Thallium is a heavy metal highly toxic to the biosphere. It can be determined by anodic stripping voltammetry after deposition on mercury film. The aim of this work is to study the conditions and mechanisms of deposit...Thallium is a heavy metal highly toxic to the biosphere. It can be determined by anodic stripping voltammetry after deposition on mercury film. The aim of this work is to study the conditions and mechanisms of deposition of Hg on glassy carbon electrode and Tl on Hg film by cyclic voltammetry, scanning electron microscopy, chronoamperometry and impedance techniques. The results showed a germination and growth of a 3D Hg phase on glassy carbon electrode. Similarly, the electrodeposition of Tl on Hg follows a 3D three-dimensional nucleation with diffusion controlled growth. The impedance measurements reveal an easier charge transfer on the Tl film.展开更多
Using the extensively studied V_(2)O_(3) as a prototype system, we investigate the role of percolation in metal-insulator transition(MIT). We apply scanning microwave impedance microscopy to directly determine the met...Using the extensively studied V_(2)O_(3) as a prototype system, we investigate the role of percolation in metal-insulator transition(MIT). We apply scanning microwave impedance microscopy to directly determine the metallic phase fraction p and relate it to the macroscopic conductance G, which shows a sudden jump when p reaches the percolation threshold. Interestingly, the conductance G exhibits a hysteretic behavior against p, suggesting two different percolating processes upon cooling and warming. Based on our image analysis and model simulation, we ascribe such hysteretic behavior to different domain nucleation and growth processes between cooling and warming, which is likely caused by the decoupled structural and electronic transitions in V_(2)O_(3) during MIT. Our work provides a microscopic view of how the interplay of structural and electronic degrees of freedom affects MIT in strongly correlated systems.展开更多
The influence of sodium silicate on the corrosion behaviour of aluminium alloy 7075-T6 in 0.1 M sodium chloride solution was studied by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tec...The influence of sodium silicate on the corrosion behaviour of aluminium alloy 7075-T6 in 0.1 M sodium chloride solution was studied by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) techniques. Scanning electron microscopy (SEM) was used to characterize the AA7075-T6 surface. Silicate can significantly reduce corrosion deterioration and the inhibition efficiency increases with the concentration of Na<sub>2</sub>SiO<sub>3</sub>. The corrosion inhibition mechanism involves the formation of a protective film over the alloy surface by adsorption of aluminosilicate anions from solution, as has also been suggested by others in literature.展开更多
文中基于安装在扫描电子显微镜(Scanning Electron Microscopy, SEM)中的纳米操作机,对具有微米级细晶粒的氧化锌(ZnO)压电陶瓷进行了单晶粒边界的直接电学测量。由纳米操作机操纵的双探针作为微电极夹在机械手上,测量了ZnO压电陶瓷晶...文中基于安装在扫描电子显微镜(Scanning Electron Microscopy, SEM)中的纳米操作机,对具有微米级细晶粒的氧化锌(ZnO)压电陶瓷进行了单晶粒边界的直接电学测量。由纳米操作机操纵的双探针作为微电极夹在机械手上,测量了ZnO压电陶瓷晶界的伏安特性曲线、非线性系数以及20个晶粒的平均尺寸。在20 Hz~1 MHz的频率范围内,通过等效电路拟合,以阻抗复平面表示实验数据。实验表明低频直流高阻阻抗的本质可归因于晶界,同时20 Hz下的电阻分布可用于预测ZnO压电陶瓷在某些较低频率下的阻抗特性。展开更多
文摘Thallium is a heavy metal highly toxic to the biosphere. It can be determined by anodic stripping voltammetry after deposition on mercury film. The aim of this work is to study the conditions and mechanisms of deposition of Hg on glassy carbon electrode and Tl on Hg film by cyclic voltammetry, scanning electron microscopy, chronoamperometry and impedance techniques. The results showed a germination and growth of a 3D Hg phase on glassy carbon electrode. Similarly, the electrodeposition of Tl on Hg follows a 3D three-dimensional nucleation with diffusion controlled growth. The impedance measurements reveal an easier charge transfer on the Tl film.
基金Fudan University was supported by the National Natural Science Foundation of China (Grant Nos. 12074080, 11804052, 11827805,11725521, and 12035004)the National Postdoctoral Program for Innovative Talents (Grant No. BX20180079)+5 种基金the Shanghai Science and Technology Committee Rising-Star Program (Grant No. 19QA1401000)the Science and Technology Commission of Shanghai Municipality (Grant No.20JC1414700)the Major Project (Grant No. 2019SHZDZX01)the Ministry of Science and Technology of China (Grant Nos. 2017YFA03030002021YFA1400100)(synthesis, structural characterization and global transport of V2O3) at University of California San Diego was supported by the US Air Force Office of Scientific Research (Grant No.FA9550-20-1-0242)。
文摘Using the extensively studied V_(2)O_(3) as a prototype system, we investigate the role of percolation in metal-insulator transition(MIT). We apply scanning microwave impedance microscopy to directly determine the metallic phase fraction p and relate it to the macroscopic conductance G, which shows a sudden jump when p reaches the percolation threshold. Interestingly, the conductance G exhibits a hysteretic behavior against p, suggesting two different percolating processes upon cooling and warming. Based on our image analysis and model simulation, we ascribe such hysteretic behavior to different domain nucleation and growth processes between cooling and warming, which is likely caused by the decoupled structural and electronic transitions in V_(2)O_(3) during MIT. Our work provides a microscopic view of how the interplay of structural and electronic degrees of freedom affects MIT in strongly correlated systems.
文摘The influence of sodium silicate on the corrosion behaviour of aluminium alloy 7075-T6 in 0.1 M sodium chloride solution was studied by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) techniques. Scanning electron microscopy (SEM) was used to characterize the AA7075-T6 surface. Silicate can significantly reduce corrosion deterioration and the inhibition efficiency increases with the concentration of Na<sub>2</sub>SiO<sub>3</sub>. The corrosion inhibition mechanism involves the formation of a protective film over the alloy surface by adsorption of aluminosilicate anions from solution, as has also been suggested by others in literature.
