Lithium metal batteries represent promising candidates for high-energy-density batteries, however, many challenges must still be overcome,e.g., interface instability and dendrite growth. In this work, nano silica aero...Lithium metal batteries represent promising candidates for high-energy-density batteries, however, many challenges must still be overcome,e.g., interface instability and dendrite growth. In this work, nano silica aerogel was employed to generate a hybrid film with high lithium ion conductivity(0.6 mS cm^(-1)at room temperature) via an in situ crosslinking reaction. TOF-SIMS profile analysis has revealed conversion mechanism of hybrid film to Li–Si alloy/Li F biphasic interface layer, suggesting that the Li–Si alloy and Li F-rich interface layer promoted rapid Li+transport and shielded the Li anodes from corrosive reactions with electrolyte-derived products. When coupled with nickel-cobalt-manganese-based cathodes, the batteries achieve outstanding capacity retention over 1000 cycles at 1 C. Additionally the developed film coated on Li enabled high coulombic efficiency(99.5%) after long-term cycling when coupled with S cathodes. Overall, the results presented herein confirm an effective strategy for the development of high-energy batteries.展开更多
GaN films grown on(111)Si substrate with different lattice parameters of the AlN buffer layer by metal–organic chemical vapor deposition are studied.The stress states obtained by different test methods are compared a...GaN films grown on(111)Si substrate with different lattice parameters of the AlN buffer layer by metal–organic chemical vapor deposition are studied.The stress states obtained by different test methods are compared and it is found that the lattice parameter of the AlN buffer layer may have a significant effect on the stress state in the initial stage of subsequent GaN film growth.A larger compressive stress is beneficial to improved surface morphology and crystal quality of GaN film.The results of further orthogonal experiments show that an important factor affecting the lattice parameter is the growth rate of the AlN buffer layer.This work may be helpful for realizing simple GaN-on-Si structures and thus reducing the costs of growth processes.展开更多
Novel models (2× 1) of Si(001)-SiO2 interface structure have been established. The method of the first-principle General Gradient Approximation (GGA) is employed to structurally optimize the established the...Novel models (2× 1) of Si(001)-SiO2 interface structure have been established. The method of the first-principle General Gradient Approximation (GGA) is employed to structurally optimize the established theoretical models under the K-point space of periodic boundary condition. The structures after optimization have been analyzed, and the results show that the interfaces present in disordered state and both Si-O-Si and Si=O structures exist. Meanwhile, the bonding of surface structure is analyzed via the graphics of electron localization function(ELF).展开更多
The microstructure of primary Mg_(2)Si and the interface of Mg_(2)Si/α-Mg modified by Sn and Sb elements in an as-cast Mg-5Sn-2Si-1.5Al-1Zn-0.8Sb(wt.%) alloy were investigated.In the primary Mg_(2)Si phase not only t...The microstructure of primary Mg_(2)Si and the interface of Mg_(2)Si/α-Mg modified by Sn and Sb elements in an as-cast Mg-5Sn-2Si-1.5Al-1Zn-0.8Sb(wt.%) alloy were investigated.In the primary Mg_(2)Si phase not only the Si atoms but also the Mg atoms could be substituted by Sn and Sb atoms,resulting in the slightly reduced lattice constant a of 0.627 nm.An OR of Mg_(2)Si phase and α-Mg in the form of[001]Mg_(2)Si‖[01■1]α,(220)Mg_(2)Si‖(0■12)αwas discovered.Between primary Mg_(2)Si phase and α-Mg matrix two transitional nano-particle layers were formed.In the rim region of primary Mg_(2)Si particle,Mg_(2)Sn precipitates sizing from 5 nm to 50 nm were observed.Adjacent to the boundary of primary Mg_(2)Si particle,luxuriant columnar crystals of primary Mg_(2)Sn phase with width of about 25 nm and length of about100 nm were distributed on the α-Mg matrix.The lattice constant of the Mg_(2)Sn precipitate in primary Mg_(2)Si particle was about 0.756 nm.Three ORs between Mg_(2)Sn and Mg_(2)Si were found,in which the Mg_(2)Sn precipitates had strong bonding interfaces with Mg_(2)Si phase.Three new minor ORs between Mg_(2)Sn phase and α-Mg were found.The lattice constant of primary Mg_(2)Sn phase was enlarged to 0.813 nm owing to the solution of Sn and Sb atoms.Primary Mg_(2)Sn had edge-to-edge interfaces with α-Mg.Therefore,the primary Mg_(2)Si particle and α-Mg were united and the interfacial adhesion was improved by the two nano-particles layers of Mg_(2)Sn phase.展开更多
