The defect distribution across an ultrathin film CdTe layer of a CdS/CdTe solar cell is modelled by solving the balance equation in steady state. The degradation of the device parameters due to the induced defects dur...The defect distribution across an ultrathin film CdTe layer of a CdS/CdTe solar cell is modelled by solving the balance equation in steady state. The degradation of the device parameters due to the induced defects during ion implantation is considered where the degradation rate is accelerated if the defect distribution is considerable.The defect concentration is maximum at the surface of the CdTe layer where implantation is applied and it is minimum at the junction with the CdS layer. It shows that ultrathin devices degrade faster if the defect concentration is high at the junction rather than the back region（CdTe/Metal）. Since the front and back contacts of the device are close in ultrathin films and the electric field is strong to drive the defects into the junction, the p-doping process might be precisely controlled during ion implantation. The modeling results presented here are in agreement with the few available experimental reports in literature about the degradation and defect configuration of the ultrathin CdTe films.展开更多
Our calculations demonstrate that the concentration of neutral oxygen vacancies can affect the geometrical structrue,electronic structure, and optical properties of α-quartz. Moreover, the distribution of the neutral...Our calculations demonstrate that the concentration of neutral oxygen vacancies can affect the geometrical structrue,electronic structure, and optical properties of α-quartz. Moreover, the distribution of the neutral oxygen divacancy can also exert some influence on the properties of α-quartz. The dissimilarity and similarities are presented in the corresponding density of state（DOS） and absorption spectrum. In addition, when a higher defect concentration is involved in α-quartz,the influence of E1 center on the geometry of α-quartz becomes more significant. However, the introduction of an E1 center barely results in any improvement compared with the influence produced by the corresponding neutral defect.展开更多
We introduce a model of redistribution of point radiation defects, their interaction between themselves and redistribution of their simplest complexes（divacancies and diinterstitials） in a multilayer structure. The ...We introduce a model of redistribution of point radiation defects, their interaction between themselves and redistribution of their simplest complexes（divacancies and diinterstitials） in a multilayer structure. The model gives a possibility to describe qualitatively nonmonotonicity of distributions of concentrations of radiation defects on interfaces between layers of the multilayer structure. The nonmonotonicity was recently found experimentally.To take into account the nonmonotonicity we modify recently used in literature model for analysis of distribution of concentration of radiation defects. To analyze the model we used an approach of solution of boundary problems,which could be used without crosslinking of solutions on interfaces between layers of the considered multilayer structures.展开更多
The steel-shell concrete immersed tube(SSIT)with the self-compacting concrete(SCC)has been applied in the Shenzhen–Zhongshan Link,and the SSIT is prone to the void defect during the concrete pouring process.This work...The steel-shell concrete immersed tube(SSIT)with the self-compacting concrete(SCC)has been applied in the Shenzhen–Zhongshan Link,and the SSIT is prone to the void defect during the concrete pouring process.This work aims to study the flow behavior of the SCC and investigate the generation and distribution of the void defect in the SSIT,and the computational fluid dynamics(CFD)models are adopted to solve the above problems.To verify the CFD models,the slump test,L-box test,and field test based on Ok.the impact image method are carried out.The effects of the connecting hole spacing,the exhaust hole number,the exhaust hole position and the pouring speed on the flow behavior and the void defects distribution are quantitatively compared.According to the comparison results,the standard compartment with 300 mm connecting hole spacing and 10 exhaust holes is the optimal compartment structure design,and the concrete pouring speed of 15 m^(3)/h is the optimal construction method.This work demonstrates that the CFD model offers a useful way to evaluate the generation and distribution features of the void defects for the steel–concrete–steel structure.展开更多
Black TiO_(2-x)is an attractive material due to its adjustable band structure,useful in different applications,and has been heavily investigated and developed.The current reduction of TiO_(2)involves a process from su...Black TiO_(2-x)is an attractive material due to its adjustable band structure,useful in different applications,and has been heavily investigated and developed.The current reduction of TiO_(2)involves a process from surface to center:thus,the issue of either insufficient or excessive reduction seems inevitable.To the best of our knowledge,it is rarely reported that a homogeneous defect distribution can be facilely achieved inside black TiO_(2-x).In this study,a bulk-reduced rutile TiO_(2-x)was obtained via a circuitous two-step approach,with an intermediate Magnéli phase(TinO_(2)n-1).With the decomposition of a solid atmosphere creator(e.g.KClO_(4)grains)at a high temperature,the missing oxygen ions in Ti_(4)O_(7)could be replenished quantitatively.The TEM and SAED results reveal that the oxidation process is not just a surface reaction,but it involves reverse displacement or structural rearrangement inside the crystal.In particular,the periodic variation of crystallographic sheer planes was the direct evidence of the above bulk reaction,i.e.unified long period for Ti_(4)O_(7)and varied long period for critical ratio sample.The as-prepared samples showed different band gaps and colors,based on their oxygen content.KClO_(4),with a critical mixing ratio of around 17.5 mol%,could almost oxidize Ti_(4)O_(7)to black rutile TiO_(2-x).Furthermore,the sample formed at the critical ratio showed a considerable photo-thermal response speed of 1.7℃s^(-1) and an equilibrium temperature of up to 70℃under irradiation with light above 400 nm,which can be an evidence for the enhancement of non-intrinsic absorption.In short,this study provides a new route for the controllable preparation of black TiO_(2-x),and a possibility for further development of other solid atmosphere creators.展开更多
基金National Natural Science Foundation of China !under Grant No. 59671039.
