrating a probabilistic approach with large-scale molecular dynamics simulations based on the most advanced high-temperature interatomic potentials, we attempt to address the ambiguity over the sources and mechanisms of heterogeneities in homogenous nucleation during solidification of pure melts. Different classes of structured metals are investigated for this purpose,including face-centered cubic aluminum, body-centered cubic iron, and hexagonal close-packed magnesium. The results reveal, regardless of the element type or the solidified crystal structure, that the densification process of liquid metals is accompanied by short-range orderings of atoms prior to the formation of crystals, controlling the heterogeneities during homogenous nucleation.
基金supported by the National Natural Science Foundation of China(grant Nos.U2330204 and 52025063)the German Research Foundation(DFG)within the research group 2284(project No.262219004).
文摘A new multivariate population balance modeling for the homogenous nucleation from bismuth vapor is tested against experimental results. However, the small differences of some key parameters could lead to the ill-posed problem, such as the surface tension. In this study, the parameter fluctuations set according to the response surface method are employed in the population balance simulation to identify their importance. Subsequently, the quadratic polynomials are established to replace the simulation and the fluctuations are evaluated with the characteristic parameters of particle evolution. It is found that the surface tension tends to be the most significant factor determining the particle evolution, which is also influenced by the coefficient in condensation rates and fractal dimension in the coagulation. To get more accurate modeling and key parameters, the comprehensive sum of mean square error is calculated based on all the fluctuations and the appropriate value for the surface tension is 0.466 N/m.
基金the financial support of the project from the National High-Tech R&D Program of China (No. 2009AA03Z530)the National Natural Science Foundation of China and Shanghai Baosteel(No. 50834010)the Fundamental Research Funds for the Central Universities (N100409007)
文摘The size, number, morphology and type of inclusion particles are the key factors to estimate the quality of steel product. Although considerable efforts have been made in the mathematical modeling of inclusion growth, few papers were involved in inclusionts nucleation and collision-growth, and all the existing researches about the behaviors of magnesia inclusion were based on the experiments. Thus, a mathematical model was developed to investigate the nucleation, Ostwald ripening and collision-growth of magnesia inclusion in the molten steel. Numerical results showed that the predicted particle size distributions are consistent with the previous experimental data. For the magnesia inclusions smaller than 100 nm, Brownian collision is the main collision modes. For the inclusions ranging from 0.1 to 10μm, Brownian collision and turbulent collision are the main collision modes. For the inclusions ranging from 10 to 100μm, turbulent collision and Stokes collision are the main collision modes. Thus, the strong turbulent flow can decrease the peak-value diameter of the magnesia inclusion effectively.
基金Project(2018YFC1900403) supported by the National Key Research and Development Program of ChinaProject(CX20210197) supported by the Postgraduate Scientific Research Innovation Project of Hunan Province,China+1 种基金Project(202206370103) supported by the China Scholarship CouncilProject(2021zzts0115) supported by the Fundamental Research Funds for the Central Universities,China。
文摘The goethite residue generated from zinc hydrometallurgy is classified as hazardous solid waste,produced in large quantities,and results in significant zinc loss.The study was conducted on removing iron from FeSO_(4)-ZnSO_(4) solution,employing seed-induced nucleation methods.Analysis of the iron removal rate,residue structure,morphology,and elemental composition involved ICP,XRD,FT-IR,and SEM.The existing state of zinc was investigated by combining step-by-step dissolution using hydrochloric acid.Concurrently,iron removal tests were extended to industrial solutions to assess the influence of seeds and solution pH on zinc loss and residue yield.The results revealed that seed addition increased the iron removal rate by 3%,elevated the residual iron content by 6.39%,and mitigated zinc loss by 29.55%in the simulated solution.Seed-induced nucleation prevented excessive nuclei formation,fostering crystal stable growth and high crystallinity.In addition,the zinc content of surface adsorption and crystal internal embedding in the residue was determined,and the zinc distribution on the surface was dense.In contrast,the total amount of zinc within the crystal was higher.The test results in the industrial solution demonstrated that the introduction of seeds expanded the pH range for goethite formation and growth,and the zinc loss per ton of iron removed was reduced by 50.91 kg(34.12%)and the iron residue reduced by 0.17 t(8.72%).
基金supported by the National Natural Science Foundation of China (No. 20804051)the Natural Science Foundation of Hebei Province (Nos. B2010001055, E2011210059)
文摘Isotactic polypropylene （iPP） nanodroplets were prepared by using the classical droplet method in this study. The formation of nanodroplets allowed the controlled observation of polymer nucleation as well as access to crystal growth at exceptionally high supercooling in /PP. Three cases including the heterogeneous nucleation and fast crystallization in iPP droplets, the formation of multiple independent homogeneous nuclei within a single droplet and a single nucleus within a single droplet were detected by using atomic force microscopy （AFM） during gradually cooling after remelting the nanodroplets. Moreover, it is found that when the volume of droplet is larger than the value of ca. 130000 nm3, the first case was observed. Otherwise, the latter two cases appeared. The temperature at which the onset of nucleation was observed in individual droplets was found to be mainly dependent on height of the droplets when the size scale of the droplet is comparable to the size of the critical nucleus in at least one dimension, which indicates the nucleation behavior under confinement.