The electron transport behavior across the interface plays an important role in determining the performance of op- toelectronic devices based on heterojunctions. Here through growing CdS thin film on silicon nanoporou...The electron transport behavior across the interface plays an important role in determining the performance of op- toelectronic devices based on heterojunctions. Here through growing CdS thin film on silicon nanoporous pillar array, an untraditional, nonplanar, and multi-interface CdS/Si nanoheterojunction is prepared. The current density versus voltage curve is measured and an obvious rectification effect is observed. Based on the fitting results and model analyses on the forward and reverse conduction characteristics, the electron transport mechanism under low forward bias, high forward bias, and reverse bias are attributed to the Ohmic regime, space-charge-limited current regime, and modified Poole-Frenkel regime respectively. The forward and reverse electrical behaviors are found to be highly related to the distribution of inter- facial trap states and the existence of localized electric field respectively. These results might be helpful for optimizing the preparing procedures to realize high-performance silicon-based CdS optoelectronic devices.展开更多
The holes induced by ionizing radiation or carrier injection can depassivate saturated interface defects.The depassivation of these defects suggests that the deep levels associated with the defects are reactivated,aff...The holes induced by ionizing radiation or carrier injection can depassivate saturated interface defects.The depassivation of these defects suggests that the deep levels associated with the defects are reactivated,affecting the performance of devices.This work simulates the depassivation reactions between holes and passivated amorphous-SiO_(2)/Si interface defects(HP_(b)+h→P_(b)+H^(+)).The climbing image nudged elastic band method is used to calculate the reaction curves and the barriers.In addition,the atomic charges of the initial and final structures are analyzed by the Bader charge method.It is shown that more than one hole is trapped by the defects,which is implied by the reduction in the total number of valence electrons on the active atoms.The results indicate that the depassivation of the defects by the holes actually occurs in three steps.In the first step,a hole is captured by the passivated defect,resulting in the stretching of the Si-H bond.In the second step,the defect captures one more hole,which may contribute to the breaking of the Si-H bond.The H atom is released as a proton and the Si atom is three-coordinated and positively charged.In the third step,an electron is captured by the Si atom,and the Si atom becomes neutral.In this step,a Pb-type defect is reactivated.展开更多
It is well known that in the process of thermal oxidation of silicon,there are P_(b)-type defects at amorphous silicon dioxide/silicon(a-SiO_(2)/Si)interface due to strain.These defects have a very important impact on...It is well known that in the process of thermal oxidation of silicon,there are P_(b)-type defects at amorphous silicon dioxide/silicon(a-SiO_(2)/Si)interface due to strain.These defects have a very important impact on the performance and reliability of semiconductor devices.In the process of passivation,hydrogen is usually used to inactivate P_(b)-type defects by the reaction P_(b)+H_(2)→P_(b)H+H.At the same time,P_(b)H centers dissociate according to the chemical reaction P_(b)H→P_(b)+H.Therefore,it is of great significance to study the balance of the passivation and dissociation.In this work,the reaction mechanisms of passivation and dissociation of the P_(b)-type defects are investigated by first-principles calculations.The reaction rates of the passivation and dissociation are calculated by the climbing image-nudged elastic band(CI-NEB)method and harmonic transition state theory(HTST).By coupling the rate equations of the passivation and dissociation reactions,the equilibrium density ratio of the saturated interfacial dangling bonds and interfacial defects(P_(b),P_(b)0,and P_(b)1)at different temperatures is calculated.展开更多
By using newly developed CuNi5~25Ti16~28 B rapldly solidifled brazing filler the joining of Si3 N4/1.25Cr-0.5Mo steel has been carried out with interlayer method. If employing the interlayer structure of steel (0.2 mm...By using newly developed CuNi5~25Ti16~28 B rapldly solidifled brazing filler the joining of Si3 N4/1.25Cr-0.5Mo steel has been carried out with interlayer method. If employing the interlayer structure of steel (0.2 mm)/W (2.0 mm)/Ni(0.2 mm), the joint strength can be increased greatly compared with employing that of Ni/W/Ni, and the three point bend strength of the Joint shows the value of 261 MPa. The metallurgical behaviour at the interface between Si3N4 and the interlayer has been studied. It is found that Fe participated in the interfacial reactions between Si3N4 and the brazing filler at the Si3N4/steel (0.2 mm) interface and the compound Fe5Si3 was produced. However, since the reactions of Fe with the active Ti are weaker than those of Ni with Ti, the normal inter facial reactions were still assured at the interface of Si3N4/steel (0.2 mm) instead of Si3N4/Ni (0.2 mm), resulting in the improvement of the joint strength. The mechanism of the formation of Fe5Si3 is also discussed. Finally, some ideas to further ameliorate and simplify the interlayer structure are put forward.展开更多
