Several parameters of a commercial Si-based Schottky barrier diode (SBD) with unknown metal material and semiconductor-type have been investigated in this work from dark forward and reverse I-V characteristics in the ...Several parameters of a commercial Si-based Schottky barrier diode (SBD) with unknown metal material and semiconductor-type have been investigated in this work from dark forward and reverse I-V characteristics in the temperature (T) range of [274.5 K - 366.5 K]. Those parameters include the reverse saturation current (I<sub>s</sub>), the ideality factor (n), the series and the shunt resistances (R<sub>s</sub> and R<sub>sh</sub>), the effective and the zero bias barrier heights (Φ<sub>B</sub> and Φ<sub>B0</sub>), the product of the electrical active area (A) and the effective Richardson constant (A**), the built-in potential (V<sub>bi</sub>), together with the semiconductor doping concentration (N<sub>A</sub> or N<sub>D</sub>). Some of them have been extracted by using two or three different methods. The main features of each approach have been clearly stated. From one parameter to another, results have been discussed in terms of structure performance, comparison on one another when extracted from different methods, accordance or discordance with data from other works, and parameter’s temperature or voltage dependence. A comparison of results on Φ<sub>B</sub>, ΦB0</sub>, n and N<sub>A</sub> or N<sub>D</sub> parameters with some available data in literature for the same parameters, has especially led to clear propositions on the identity of the analyzed SBD’s metal and semiconductor-type.展开更多
BiVO_(4) scheelite is one of the few tetrahedra-based structures able to display vacancy-mediated oxide-ion conduction upon the use of an acceptor-doping strategy,leading to oxide-ion migration.In order to modulate th...BiVO_(4) scheelite is one of the few tetrahedra-based structures able to display vacancy-mediated oxide-ion conduction upon the use of an acceptor-doping strategy,leading to oxide-ion migration.In order to modulate the ionic migration process,it is of utmost importance to understand the different parameters affecting it.Here we review phase formation,oxygen vacancy stabilization,and migration for a wide variety of acceptor metal dopants in scheelite BiVO_(4).Among them,Ca^(2+)-doped materials present the widest solid-solution range,leading to optimized oxide-ion conductivities at moderately high temperatures(σb:∼10-3 S cm^(-1) at 500°C),mainly as a result of their smaller size mismatch with Bi3+and lower oxygen vacancy defect energy.The results gathered herein provide a useful guide for designing new oxide-ion conductors and tailoring oxide conductivity through the proper selection of doping agents according to several criteria,such as the oxygen defect formation energy,atom size mismatch,polarizability,and bond-dissociation energy with oxygen.展开更多
In this work,a one step solvothermal method was used to synthesize uniform anisotropic hexagonal and cylindrical hematite nanoplates in the presence of methanol and ethylene di-amine.The phase and morphology of the sa...In this work,a one step solvothermal method was used to synthesize uniform anisotropic hexagonal and cylindrical hematite nanoplates in the presence of methanol and ethylene di-amine.The phase and morphology of the samples were confirmed by X-ray diffraction(XRD)and electron microscopy.Photocatalytic degradation of methylene blue(MB)was carried out using two different hematite nanoplates to compare their catalytic performance.A systematic study of different parameters affecting the photodegradation of MB was performed.Hexagonal nanoplates exposing(110),(102)and(104)facets exhibit enhanced photocatalytic activity compared to the cylindrical nanoplates that expose only(110)and(102)facets,confirming that the high catalytic activity of the hexagonal nanoplates is attributed to the exposure of more catalytically active facets.展开更多