文摘The hydrogen effect on the nucleation and motion of dislocations in single-crystal bcc Fe with(110)surface was investigated by both nanoindentation experiments and discrete dislocation dynamics(DDD)simulation.The results of nanoindentation experiments showed that the pop-in load decreased evidently for the electrochemical hydrogen charging specimen,indicating that the dislocation nucleation strength might be reduced by hydrogen.In addition,the decrease of hardness due to hydrogen charging was also captured,implying that the dislocation motion might be promoted by hydrogen.By incorporating the effect of hydrogen on dislocation core energy,a DDD model was specifically proposed to investigate the influence of hydrogen on dislocation nucleation and motion.The results of DDD simulation revealed that under the effect of hydrogen,the dislocation nucleation strength is decreased and the motion of dislocation is promoted.
基金financially supported by the National Natural Science Foundation of China(Nos.21474049,51673094 and 21404055)the Shenzhen Science and Technology Innovation Committee(Nos.JCYJ20160531151102203 and JCYJ20160608140827794)Tianshan Scholars Program by Yili Normal University
文摘Differential fast scanning calorimetry（DFSC） was employed on the study of self-nucleation behavior of poly（butylene succinate）（PBS）.The ultra-fast cooling ability of DFSC allows investigating the effect of self-nucleation on the isothermal crystallization kinetics over a wide temperature range.Crystallization half-time,instead of crystallization peak temperature,was used to describe the self-nucleation behavior,and the self-nucleation domain for the samples crystallized at different temperatures was determined.Due to the competition between homogenous nucleation and self-nuclei,the effect of self-nucleation was less pronounced at high supercooling than that for the sample isothermally crystallized at higher temperature.An efficiency scale to judge the efficiency of nucleating agents from the crystallization half-time was also introduced in this work.
基金funded by the Natural Science Foundation of Shanghai(22ZR1428200)the National Natural Science Foundation of China(51950410581)+1 种基金the Shanghai Government(20JC141500)and CATL-SJTU joint funding.
文摘The complete elimination of methylammonium(MA)cations in Sn-Pb composites can extend their light and thermal stabilities.Unfortunately,MA-free Sn-Pb alloyed perovskite thin films suffer from wrinkled surfaces and poor crystallization,due to the coexistence of mixed intermediate phases.Here,we report an additive strategy for finely regulating the impurities in the intermediate phase of Cs_(0.25)FA_(0.75)Pb_(0.6)Sn_(0.4)I_(3)and,thereby,obtaining high-performance solar cells.We introduced d-homoserine lactone hydrochloride(D-HLH)to form hydrogen bonds and strong Pb-O/Sn-O bonds with perovskite precursors,thereby weakening the incomplete complexation effect between polar aprotic solvents(e.g.,DMSO)and organic(FAI)or inorganic(CsI,PbI_(2),and SnI_(2))components,and balancing their nucleation processes.This treatment completely transformed mixed intermediate phases into pure preformed perovskite nuclei prior to thermal anneal-ing.Besides,this D-HLH substantially inhibited the oxidation of Sn^(2+) species.This strategy generated a record efficiency of 21.61%,with a Voc of 0.88 V for an MA-free Sn-Pb device,and an efficiency of 23.82%for its tandem device.The unencapsulated devices displayed impressive thermal stability at 85℃ for 300 h and much improved continuous operation stability at MPP for 120 h.
文摘SiC-YAG(Y3Al5O12) ceramic composite powders were prepared by co-precipitation coating method. Mechanism of co-precipitation coating of SiC powders with Y3+ and Al3+ precursors was investigated. If the concentration of [OH-] ion in the solution is controlled within the range between critical values for heterogeneous nucleation and homogeneous nucleation, Y3+ and Al3+ precipitation precursors can be coated on the surface of SiC particles. Y3+ and Al3+ precipitation precursors transform into YAG phase after calcining at 1000 ℃ without the formation of YAM and YAP phases. The formation temperature of YAG phase is about 600 ℃ lower than that of conventional powder mixing method. The effect of pH value of the solution and precipitant titration rate on coating quality of SiC-YAG composite powders was also studied. The results show that co-precipitation coating can be realized at a final pH of 9 and a precipitant titration rate of 5 ml·min-1.
基金This work was supported by the National Natural Science Foundation of China(Nos.51925207,U1910210,51872277,22005292,52002083)the National Synchrotron Radiation Laboratory(KY2060000173)+1 种基金the Joint Fund of the Yulin University and the Dalian National Laboratory for Clean Energy(Grant.YLU-DNL Fund 2021002)the Fundamental Research Funds for the Central Universities(WK2060140026).
