Fabrication of high-quality optics puts a strong demand on high-throughput detection of macroscopic bulk defects in optical components.A dark-field line confocal imaging method is proposed with two distinct advantage...Fabrication of high-quality optics puts a strong demand on high-throughput detection of macroscopic bulk defects in optical components.A dark-field line confocal imaging method is proposed with two distinct advantages:(ⅰ)a point-to-line confocal scheme formed by a columnar elliptical mirror and an optical fiber bundle breaks through the constraint on light collection angle and field of view in the traditional line confocal microscopy using an objective,allowing for an extended confocal line field of more than 100 mm while maintaining a light collection angle of 27°;(ⅱ)the bulk defects are independently illuminated as a function of time to eliminate the cross talk in the direction of the confocal slit,thus preserving point confocality and showing the optical section thicknesses to be 162μm in the axial direction,and 19 and 22μm in the orthogonal transverse directions.The experimental results verify that the method has a minimum detectable bulk defect of less than 5μm and an imaging efficiency of 400 mm2/s.The method shows great potential in high-throughput and highsensitivity bulk defects detection.展开更多
Using the first-principles method, we investigate the thermal stability of cation point defects in LaAlO3 bulk and films. The calculated densities of states indicate that cation vacancies and antisites act as acceptor...Using the first-principles method, we investigate the thermal stability of cation point defects in LaAlO3 bulk and films. The calculated densities of states indicate that cation vacancies and antisites act as acceptors. The formation energies show that cation vacancies are energetically favorable in bulk LaAIO3 under O-rich conditions, while the AILa antisites are stable in reducing atmosphere. However, the same behavior does not appear in the case of LaAlO3 films. For LaO-terminated LaAlOa fihns, La or AI vacancies remain energetically favorable under O-rich and O-deficient conditions. For an AlO2-terminated surface, under O-rich condition the La interstitial atom is repelled from the outmost layer after optimization, which releases more stress leading to the decrease of total energy of the system. An AI interstitial atom has a smaller radius so that it can stay in distorted films and becomes more stable under O-deficient conditions, and the Al interstitial atoms can be another possible carrier source contribution to the conductivity of n-type interface under an ultrahigh vacuum. La and Al antisites have similar formation energy regardless of oxygen pressure. The results would be helpful to understand the defect structures of LaAlOa-related materials.展开更多
Here,we report a mixed GAI and MAI(MGM)treatment method by forming a 2D alternating-cation-interlayer(ACI)phase(n=2)perovskite layer on the 3D perovskite,modulating the bulk and interfacial defects in the perovskite f...Here,we report a mixed GAI and MAI(MGM)treatment method by forming a 2D alternating-cation-interlayer(ACI)phase(n=2)perovskite layer on the 3D perovskite,modulating the bulk and interfacial defects in the perovskite films simultaneously,leading to the suppressed nonradiative recombination,longer lifetime,higher mobility,and reduced trap density.Consequently,the devices’performance is enhanced to 24.5%and 18.7%for 0.12 and 64 cm^(2),respectively.In addition,the MGM treatment can be applied to a wide range of perovskite compositions,including MA-,FA-,MAFA-,and CsFAMA-based lead halide perovskites,making it a general method for preparing efficient perovskite solar cells.Without encapsulation,the treated devices show improved stabilities.展开更多
The elastic properties and point defects of thorium monocarbide（ThC） have been studied by means of density functional theory based on the projector-augmented-wave method. The calculated electronic and elastic proper...The elastic properties and point defects of thorium monocarbide（ThC） have been studied by means of density functional theory based on the projector-augmented-wave method. The calculated electronic and elastic properties of ThC are in good agreement with experimental data and previous theoretical results. Five types of point defects have been considered in our study, including the vacancy defect, interstitial defect, antisite defect, schottky defect, and composition-conserving defect. Among these defects, the carbon vacancy defect has the lowest formation energy of 0.29 eV. The second most stable defect（0.49 eV） is one of composition-conserving defects in which one carbon is removed to another carbon site forming a C2 dimer. In addition, we also discuss several kinds of carbon interstitial defects, and predict that the carbon trimer configuration may be a transition state for a carbon dimer diffusion in Th C.展开更多