this paper,we base our analysis on the assumption that the existence of a photon sphere is an intrinsic characteristic of any ultra-compact gravitational structure with spherical symmetry.Utilizing the concept of a to...this paper,we base our analysis on the assumption that the existence of a photon sphere is an intrinsic characteristic of any ultra-compact gravitational structure with spherical symmetry.Utilizing the concept of a topological photon sphere,we categorize the behaviors of various gravitational models based on the structure of their photon spheres.This innovative approach enables us to define boundaries for black hole parameters,subsequently enabling us to classify the model as either a black hole or naked singularity.We demonstrate that the presence of this interplay between the gravitational structure and the existence of a photon sphere is a unique advantage that can be utilized from both perspectives.Our observations indicate that a gravitational model typically exhibits the behavior ofa horizonless structure(or naked singularity)when a minimum effective potential(a stable photon sphere)appears within the studied spacetime region.Additionally,in this study,we investigate the effect of this structure on the behavior of the photon sphere by selecting models that are affected by Perfect Fluid Dark Matter(PFDM).Finally,by analyzing a model with multiple event horizons,we show that the proposed method remains applicable evenin suchscenarios.展开更多
Absorption cooling technology is an environmentally friendly method to generate continuous chilled water making use of multiple thermal sources,such as waste heat and renewable thermal energy.In this study,two absorpt...Absorption cooling technology is an environmentally friendly method to generate continuous chilled water making use of multiple thermal sources,such as waste heat and renewable thermal energy.In this study,two absorption chillers(nominal capacity of 400 kW)with series and parallel connections are evaluated.To research the ideal configuration of chillers after thermodynamic analysis,the structures of the chillers are optimized using the particle swarm optimization algorithm by considering the heat transfer area(HTA),exergy efficiency and total annual cost as single-objective functions.The impact of temperature differences between external and internal flows,heat exchanger efficiencies and the solution allocation ratio is estimated.The optimized HTA,coefficient of perform-ance,exergy efficiency and total annual cost are 149.0 m^(2),1.56,29.44%and$229119 for the series-connected chiller,and 146.7 m^(2),1.59,31.45%and$234562 for the parallel-connected type,respectively.Under the lowest HTA condition,compared with the reference simulation results,the energy and exergy performances are improved,while the annual total cost is higher.The annual total cost is highest when maximizing the exergy efficiency,which is attributed to the increase in the HTA.The operating cost accounts for 27.42%(series type)and 26.54%(parallel type)when the annual cost is the lowest.展开更多
文摘Several parameters of a commercial Si-based Schottky barrier diode (SBD) with unknown metal material and semiconductor-type have been investigated in this work from dark forward and reverse I-V characteristics in the temperature (T) range of [274.5 K - 366.5 K]. Those parameters include the reverse saturation current (I<sub>s</sub>), the ideality factor (n), the series and the shunt resistances (R<sub>s</sub> and R<sub>sh</sub>), the effective and the zero bias barrier heights (Φ<sub>B</sub> and Φ<sub>B0</sub>), the product of the electrical active area (A) and the effective Richardson constant (A**), the built-in potential (V<sub>bi</sub>), together with the semiconductor doping concentration (N<sub>A</sub> or N<sub>D</sub>). Some of them have been extracted by using two or three different methods. The main features of each approach have been clearly stated. From one parameter to another, results have been discussed in terms of structure performance, comparison on one another when extracted from different methods, accordance or discordance with data from other works, and parameter’s temperature or voltage dependence. A comparison of results on Φ<sub>B</sub>, ΦB0</sub>, n and N<sub>A</sub> or N<sub>D</sub> parameters with some available data in literature for the same parameters, has especially led to clear propositions on the identity of the analyzed SBD’s metal and semiconductor-type.
基金The National Natural Science Foundation of China(no.21850410458 and 22005073)Guangxi Natural Science Foundation(no.2019GXNSFBA245010,2020GXNSFAA297050,and 2019GXNSFGA245006)Open Foundation of Key Laboratory of New Processing Technology for Nonferrous Metal&Materials,Ministry of Education/Guangxi Key Laboratory of Optical and Electronic Materials and Devices(20AA-1)are acknowledged for financial support.The DFT calculation work in this research was carried out at the Shanxi Supercomputing Center,and the calculations were performed on TianHe-2.