文摘The effects of distribution of induced defects on the positron diffusion was studied by using the point-source diffusion model and 6 function method.
文摘The defect distribution across an ultrathin film CdTe layer of a CdS/CdTe solar cell is modelled by solving the balance equation in steady state. The degradation of the device parameters due to the induced defects during ion implantation is considered where the degradation rate is accelerated if the defect distribution is considerable.The defect concentration is maximum at the surface of the CdTe layer where implantation is applied and it is minimum at the junction with the CdS layer. It shows that ultrathin devices degrade faster if the defect concentration is high at the junction rather than the back region（CdTe/Metal）. Since the front and back contacts of the device are close in ultrathin films and the electric field is strong to drive the defects into the junction, the p-doping process might be precisely controlled during ion implantation. The modeling results presented here are in agreement with the few available experimental reports in literature about the degradation and defect configuration of the ultrathin CdTe films.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11176020 and 11374217)the Doctoral Program of Higher Education of China(Grant No.20100181110080)
文摘Our calculations demonstrate that the concentration of neutral oxygen vacancies can affect the geometrical structrue,electronic structure, and optical properties of α-quartz. Moreover, the distribution of the neutral oxygen divacancy can also exert some influence on the properties of α-quartz. The dissimilarity and similarities are presented in the corresponding density of state（DOS） and absorption spectrum. In addition, when a higher defect concentration is involved in α-quartz,the influence of E1 center on the geometry of α-quartz becomes more significant. However, the introduction of an E1 center barely results in any improvement compared with the influence produced by the corresponding neutral defect.
文摘We introduce a model of redistribution of point radiation defects, their interaction between themselves and redistribution of their simplest complexes（divacancies and diinterstitials） in a multilayer structure. The model gives a possibility to describe qualitatively nonmonotonicity of distributions of concentrations of radiation defects on interfaces between layers of the multilayer structure. The nonmonotonicity was recently found experimentally.To take into account the nonmonotonicity we modify recently used in literature model for analysis of distribution of concentration of radiation defects. To analyze the model we used an approach of solution of boundary problems,which could be used without crosslinking of solutions on interfaces between layers of the considered multilayer structures.
基金supported by the R&D Projects in Key Areas of Guangdong Province(No.20191105).
文摘The steel-shell concrete immersed tube(SSIT)with the self-compacting concrete(SCC)has been applied in the Shenzhen–Zhongshan Link,and the SSIT is prone to the void defect during the concrete pouring process.This work aims to study the flow behavior of the SCC and investigate the generation and distribution of the void defect in the SSIT,and the computational fluid dynamics(CFD)models are adopted to solve the above problems.To verify the CFD models,the slump test,L-box test,and field test based on Ok.the impact image method are carried out.The effects of the connecting hole spacing,the exhaust hole number,the exhaust hole position and the pouring speed on the flow behavior and the void defects distribution are quantitatively compared.According to the comparison results,the standard compartment with 300 mm connecting hole spacing and 10 exhaust holes is the optimal compartment structure design,and the concrete pouring speed of 15 m^(3)/h is the optimal construction method.This work demonstrates that the CFD model offers a useful way to evaluate the generation and distribution features of the void defects for the steel–concrete–steel structure.
基金supported by National key research and development program(Grant No.2016YFB0901600)NSF of China(Grant No.21871008,21801247)+2 种基金Science and Technology Commission of Shanghai(Grant No.17ZR1434400,18YF1427200)Innovation Project of Shanghai Institute of Ceramics(Grant No.Y93ZC2120G)sponsored by Shanghai Sailing Program(Grant 18YF1427200).
文摘Black TiO_(2-x)is an attractive material due to its adjustable band structure,useful in different applications,and has been heavily investigated and developed.The current reduction of TiO_(2)involves a process from surface to center:thus,the issue of either insufficient or excessive reduction seems inevitable.To the best of our knowledge,it is rarely reported that a homogeneous defect distribution can be facilely achieved inside black TiO_(2-x).In this study,a bulk-reduced rutile TiO_(2-x)was obtained via a circuitous two-step approach,with an intermediate Magnéli phase(TinO_(2)n-1).With the decomposition of a solid atmosphere creator(e.g.KClO_(4)grains)at a high temperature,the missing oxygen ions in Ti_(4)O_(7)could be replenished quantitatively.The TEM and SAED results reveal that the oxidation process is not just a surface reaction,but it involves reverse displacement or structural rearrangement inside the crystal.In particular,the periodic variation of crystallographic sheer planes was the direct evidence of the above bulk reaction,i.e.unified long period for Ti_(4)O_(7)and varied long period for critical ratio sample.The as-prepared samples showed different band gaps and colors,based on their oxygen content.KClO_(4),with a critical mixing ratio of around 17.5 mol%,could almost oxidize Ti_(4)O_(7)to black rutile TiO_(2-x).Furthermore,the sample formed at the critical ratio showed a considerable photo-thermal response speed of 1.7℃s^(-1) and an equilibrium temperature of up to 70℃under irradiation with light above 400 nm,which can be an evidence for the enhancement of non-intrinsic absorption.In short,this study provides a new route for the controllable preparation of black TiO_(2-x),and a possibility for further development of other solid atmosphere creators.