文摘Sodium/Potassium(Na/K)metal anodes have been considered as the promising anodes for next-generation Na/K secondary batteries owing to their ultrahigh specific capacity,low redox potential and low cost.However,their practical application is still hampered due to unstable solid electrolyte interphase,infinite volume change,and dendrite growth.Herein,we design a 3D-Na_(3)Bi/3D-K_(3)Bi alloy host which enables the homogeneous and heterogeneous nucleation growth of Na/K metal.The unique structure with periodic alternating of electron and ion conductivity improves the mass transfer kinetics and prevents the volume expansion during cycling.Meanwhile,the sodiophilicity of Na_(3)Bi/potassiophilicity of K_(3)Bi framework can avoid dendritic growth.Cycling lifespans over 700 h with 1 mAh cm^(−2)for 3D-Na_(3)Bi@Na electrode and about 450 h with 1 mAh cm^(−2)for 3D-K_(3)Bi@K electrode are achieved,respectively.3D-Na_(3)Bi@Na||Na_(3)V_(2)(PO_(4))3 full battery shows sustainable cycle performance over 400 cycles.This design provides a simple but effective approach for achieving safety of sodium/potassium metal anodes.
文摘The paper addresses some of the problems surrounding the relation between ice core chemical signals and atmospheric chemical composition in polar areas. The topic is important as the reconstruction of past climate and past atmospheric chemical composition is based on the assumption that chemical concentrations in the air, snow, firn and ice core are correlated. Ice core interpretation of aerosol is more straightforward than that of reactive gases. The transfer functions of gaseous species strongly interacting with ice are complex and additional field and laboratory experiments are required. Ice core chemical signals depend on the chemical composition of precipitations, which are related to the physics of precipitation formation, the chemical composition of the atmosphere, and post-depositional processes. Published papers reporting data on the chemical composition of snow seldom consider the fact that crystal formation and growth in cloud (rimed or unrimed) or near the ground (clear-sky precipitations), hoar-frost formation and surface riming determine different chemical concentrations, even assuming constant background concentration in the atmosphere. This paper discusses the physical and chemical processes affecting the formation of precipitations in polar areas, and the process of scavenging gases from non-growing and growing crystals. Attention is mainly focused on the processes involving nitrate anion in snow, hoar frost and firn. Knowledge of the chemical relationship between surface snow and atmospheric chemical concentration could be enhanced by considering specific events, such as snow falling from cloud, clear sky precipitation, and surface hoar or riming surface, with simultaneous air sampling. In conclusion, field and laboratory experiments are still required to study the scavenging processes during crystal formation.
基金supported by the National Natural Science Foundation of China(Grant Nos.U21A20130 and 52475357).
文摘1.Introduction Al-Zn-Mg-Cu alloy is a typical age-hardening aluminum alloy,its strength and toughness are significantly influenced by precipita-tion behavior.The nucleation mechanisms of precipitates in this alloy are generally categorized into homogeneous and heterogeneous nucleation.Homogeneous nucleation relies on structural and energy fluctuations within the solution to generate the driving force necessary for direct nucleation.
基金support from the Natural Science Foundation of Jiangsu Province(Nos.BK20230010,BK20221362)the National Natural Science Foundation of China(Nos.52173177,52473314,22475122)+1 种基金the Natural Science Foundation of Shandong Province(ZR2020MB054)the Collaborative Innovation Center of Suzhou Nano Science&Technology.
文摘The primary objective of this study is to thoroughly explore the processes of homogeneous nucleation in alloys and heterogeneous nucleation in organic heterostructures,with the ultimate goal of gaining precise control over the selection between two nucleation mechanisms.By using Perylene(Pe)as the donor and isomers of tetrachlorophthalonitrile as the acceptors,alloys with continuously tunable luminescent colors were successfully synthesized in a one-step process.Additionally,using two-step synthesis,microcrystals of triblock and semi-core/shell heterostructures,composed of cocrystals and alloys,were successfully prepared.Notably,the formation of the two types of heterostructures was elucidated,emphasizing the kinetic and thermodynamic effects on the nucleation of cocrystals.Additionally,the heterostructures facilitate the construction of optical logic gates with photonic coding.
文摘The homogeneous nucleation with subsequent spontaneous condensation of water, pentanol, and ethanol xupors in a carrier gas are investigated experimentally and theoretically in the expansion part of a shock tube. The precise pressure and Mcw measurements give additional information about the wetness, so that the nucleation and condensation rates which are closely coupled for stronger expansion rates are determined more accurately. Predictions of the principle of the minimum of entropy production are compared with experiments performed for water, ethanol and pentanol at different pressures.
文摘Our objective is a better understanding of the role of physical properties of real fluids in the thermodynamics of cavitation in impure water. An extension to the classical homogenous nucleation theory suitable for mixtures is presented in attempt to address the discrepancy between the theoretical predictions and practical observations of cavitation rates in water at normal temperatures. The extension takes into account the non-equilibrium (dissipative) effects involved in nuclei formation through a substance dependent correction coefficient to be determined experimentally. The theory of thermodynamic fluctuations is applied to derive the work of formation of a bubble nucleus. The value of the correction coefficient is estimated using preliminary experimental data from a convergent-divergent nozzle. An application of the results to the numerical prediction of the cavitation zones in a radial-flow water pump is shown.