文摘BiVO_(4) scheelite is one of the few tetrahedra-based structures able to display vacancy-mediated oxide-ion conduction upon the use of an acceptor-doping strategy,leading to oxide-ion migration.In order to modulate the ionic migration process,it is of utmost importance to understand the different parameters affecting it.Here we review phase formation,oxygen vacancy stabilization,and migration for a wide variety of acceptor metal dopants in scheelite BiVO_(4).Among them,Ca^(2+)-doped materials present the widest solid-solution range,leading to optimized oxide-ion conductivities at moderately high temperatures(σb:∼10-3 S cm^(-1) at 500°C),mainly as a result of their smaller size mismatch with Bi3+and lower oxygen vacancy defect energy.The results gathered herein provide a useful guide for designing new oxide-ion conductors and tailoring oxide conductivity through the proper selection of doping agents according to several criteria,such as the oxygen defect formation energy,atom size mismatch,polarizability,and bond-dissociation energy with oxygen.
基金supported by the NSFC(51125001,51172005)Beijing Natural Science Foundation(2122022)+2 种基金NSFC-RGC Joint Research Scheme(51361165201)Doctoral Program of the Ministry of Education of China(20120001110078)the Interdisciplinary Project of Beijing New Star Plan of Science and Technology.
文摘In this work,a one step solvothermal method was used to synthesize uniform anisotropic hexagonal and cylindrical hematite nanoplates in the presence of methanol and ethylene di-amine.The phase and morphology of the samples were confirmed by X-ray diffraction(XRD)and electron microscopy.Photocatalytic degradation of methylene blue(MB)was carried out using two different hematite nanoplates to compare their catalytic performance.A systematic study of different parameters affecting the photodegradation of MB was performed.Hexagonal nanoplates exposing(110),(102)and(104)facets exhibit enhanced photocatalytic activity compared to the cylindrical nanoplates that expose only(110)and(102)facets,confirming that the high catalytic activity of the hexagonal nanoplates is attributed to the exposure of more catalytically active facets.
文摘this paper,we base our analysis on the assumption that the existence of a photon sphere is an intrinsic characteristic of any ultra-compact gravitational structure with spherical symmetry.Utilizing the concept of a topological photon sphere,we categorize the behaviors of various gravitational models based on the structure of their photon spheres.This innovative approach enables us to define boundaries for black hole parameters,subsequently enabling us to classify the model as either a black hole or naked singularity.We demonstrate that the presence of this interplay between the gravitational structure and the existence of a photon sphere is a unique advantage that can be utilized from both perspectives.Our observations indicate that a gravitational model typically exhibits the behavior ofa horizonless structure(or naked singularity)when a minimum effective potential(a stable photon sphere)appears within the studied spacetime region.Additionally,in this study,we investigate the effect of this structure on the behavior of the photon sphere by selecting models that are affected by Perfect Fluid Dark Matter(PFDM).Finally,by analyzing a model with multiple event horizons,we show that the proposed method remains applicable evenin suchscenarios.
基金supported by National Natural Science Foundation of China(grant no.51736006).
文摘Absorption cooling technology is an environmentally friendly method to generate continuous chilled water making use of multiple thermal sources,such as waste heat and renewable thermal energy.In this study,two absorption chillers(nominal capacity of 400 kW)with series and parallel connections are evaluated.To research the ideal configuration of chillers after thermodynamic analysis,the structures of the chillers are optimized using the particle swarm optimization algorithm by considering the heat transfer area(HTA),exergy efficiency and total annual cost as single-objective functions.The impact of temperature differences between external and internal flows,heat exchanger efficiencies and the solution allocation ratio is estimated.The optimized HTA,coefficient of perform-ance,exergy efficiency and total annual cost are 149.0 m^(2),1.56,29.44%and$229119 for the series-connected chiller,and 146.7 m^(2),1.59,31.45%and$234562 for the parallel-connected type,respectively.Under the lowest HTA condition,compared with the reference simulation results,the energy and exergy performances are improved,while the annual total cost is higher.The annual total cost is highest when maximizing the exergy efficiency,which is attributed to the increase in the HTA.The operating cost accounts for 27.42%(series type)and 26.54%(parallel type)when the annual cost is the lowest.