A model Cu-AlN composite has been prepared by ion implantation technique and annealing. The atomic configuration and lattice relationship of a low-energy inherent interface(11)Cn//(0001)AlN were studied by using trans...A model Cu-AlN composite has been prepared by ion implantation technique and annealing. The atomic configuration and lattice relationship of a low-energy inherent interface(11)Cn//(0001)AlN were studied by using transmission electron microscopy and geometrical modelling. By analysing the dichromatic pattern of the composite,a primary structural unit of the interface atomic configuration was determined for purpose of HREM image simulations and of studying the structurul relaxation state in the near-interface region.展开更多
Interaction behaviors between Al-Si, Zn-Al alloys and Al2O)3p)/6061Al composite at different heating temperatures were investigated. It is found that Al2O)3p)/6061Al composite can be wetted well by AlSi-1, AlSi-4 and ...Interaction behaviors between Al-Si, Zn-Al alloys and Al2O)3p)/6061Al composite at different heating temperatures were investigated. It is found that Al2O)3p)/6061Al composite can be wetted well by AlSi-1, AlSi-4 and Zn-Al alloys and an interaction layer forms between the alloy and composite during interaction. Little Al-Si alloys remain on the surface when they fully wet the composite and Si element in Al-Si alloy diffuses into composite entirely and assembles in the composite near the interface of Al-Si alloy/composite to form a Si-rich zone. The microstructure in interaction layer with Si penetration is still dense. Much more residual Zn-Al alloy exists on the surface of composite when it wets the composite, and porosities appear at the interface of Zn-Al alloy/composite. The penetration of elements Zn, Cu of Zn-Al alloy into composite leads to the generation of shrinkage cavities in the interaction layer and makes the microstructure of Al2O)3p)/6061Al composite loose.展开更多
基金the support from National Natural Science Foundation of China (22179006)International Science & Technology Cooperation Program of China under Contract No.2019YFE0100200+3 种基金National Natural Science Foundation of China (52072036)NSAF (No.U1930113)Guangdong Key Laboratory of Battery Safety,China (No.2019B121203008)China Postdoctoral Science Foundation (No.2021TQ0034)。
文摘Lithium metal batteries represent promising candidates for high-energy-density batteries, however, many challenges must still be overcome,e.g., interface instability and dendrite growth. In this work, nano silica aerogel was employed to generate a hybrid film with high lithium ion conductivity(0.6 mS cm^(-1)at room temperature) via an in situ crosslinking reaction. TOF-SIMS profile analysis has revealed conversion mechanism of hybrid film to Li–Si alloy/Li F biphasic interface layer, suggesting that the Li–Si alloy and Li F-rich interface layer promoted rapid Li+transport and shielded the Li anodes from corrosive reactions with electrolyte-derived products. When coupled with nickel-cobalt-manganese-based cathodes, the batteries achieve outstanding capacity retention over 1000 cycles at 1 C. Additionally the developed film coated on Li enabled high coulombic efficiency(99.5%) after long-term cycling when coupled with S cathodes. Overall, the results presented herein confirm an effective strategy for the development of high-energy batteries.
基金supported by Beijing Municipal Science&Technology Commission,Administrative Commission of Zhongguancun Science Park(Grant Nos.Z211100007921022 and Z211100004821001)the National Natural Science Foundation of China(Grant Nos.62034008,62074142,62074140,61974162,61904172,61874175,62127807,and U21B2061)+3 种基金Key Research and Development Program of Jiangsu Province(Grant No.BE2021008-1)Beijing Nova Program(Grant No.202093)Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB43030101)Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2019115).
文摘GaN films grown on(111)Si substrate with different lattice parameters of the AlN buffer layer by metal–organic chemical vapor deposition are studied.The stress states obtained by different test methods are compared and it is found that the lattice parameter of the AlN buffer layer may have a significant effect on the stress state in the initial stage of subsequent GaN film growth.A larger compressive stress is beneficial to improved surface morphology and crystal quality of GaN film.The results of further orthogonal experiments show that an important factor affecting the lattice parameter is the growth rate of the AlN buffer layer.This work may be helpful for realizing simple GaN-on-Si structures and thus reducing the costs of growth processes.
