Experimental Study of the Relative Energy of Symmetrical Tilt Boundaries in a Semi-Conducting F.C.C. Oxide (NiO).

1981 ◽  
Vol 5 ◽  
Author(s):  
Guy Dhalenne ◽  
Michel Dechamps ◽  
Alexandre Revcolevschi
Keyword(s):  
Experimental Study ◽  
Grain Boundary ◽  
Interface Energy ◽  
Relative Energy ◽  
Energy Curve ◽  
Fusion Technique ◽  
Large Size ◽  
Tilt Boundaries ◽  
Misorientation Angles

ABSTRACTLarge size bicrystalline samples of NiO corresponding to tilt configurations around a < 110 > axis have been grown by the flame fusion technique, the misorientation angles varying from 0 to 180°. The variation of the relative energy of the grain boundary with misorientation has been studied and has indicated a very different behaviour from that previously observed by the authors on <100> tilt boundaries. High relative energy values and deep cusps on the energy curve at high coincidence angles are observed. The results are discussed in terms of interface energy.

Effect of Grain Boundary Geometry on Grain Rotation during Curvature-Driven Grain Shrinkage

2016 ◽  
Vol 9 ◽  
pp. 73-81 ◽  
Author(s):  
L.A. Barrales-Mora ◽  
Jann Erik Brandenburg ◽  
Dmitri A. Molodov
Keyword(s):  
Grain Boundary ◽  
Screw Dislocations ◽  
Grain Rotation ◽  
Tilt Boundaries ◽  
Boundary Geometry ◽  
Dynamics Simulations ◽  
Curvature Driven ◽  
Edge Dislocations ◽  
Misorientation Angles ◽  
Twist Boundaries

Molecular dynamics simulations were performed to analyze the curvature-driven shrinkage of individual cylindrical grains with geometrically different boundaries in Al. Grains with <100> tilt and mixed tilt-twist boundaries with the misorientations 5.5°, 16.3°, and 22.6° were simulated. The results revealed that the shrinking grains with tilt boundaries concurrently rotate increasing the misorientation angles, whereas grains with the mixed boundaries did not rotate during their shrinkage. Apparently, the grain boundary geometry/structure has a crucial impact on the observed rotational behavior of the computed grains. The grains with tilt boundaries rotate due to the lack of effectively operating mechanisms for annihilation of edge dislocations, which compose such boundaries. In contrast, for the mixed boundaries composed of edge-screw dislocations the sufficiently fast operating mechanisms of dislocation elimination are available, which facilitates grain shrinkage without rotation.

Effect of thermal annealing on grain boundary chemistry of polycrystalline TiBa2Ca2Cu3Oy films

1994 ◽  
Vol 52 ◽  
pp. 968-969
Author(s):  
Z. L. Wang ◽  
C. L. Briant ◽  
J. DeLuca ◽  
A. Goyal ◽  
D. M. Kroeger ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Weak Link ◽  
Zero Field ◽  
Stabilized Zirconia ◽  
Local Texture ◽  
Transmission Electron ◽  
Axis Alignment ◽  
Boundary Chemistry ◽  
Small Misorientation ◽  
Misorientation Angles

Recent studies have shown that spray-pyrolyzed films of the Tl-1223 compound (TlxBa2Ca2Cu3Oy, with 0.7 < × < 0.95) on polycrystalline yttrium stabilized zirconia substrates can be prepared which have critical current density Jc near 105 A/cm2 at 77 K, in zero field. The films are polycrystalline, have excellent c-axis alignment, and show little evidence of weak-link behavior. Transmission electron microscopy (TEM) studies have shown that most grain boundaries have small misorientation angles. It has been found that the films have a nigh degree of local texture indicative of colonies of similarly oriented grains. It is believed that inter-colony conduction is enhanced by a percolative network of small angle boundaries at colony interfaces. It has also been found that Jc is increased by a factor of 4 - 5 after the films were annealed at 600 °C in oxygen. This study is thus carried out to determine the effect on grain boundary chemistry of the heat treatment.

Characterization of Tilt Boundaries by Ultra High Resolution Electron Microscopy

1984 ◽  
Vol 41 ◽  
Author(s):  
W. Krakow ◽  
J. T. Wetzel ◽  
D. A. Smith ◽  
G. Trafas
Keyword(s):  
High Resolution ◽  
Grain Boundary ◽  
Structural Information ◽  
Theoretical Work ◽  
High Resolution Electron Microscopy ◽  
Point Of View ◽  
Experimental Point ◽  
Structure Information ◽  
Resolution Electron ◽  
Tilt Boundaries

AbstractA high resolution electron microscope study of grain boundary structures in Au thin films has been undertaken from both a theoretical and experimental point of view. The criteria necessary to interpret images of tilt boundaries at the atomic level, which include electron optical and specimen effects, have been considered for both 200kV and the newer 400kV medium voltage microscopes. So far, the theoretical work has concentrated on two different [001] tilt bounda-ries where a resolution of 2.03Å is required to visualize bulk lattice structures on either side of the interface. Both a high angle boundary, (210) σ=5, and a low angle boundary, (910) σ=41, have been considered. Computational results using multislice dynamical diffraction and image simulations of relaxed bounda-ries viewed edge-on and with small amounts of beam and/or specimen inclina-tion have been obtained. It will be shown that some structural information concerning grain boundary dislocations can be observed at 200kV. However, many difficulties occur in the exact identification of the interface structure viewed experimentally for both [001] and [011] boundaries since the resolution required is near the performance limit of a 200kV microscope. The simulated results at 400kV indicate a considerable improvement will be realized in obtain-ing atomic structure information at the interface.