High entropy bulk metallic glasses show promising mechanical and physical properties.Dynamic mechanical properties of Ti_（16.7）Zr_（16.7）Hf_（16.7）Cu_（16.7）Ni_（16.7）Be_（16.7）high entropy bulk metallic glass ...High entropy bulk metallic glasses show promising mechanical and physical properties.Dynamic mechanical properties of Ti_（16.7）Zr_（16.7）Hf_（16.7）Cu_（16.7）Ni_（16.7）Be_（16.7）high entropy bulk metallic glass were investigated by mechanical spectroscopy（or called dynamic mechanical analysis）.The main（α）relaxation was observed in the framework of the loss modulus G″,which is related to the dynamic glass transition behaviour for the glassy materials.From physical model point of view,dynamic mechanical properties of the Ti_（16.7）Zr_（16.7）Hf_（16.7）Cu_（16.7）Ni_（16.7）Be_（16.7）high entropy bulk metallic glass show good agreement compared with the quasi-point defects theory.展开更多
Excitation power and temperature-dependent photoluminescence（PL） spectra of the ZnTe epilayer grown on（100）Ga As substrate and ZnTe bulk crystal are investigated. The measurement results show that both the structu...Excitation power and temperature-dependent photoluminescence（PL） spectra of the ZnTe epilayer grown on（100）Ga As substrate and ZnTe bulk crystal are investigated. The measurement results show that both the structures are of good structural quality due to their sharp bound excitonic emissions and absence of the deep level structural defect-related emissions. Furthermore, in contrast to the ZnTe bulk crystal, although excitonic emissions for the ZnTe epilayer are somewhat weak, perhaps due to As atoms diffusing from the Ga As substrate into the ZnTe epilayer and/or because of the strain-induced degradation of the crystalline quality of the ZnTe epilayer, neither the donor–acceptor pair（DAP） nor conduction band-acceptor（e–A） emissions are observed in the ZnTe epilayer. This indicates that by further optimizing the growth process it is possible to obtain a high-crystalline quality ZnTe heteroepitaxial layer that is comparable to the ZnTe bulk crystal.展开更多
基金supported by the National Natural Science Foundation of China(No.52275528)the Hefei Municipal Natural Science Foundation(No.2022018)+1 种基金the Open Foundation of Key Laboratory of High-Power Laser and Physics,Chinese Academy of Sciences(No.SGKF202108)the China Scholarship Council(No.202206695004)。
文摘Fabrication of high-quality optics puts a strong demand on high-throughput detection of macroscopic bulk defects in optical components.A dark-field line confocal imaging method is proposed with two distinct advantages:(ⅰ)a point-to-line confocal scheme formed by a columnar elliptical mirror and an optical fiber bundle breaks through the constraint on light collection angle and field of view in the traditional line confocal microscopy using an objective,allowing for an extended confocal line field of more than 100 mm while maintaining a light collection angle of 27°;(ⅱ)the bulk defects are independently illuminated as a function of time to eliminate the cross talk in the direction of the confocal slit,thus preserving point confocality and showing the optical section thicknesses to be 162μm in the axial direction,and 19 and 22μm in the orthogonal transverse directions.The experimental results verify that the method has a minimum detectable bulk defect of less than 5μm and an imaging efficiency of 400 mm2/s.The method shows great potential in high-throughput and highsensitivity bulk defects detection.
基金Supported by the Hebei Provincial Young Top-Notch Talent Support Program under Grant No BJRC2016the Innovative Funding Project of Graduates of Hebei University under Grant No hbu2018ss62the Midwest Universities Comprehensive Strength Promotion Project
文摘Using the first-principles method, we investigate the thermal stability of cation point defects in LaAlO3 bulk and films. The calculated densities of states indicate that cation vacancies and antisites act as acceptors. The formation energies show that cation vacancies are energetically favorable in bulk LaAIO3 under O-rich conditions, while the AILa antisites are stable in reducing atmosphere. However, the same behavior does not appear in the case of LaAlO3 films. For LaO-terminated LaAlOa fihns, La or AI vacancies remain energetically favorable under O-rich and O-deficient conditions. For an AlO2-terminated surface, under O-rich condition the La interstitial atom is repelled from the outmost layer after optimization, which releases more stress leading to the decrease of total energy of the system. An AI interstitial atom has a smaller radius so that it can stay in distorted films and becomes more stable under O-deficient conditions, and the Al interstitial atoms can be another possible carrier source contribution to the conductivity of n-type interface under an ultrahigh vacuum. La and Al antisites have similar formation energy regardless of oxygen pressure. The results would be helpful to understand the defect structures of LaAlOa-related materials.