基金Supported by the National Grand Fundamental Research 973 Program of China (No. 51310Z07-3) and the Research Program of Application of Sichuan Department of Science and Technology (No. 02GY029-006)
文摘Novel models (2× 1) of Si(001)-SiO2 interface structure have been established. The method of the first-principle General Gradient Approximation (GGA) is employed to structurally optimize the established theoretical models under the K-point space of periodic boundary condition. The structures after optimization have been analyzed, and the results show that the interfaces present in disordered state and both Si-O-Si and Si=O structures exist. Meanwhile, the bonding of surface structure is analyzed via the graphics of electron localization function(ELF).
基金supported by the National Natural Science Foundation of China [51571086]Research Fund for Doctoral Program of Henan Polytechnic University [B2015-14]。
文摘The microstructure of primary Mg_(2)Si and the interface of Mg_(2)Si/α-Mg modified by Sn and Sb elements in an as-cast Mg-5Sn-2Si-1.5Al-1Zn-0.8Sb(wt.%) alloy were investigated.In the primary Mg_(2)Si phase not only the Si atoms but also the Mg atoms could be substituted by Sn and Sb atoms,resulting in the slightly reduced lattice constant a of 0.627 nm.An OR of Mg_(2)Si phase and α-Mg in the form of[001]Mg_(2)Si‖[01■1]α,(220)Mg_(2)Si‖(0■12)αwas discovered.Between primary Mg_(2)Si phase and α-Mg matrix two transitional nano-particle layers were formed.In the rim region of primary Mg_(2)Si particle,Mg_(2)Sn precipitates sizing from 5 nm to 50 nm were observed.Adjacent to the boundary of primary Mg_(2)Si particle,luxuriant columnar crystals of primary Mg_(2)Sn phase with width of about 25 nm and length of about100 nm were distributed on the α-Mg matrix.The lattice constant of the Mg_(2)Sn precipitate in primary Mg_(2)Si particle was about 0.756 nm.Three ORs between Mg_(2)Sn and Mg_(2)Si were found,in which the Mg_(2)Sn precipitates had strong bonding interfaces with Mg_(2)Si phase.Three new minor ORs between Mg_(2)Sn phase and α-Mg were found.The lattice constant of primary Mg_(2)Sn phase was enlarged to 0.813 nm owing to the solution of Sn and Sb atoms.Primary Mg_(2)Sn had edge-to-edge interfaces with α-Mg.Therefore,the primary Mg_(2)Si particle and α-Mg were united and the interfacial adhesion was improved by the two nano-particles layers of Mg_(2)Sn phase.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61176044 and 11074224)the Science and Technology Project for Innovative Scientist of Henan Province,China(Grant No.1142002510017)the Science and Technology Project on Key Problems of Henan Province,China(Grant No.082101510007)
文摘The electron transport behavior across the interface plays an important role in determining the performance of op- toelectronic devices based on heterojunctions. Here through growing CdS thin film on silicon nanoporous pillar array, an untraditional, nonplanar, and multi-interface CdS/Si nanoheterojunction is prepared. The current density versus voltage curve is measured and an obvious rectification effect is observed. Based on the fitting results and model analyses on the forward and reverse conduction characteristics, the electron transport mechanism under low forward bias, high forward bias, and reverse bias are attributed to the Ohmic regime, space-charge-limited current regime, and modified Poole-Frenkel regime respectively. The forward and reverse electrical behaviors are found to be highly related to the distribution of inter- facial trap states and the existence of localized electric field respectively. These results might be helpful for optimizing the preparing procedures to realize high-performance silicon-based CdS optoelectronic devices.
