Grain-Boundary Surface Terminations Incorporating Oxygen Vacancies for Selectively Boosting CO2 Photoreduction Activity

Nanoparticles of yttria-doped tetragonal zirconia polycrystalline ceramics (Y-TZP) with an average crystallite size of less than 9 nm were prepared by a combustion synthesis process. Dense and fine-grained (<200 nm) Y-TZP ceramics were obtained by fast-firing using temperatures lower than 1400 °C and dwell times of less than 2 min. Impedance spectroscopy was employed to measure conductivities of oxygen vacancies in the grain and the grain boundary of the fine-grained Y-TZP. The relationships between the concentration of the oxygen vacancies in the grain boundary and measurable physical parameters were determined semiquantitatively. The oxygen vacancy concentrations and activation energies for the oxygen-ion conduction in the grain and the grain boundary of the fine-grained Y-TZP were found to be independent of the average grain size in the average grain-size range of 90–200 nm. These experimental results suggest that, in order to retain the abnormally high oxygen vacancy concentrations of the Y-TZP nanoparticles and thus enhance the oxygen-ion conductivity, it may be necessary to decrease the average grain size to approximately 10 nm.

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The Effect of Grain Boundaries on Surface Diffusion Mediated-Planarization of Polycrystalline Cu Films

MRS Proceedings ◽

10.1557/proc-389-107 ◽

1995 ◽

Vol 389 ◽

Cited By ~ 3

Author(s):

R.A. Brain ◽

D.S. Gardner ◽

D.B. Fraser ◽

H.A. Atwater

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Surface Diffusion ◽

Cross Sections ◽

Boundary Surface ◽

Surface Profile ◽

Transmission Electron Micrograph ◽

Cu Films ◽

Transmission Electron

ABSTRACTIn situ, ultrahigh vacuum anneals were performed to induce Cu reflow at 500°C following deposition of Cu films and a Ta barrier layer on 1 μm wide by 1 μm deep trenches. Transmission electron micrograph cross-sections show profiles which suggest that grain boundaries and surface energy anisotropy significantly affect reflow. The extent of reflow is dependent on the structure of grain boundary-surface intersections, and the surface profile consists of regions of low curvature within grains and with sharp discontinuities in curvature at grain boundaries, a structure that inhibits surface diffusion. We present results showing how the surface diffusion mediated reflow varies with grain boundary groove angle and position, and compare these results with finite-element simulations that model surface diffusion-driven reflow.

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First-Principles Calculations of Grain Boundary-Surface for Various Grain Boundaries with Different Energies in Aluminum

Materials Science Forum ◽

10.4028/www.scientific.net/msf.551-552.331 ◽

2007 ◽

Vol 551-552 ◽

pp. 331-336 ◽

Cited By ~ 2

Author(s):

Tokuteru Uesugi ◽

Y. Inoue ◽

Yorinobu Takigawa ◽

Kenji Higashi

Keyword(s):

Shear Strength ◽

Grain Boundary ◽

First Principles ◽

Boundary Surface ◽

Grain Boundary Sliding ◽

Excess Energy ◽

First Principles Calculations ◽

Perfect Single Crystal ◽

Boundary Sliding ◽

The Ideal

The grain boundary surface is the excess energy of the grain boundary as the lattice on one side of the grain is translated relative to the lattice on the other side of the grain. The maximum in the slope of the grain boundary surface determines the ideal shear strength for the grain boundary sliding. We presented the ideal shear strength for the grain boundary sliding in aluminum Σ3(11 2)[110] tilt grain boundary from the first-principles calculations. The ideal shear strength for the grain boundary sliding was much smaller than the ideal shear strength of a perfect single crystal.

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The Influence of Grain Boundary Migration on the Diffusion Behaviour of Thin Films

Zeitschrift für Naturforschung A ◽

10.1515/zna-1980-0606 ◽

1980 ◽

Vol 35 (6) ◽

pp. 613-618

Author(s):

E. Ehrmann-Falkenau ◽

A. Wagendristel

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Boundary Migration ◽

Boundary Surface ◽

Depth Profiling ◽

Lattice Diffusion ◽

Grain Boundary Migration ◽

Order Of Magnitude ◽

Diffusion Behaviour

Simultaneous grain boundary-, surface- and lattice diffusion in hypothetical thin film couples of miscible components was computer simulated. On this basis the diffusion into fixed and moving grain boundaries is discussed with respect to the determination of diffusivities by depth profiling methods. The data evaluated from the synthesised depth profiles according to Whipple-Le Claire as well as to Gilmer and Farrell were compared with the diffusivities used for the computation. Agreement was found for systems with a fixed grain boundary network. Moving grain boundaries, however, may cause errors of an order of magnitude towards lower grain boundary diffusivities

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Construction of melamine foam–supported WO3/CsPbBr3 S–scheme heterojunction with rich oxygen vacancies for efficient and long–period CO2 photoreduction in liquid–phase H2O environment

Chemical Engineering Journal ◽

10.1016/j.cej.2021.132820 ◽

2021 ◽

pp. 132820

Author(s):

Yuanyuan Zhang ◽

Linxing Shi ◽

Haoyang Yuan ◽

Xianggang Sun ◽

Xinyi Li ◽

...

Keyword(s):

Liquid Phase ◽

Oxygen Vacancies ◽

Co2 Photoreduction ◽

Long Period ◽

Melamine Foam

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Effects of Trace Pb on Creep and Fracture of 25Cr35Ni-Nb Alloy

Volume 6A: Materials and Fabrication ◽

10.1115/pvp2015-45354 ◽

2015 ◽

Author(s):

Tao Chen ◽

Chen Xuedong ◽

Yunrong Lv ◽

Juan Ye ◽

Xiyun Hao

Keyword(s):

High Temperature ◽

Grain Boundary ◽

Centrifugal Casting ◽

Boundary Surface ◽

Local Stress ◽

Composition Analysis ◽

Early Failure ◽

Creep Properties ◽

Loading Rates ◽

Fractographic Observation

The centrifugal casting 25Cr35Ni-Nb ethylene pyrolysis furnace tubes with different contents of Pb were selected to study the effects of Pb content on the creep and fracture properties. Both the high temperature rupture test at 1100 °C /17 MPa and the slow straining test at 850 °C with different loading rates show that the increase of Pb content significantly degrades the high temperature creep properties of centrifugal casting 25Cr35Ni-Nb alloy furnace tubes. The fractographic observation and the chemical composition analysis show that Pb segregates to the grain boundary at high temperature. It shows that the segregation of Pb to grain boundary occurs even when the content of Pb is several ppm, which leads to the reduction of grain boundary surface energy at high temperature. The initiation of creep cavities becomes easier. The creep cavities coalesce together under the local stress, forming cracks and finally causing the early failure of furnace tubes.

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