The Structure and Stability of Twist Boundaries in SrTiO3 First Principles

2002 ◽  
Vol 718 ◽  
Author(s):  
Roope K. Astala ◽  
Paul D. Bristowe
Keyword(s):  
Grain Boundary ◽  
Experimental Observation ◽  
First Principles ◽  
Chemical Potential ◽  
Computational Method ◽  
Structure And Stability ◽  
Limits Of Stability ◽  
Twist Boundaries

AbstractA first principles density funtional computational method has been used to investigate the atomic stucture and energy of various distinct forms of the σ = 5(001) twist grain boundary in SrTiO3. The study focuses on four non-stoichiometric geometries which are all found to be stable to be the most stable. The grain boundary energies are computed as a function of TiO2 chemical potential and these define the limits of stability. The computed volume expansions are consistent with experimental observation and the in plane relaxations lower the boundary symmetry.

The Properties of a Na-Doped Twist Boundary in SrTiO3 from First Principles

2002 ◽  
Vol 751 ◽  
Author(s):  
Roope K. Astala ◽  
Paul D. Bristowe
Keyword(s):  
Electronic Structure ◽  
Grain Boundary ◽  
Plane Wave ◽  
First Principles ◽  
Driving Force ◽  
Chemical Potential ◽  
Twist Boundary ◽  
Atomic Displacements ◽  
Formation Energies ◽  
Oxygen Chemical Potential

ABSTRACTThe segregation of Nasr impurities to a Σ = 5 [001] twist boundary in SrTiO3 is studied using DFT-based plane-wave pseudopotential techniques. The formation energies of the impurities are calculated as a function of oxygen chemical potential and electron chemical potential. The results indicate a strong driving force for segregation to the boundary and that the Na impurities exhibit acceptor-like behaviour. The atomic displacements caused by the impurities are small both in the bulk and at the grain boundary. Based on the results a model is suggested in which Nasr segregation is driven by soft relaxation of the electronic structure.

On the Segregation of in Solutes to High-Angle (001) Twist Grain Boundaries in Al

1983 ◽  
Vol 25 ◽  
Author(s):  
D. Wolf ◽  
N. Q. Lam
Keyword(s):  
Grain Boundary ◽  
First Principles ◽  
Energy Minimization ◽  
Interatomic Potentials ◽  
Lattice Plane ◽  
High Angle ◽  
Site Selectivity ◽  
Minimization Technique ◽  
Twist Boundaries ◽  
Small Solute

ABSTRACTThe energies of the Σ = 5, 13, and 17 (001) coincidentsite lattice (CSL) twist boundaries in Al containing small amounts of Zn solutes have been calculated using an iterative energy minimization technique in conjunction with interatomic potentials derived entirely from first principles. By determining both the energies of substitution in the bulk and in different sites in the boundary, the site selectivity for Zn segregation at the grain boundary has been investigated. In the lattice plane immediately near the grain boundary, Zn solutes were found to prefer the lower-symmetry non-coincidence sites while, in the next plane, substitution in the coincidence sites is preferred. The effect of Zn-Zn interactions has also been considered for small solute concentrations. It is found that the magnitude of the Zn-Zn interaction energy is remarkably insensitive to the particular sites occupied by the Zn atoms as well as the detailed geometry of the interface.

Axisymmetric Finite-Element Analysis for Interface Migration-Controlled Shape Instabilities of Plate-Like Double-Crystal Grains

2012 ◽  
Vol 460 ◽  
pp. 230-235
Author(s):  
Pei Zhen Huang ◽  
Zhou Zhou Zhang ◽  
Jian Wei Guo ◽  
Jun Sun
Keyword(s):  
Finite Element ◽  
Grain Boundary ◽  
Chemical Potential ◽  
Boundary Energy ◽  
Element Analysis ◽  
Interface Motion ◽  
Double Crystal ◽  
Energy Principle ◽  
Chemical Potential Difference ◽  
Interface Migration

An axisymmetric finite-element method is developed to predict the evolution behavior of microstructures by interface migration. The formulation of the method is conducted on the basis of the energy principle during the interface motion. The computations extend earlier models by accounting in detail for the effects of grain-boundary energy, surface energy and chemical potential difference. The eventual shape of the plate-like double-crystal grain depends on both the initial β and the thermal grooving angle Ψ. For a given β, a critical Ψcexists. When Ψ>Ψc, the eventual shape is one made of two sphere segments with a thermal groove. When Ψ≤Ψc, grain splitting along the grain boundary occurs, and the splitting segments evolve into two spheres, respectively. Both the spheroidization time and the splitting time increase with Ψ and β increasing. The volume shrinkage rate decreases with increasing Ψ.

Fast hydrogen diffusion along the Σ7 grain boundary of α-Al2O3: A first-principles study

2016 ◽  
Vol 41 (47) ◽  
pp. 22214-22220 ◽  
Author(s):  
Fei Wang ◽  
Wensheng Lai ◽  
Rusong Li ◽  
Bin He ◽  
Sufen Li
Keyword(s):  
Grain Boundary ◽  
First Principles ◽  
Hydrogen Diffusion ◽  
First Principles Study ◽  
Α Al2o3

Investigating the effects of a Ga layer on an Al grain boundary by a first-principles computational tensile test

2008 ◽  
Vol 17 (1) ◽  
pp. 015003 ◽  
Author(s):  
Ying Zhang ◽  
Guang-Hong Lu ◽  
Masanori Kohyama ◽  
Tianmin Wang
Keyword(s):  
Grain Boundary ◽  
Tensile Test ◽  
First Principles

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.

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