基金Project supported by the Science Challenge Project(Grant No.TZ2016003-1-105)Tianjin Natural Science Foundation,China(Grant No.20JCZDJC00750)the Fundamental Research Funds for the Central Universities—Nankai University(Grant Nos.63211107 and 63201182)。
文摘The holes induced by ionizing radiation or carrier injection can depassivate saturated interface defects.The depassivation of these defects suggests that the deep levels associated with the defects are reactivated,affecting the performance of devices.This work simulates the depassivation reactions between holes and passivated amorphous-SiO_(2)/Si interface defects(HP_(b)+h→P_(b)+H^(+)).The climbing image nudged elastic band method is used to calculate the reaction curves and the barriers.In addition,the atomic charges of the initial and final structures are analyzed by the Bader charge method.It is shown that more than one hole is trapped by the defects,which is implied by the reduction in the total number of valence electrons on the active atoms.The results indicate that the depassivation of the defects by the holes actually occurs in three steps.In the first step,a hole is captured by the passivated defect,resulting in the stretching of the Si-H bond.In the second step,the defect captures one more hole,which may contribute to the breaking of the Si-H bond.The H atom is released as a proton and the Si atom is three-coordinated and positively charged.In the third step,an electron is captured by the Si atom,and the Si atom becomes neutral.In this step,a Pb-type defect is reactivated.
基金Project supported by the Science Challenge Project,China(Grant No.TZ2016003-1-105)the Tianjin Natural Science Foundation,China(Grant No.20JCZDJC00750)the Fundamental Research Funds for the Central Universities,Nankai University(Grant Nos.63211107 and 63201182).
文摘It is well known that in the process of thermal oxidation of silicon,there are P_(b)-type defects at amorphous silicon dioxide/silicon(a-SiO_(2)/Si)interface due to strain.These defects have a very important impact on the performance and reliability of semiconductor devices.In the process of passivation,hydrogen is usually used to inactivate P_(b)-type defects by the reaction P_(b)+H_(2)→P_(b)H+H.At the same time,P_(b)H centers dissociate according to the chemical reaction P_(b)H→P_(b)+H.Therefore,it is of great significance to study the balance of the passivation and dissociation.In this work,the reaction mechanisms of passivation and dissociation of the P_(b)-type defects are investigated by first-principles calculations.The reaction rates of the passivation and dissociation are calculated by the climbing image-nudged elastic band(CI-NEB)method and harmonic transition state theory(HTST).By coupling the rate equations of the passivation and dissociation reactions,the equilibrium density ratio of the saturated interfacial dangling bonds and interfacial defects(P_(b),P_(b)0,and P_(b)1)at different temperatures is calculated.
文摘By using newly developed CuNi5~25Ti16~28 B rapldly solidifled brazing filler the joining of Si3 N4/1.25Cr-0.5Mo steel has been carried out with interlayer method. If employing the interlayer structure of steel (0.2 mm)/W (2.0 mm)/Ni(0.2 mm), the joint strength can be increased greatly compared with employing that of Ni/W/Ni, and the three point bend strength of the Joint shows the value of 261 MPa. The metallurgical behaviour at the interface between Si3N4 and the interlayer has been studied. It is found that Fe participated in the interfacial reactions between Si3N4 and the brazing filler at the Si3N4/steel (0.2 mm) interface and the compound Fe5Si3 was produced. However, since the reactions of Fe with the active Ti are weaker than those of Ni with Ti, the normal inter facial reactions were still assured at the interface of Si3N4/steel (0.2 mm) instead of Si3N4/Ni (0.2 mm), resulting in the improvement of the joint strength. The mechanism of the formation of Fe5Si3 is also discussed. Finally, some ideas to further ameliorate and simplify the interlayer structure are put forward.
文摘A model Cu-AlN composite has been prepared by ion implantation technique and annealing. The atomic configuration and lattice relationship of a low-energy inherent interface(11)Cn//(0001)AlN were studied by using transmission electron microscopy and geometrical modelling. By analysing the dichromatic pattern of the composite,a primary structural unit of the interface atomic configuration was determined for purpose of HREM image simulations and of studying the structurul relaxation state in the near-interface region.
文摘Interaction behaviors between Al-Si, Zn-Al alloys and Al2O)3p)/6061Al composite at different heating temperatures were investigated. It is found that Al2O)3p)/6061Al composite can be wetted well by AlSi-1, AlSi-4 and Zn-Al alloys and an interaction layer forms between the alloy and composite during interaction. Little Al-Si alloys remain on the surface when they fully wet the composite and Si element in Al-Si alloy diffuses into composite entirely and assembles in the composite near the interface of Al-Si alloy/composite to form a Si-rich zone. The microstructure in interaction layer with Si penetration is still dense. Much more residual Zn-Al alloy exists on the surface of composite when it wets the composite, and porosities appear at the interface of Zn-Al alloy/composite. The penetration of elements Zn, Cu of Zn-Al alloy into composite leads to the generation of shrinkage cavities in the interaction layer and makes the microstructure of Al2O)3p)/6061Al composite loose.