基金supported by the National Key Research and Development Program of China(2021YFB3800103)the Fundamental Research Funds for the Central Universities(000-0903069032)the National Natural Science Foundation of China(52203237).
文摘Here,we report a mixed GAI and MAI(MGM)treatment method by forming a 2D alternating-cation-interlayer(ACI)phase(n=2)perovskite layer on the 3D perovskite,modulating the bulk and interfacial defects in the perovskite films simultaneously,leading to the suppressed nonradiative recombination,longer lifetime,higher mobility,and reduced trap density.Consequently,the devices’performance is enhanced to 24.5%and 18.7%for 0.12 and 64 cm^(2),respectively.In addition,the MGM treatment can be applied to a wide range of perovskite compositions,including MA-,FA-,MAFA-,and CsFAMA-based lead halide perovskites,making it a general method for preparing efficient perovskite solar cells.Without encapsulation,the treated devices show improved stabilities.
基金Project supported by the International S&T Cooperation Program of China(Grant No.2014DFG60230)the National Natural Science Foundation of China(Grant No.91326105)+1 种基金the National Basic Research Program of China(Grant No.2010CB934504)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA02040104)
文摘The elastic properties and point defects of thorium monocarbide（ThC） have been studied by means of density functional theory based on the projector-augmented-wave method. The calculated electronic and elastic properties of ThC are in good agreement with experimental data and previous theoretical results. Five types of point defects have been considered in our study, including the vacancy defect, interstitial defect, antisite defect, schottky defect, and composition-conserving defect. Among these defects, the carbon vacancy defect has the lowest formation energy of 0.29 eV. The second most stable defect（0.49 eV） is one of composition-conserving defects in which one carbon is removed to another carbon site forming a C2 dimer. In addition, we also discuss several kinds of carbon interstitial defects, and predict that the carbon trimer configuration may be a transition state for a carbon dimer diffusion in Th C.
基金Item Sponsored by National Natural Science Foundation of China(51401192,51301136)Fundamental Research Funds for the Central Universities of China(3102015ZY027,3102015BJ(Ⅱ)JGZ019)+2 种基金Aerospace Technology Foundation of China(N2014KC0068,2015ZF53072)Space Technology Foundation of China(N2014KC0073)Project of State Key Laboratory of Materials Processing and Die & Mould Technology,Huazhong University of Science and Technology(P2016-12)
文摘High entropy bulk metallic glasses show promising mechanical and physical properties.Dynamic mechanical properties of Ti_（16.7）Zr_（16.7）Hf_（16.7）Cu_（16.7）Ni_（16.7）Be_（16.7）high entropy bulk metallic glass were investigated by mechanical spectroscopy（or called dynamic mechanical analysis）.The main（α）relaxation was observed in the framework of the loss modulus G″,which is related to the dynamic glass transition behaviour for the glassy materials.From physical model point of view,dynamic mechanical properties of the Ti_（16.7）Zr_（16.7）Hf_（16.7）Cu_（16.7）Ni_（16.7）Be_（16.7）high entropy bulk metallic glass show good agreement compared with the quasi-point defects theory.
基金Project supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120131110006)the Key Science and Technology Program of Shandong Province+10 种基金China(Grant No.2013GGX10221)the Key Laboratory of Functional Crystal Materials and Device(Shandong UniversityMinistry of Education)China(Grant No.JG1401)the National Natural Science Foundation of China(Grant No.61306113)the Major Research Plan of the National Natural Science Foundation of China(Grant No.91433112)the Partnership Project for Fundamental Technology Researches of the Ministry of EducationCultureSportsScience and TechnologyJapan
文摘Excitation power and temperature-dependent photoluminescence（PL） spectra of the ZnTe epilayer grown on（100）Ga As substrate and ZnTe bulk crystal are investigated. The measurement results show that both the structures are of good structural quality due to their sharp bound excitonic emissions and absence of the deep level structural defect-related emissions. Furthermore, in contrast to the ZnTe bulk crystal, although excitonic emissions for the ZnTe epilayer are somewhat weak, perhaps due to As atoms diffusing from the Ga As substrate into the ZnTe epilayer and/or because of the strain-induced degradation of the crystalline quality of the ZnTe epilayer, neither the donor–acceptor pair（DAP） nor conduction band-acceptor（e–A） emissions are observed in the ZnTe epilayer. This indicates that by further optimizing the growth process it is possible to obtain a high-crystalline quality ZnTe heteroepitaxial layer that is comparable to the ZnTe bulk crystal.