Microstructures of a-axis oriented YBCO films made by hybrid plasma sputtering

1995 ◽  
Vol 10 (4) ◽  
pp. 803-809 ◽  
Author(s):  
W. Ito ◽  
A. Oishi ◽  
S. Mahajan ◽  
Y. Yoshida ◽  
T. Morishita
Keyword(s):  
Electron Microscopy ◽  
Grain Boundary ◽  
Anisotropic Growth ◽  
Plan View ◽  
Plasma Sputtering ◽  
Transmission Electron ◽  
Hybrid Plasma ◽  
Tilt Boundaries ◽  
Symmetrical Tilt ◽  
Twist Boundaries

Microstructures of a-axis oriented YBa2Cu3O7−x films made by newly developed de 100 MHz hybrid plasma sputtering were investigated using transmission electron microscopy (TEM). The films deposited on (110) NdGaO3 and (100) SrTiO3 substrates were found to grow in a perfect epitaxial fashion and with clear interface. The plan view of the TEM image showed that both films were comprised of two kinds of grains having the c axis aligning along two perpendicular directions in the plane with equal probability. The structures of the grain boundary, however, were found to be very different for the two films from the plan views. The film on NdGaO3 showed a lot of twist boundaries, while the film on SrTiO3 consisted of many symmetrical tilt boundaries and basal-plane-faced tilt boundaries. The type of grain boundary is determined by the anisotropic growth rates of the film between c direction and a-b direction.

A Numerical and Experimental Study of Cavitation in a Hot Tensile Axisymmetric Testpiece

2005 ◽  
Vol 40 (6) ◽  
pp. 571-586 ◽  
Author(s):  
Y Liu ◽  
J Lin ◽  
T. A Dean ◽  
D. C. J Farrugia
Keyword(s):  
Experimental Study ◽  
Flow Stress ◽  
Grain Boundary ◽  
Thermal Gradient ◽  
Tensile Testing ◽  
Tensile Deformation ◽  
Strain Rates ◽  
Test Results ◽  
Integrated Technique ◽  
Hot Tensile Deformation

During axisymmetric hot tensile testing, necking normally takes place due to the thermal gradient and the accumulation of microdamage. This paper introduces an integrated technique to predict the damage and necking evolution behaviour. Firstly, a set of multiaxial mechanism-based unified viscoplastic-damage constitutive equations is presented. This equation set, which models the evolution of grain boundary (intragranular) and plasticity-induced (intergranular) damage, is determined for a free-cutting steel tested over a range of temperatures and strain rates on a Gleeble thermomechanical simulator. This model has been implemented using the CREEP subroutine of the commercial finite element (FE) solver ABAQUS. Numerical procedures to simulate axisymmetric hot tensile deformation are developed with consideration of the thermal gradient along the axis of the tensile testpiece. FE simulations are carried out to reproduce the necking phenomenon and the evolution of plasticity-induced and grain boundary damage. The simulated results have been validated with experimental tensile test results. The effects of necking and its associated stress state on flow stress and ductility are investigated. The flow stress and ductility data obtained from a Gleeble material simulator under various hot deformation conditions have also been numerically studied.

Experimental Study of Thermal Effect on Large Size Nd:YAG Side Pumped Thin Disk Laser

Applied laser ◽  
2011 ◽  
Vol 31 (5) ◽  
pp. 414-417
Author(s):  
冯驰 Feng Chi ◽  
郭渭荣 Guo Weirong ◽  
李强 Li Qiang
Keyword(s):  
Experimental Study ◽  
Thermal Effect ◽  
Thin Disk ◽  
Disk Laser ◽  
Large Size ◽  
Thin Disk Laser

scholarly journals First-Principles Study of the Impact of Grain Boundary Formation in the Cathode Material LiFePO4

2019 ◽  
Vol 4 (3) ◽  
pp. 80 ◽  
Author(s):  
Jan Kuriplach ◽  
Aki Pulkkinen ◽  
Bernardo Barbiellini
Keyword(s):  
Grain Boundary ◽  
Cathode Material ◽  
First Principles ◽  
Magnetic Moments ◽  
Lithium Ion ◽  
Coincident Site Lattice ◽  
Interface Energy ◽  
First Principles Study ◽  
Lifepo4 Cathode ◽  
The Impact

Motivated by the need to understand the role of internal interfaces in Li migration occurring in lithium-ion batteries, a first-principles study of a coincident site lattice grain boundary in LiFePO4 cathode material and in its delithiated counterpart FPO4 is performed. The structure of the investigated grain boundary is obtained, and the corresponding interface energy is calculated. Other properties, such as ionic charges, magnetic moments, excess free volume, and the lifetime of positrons trapped at the interfaces are determined and discussed. The results show that while the grain boundary in LiFePO4 has desired structural and bonding characteristics, the analogous boundary in FePO4 needs to be yet optimized to allow for an efficient Li diffusion study.

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