Structure and Dissociation of 15° Tilt Boundaries in Germanium

1983 ◽  
Vol 25 ◽  
Author(s):  
W. Skrotzki ◽  
H. Wendt ◽  
C. B. Carter ◽  
D. L. Kohlstedt

ABSTRACTThe structure and dissociation of grain boundaries in Ge bicrystals, grown by the Czochralski method, have been analyzed by visible light and transmission electron microscopy. The seed crystals were oriented to yield either a symmetric or an asymmetric grain boundary plane with a 15° rotation about a common <110> direction. The asymmetric boundary, with a {111} boundary plane, dissociated along most of its length into a first order twin boundary (Σ 3) and a symmetric 55° grain boundary (Σ 41c). The symmetric 15° boundary is composed of an array of Lomer dislocations. Contrary to theoretical predictions, this boundary is stable.

1985 ◽  
Vol 57 ◽  
Author(s):  
W. Krakow ◽  
D. A. Smith

AbstractThe atomic structure of representative tilt boundaries in gold has been determined by high resolution transmission electron microscopy. Characteristic and varying regions of decreased density and coordination have been identified and related to mechanisms of grain boundary diffusion and migration


Author(s):  
R.J. Horylev ◽  
L.E. Murr

Read has shown that an arbitrary grain boundary has five degrees of freedom associated with it. Three degrees of freedom are necessary to describe the orientation of one grain with respect to the other, while the remaining two degrees of freedom position the boundary plane between the adjacent grains.Figure 1(a) depicts a general twin boundary-grain boundary intersection. The degrees of freedom for the grain boundary are represented by (HKL)1, (HKL)2, Θ, θGB, ø. Two degrees of freedom are contained in the surface orientations of the grains.


2007 ◽  
Vol 558-559 ◽  
pp. 955-958
Author(s):  
Naoya Shibata ◽  
Fumiyasu Oba ◽  
Takahisa Yamamoto ◽  
Yuichi Ikuhara

In this paper, we characterized atomic structure of a Σ = 3, [110]/{112} grain boundary in a yttria-stabilized cubic zirconia bicrystal. High-resolution transmission electron microscopy (HRTEM) clearly revealed that the grain boundary migrated to form {111}/{115} periodical facets, although the bicrystal was initially joined so as to have the symmetric straight boundary plane of {112}. Atomic-scale process for the facet growth could be modeled by the continuous flippings of atoms at the boundary core.


Author(s):  
A.C. Daykin ◽  
C.J. Kiely ◽  
R.C. Pond ◽  
J.L. Batstone

When CoSi2 is grown onto a Si(111) surface it can form in two distinct orientations. A-type CoSi2 has the same orientation as the Si substrate and B-type is rotated by 180° degrees about the [111] surface normal.One method of producing epitaxial CoSi2 is to deposit Co at room temperature and anneal to 650°C.If greater than 10Å of Co is deposited then both A and B-type CoSi2 form via a number of intermediate silicides .The literature suggests that the co-existence of A and B-type CoSi2 is in some way linked to these intermediate silicides analogous to the NiSi2/Si(111) system. The phase which forms prior to complete CoSi2 formation is CoSi. This paper is a crystallographic analysis of the CoSi2/Si(l11) bicrystal using a theoretical method developed by Pond. Transmission electron microscopy (TEM) has been used to verify the theoretical predictions and to characterise the defect structure at the interface.


1994 ◽  
Vol 77 (2) ◽  
pp. 339-348 ◽  
Author(s):  
Thomas Hoche ◽  
Philip R. Kenway ◽  
Hans-Joachim Kleebe ◽  
Manfred Ruhle ◽  
Patricia A. Morris

1995 ◽  
Vol 10 (4) ◽  
pp. 803-809 ◽  
Author(s):  
W. Ito ◽  
A. Oishi ◽  
S. Mahajan ◽  
Y. Yoshida ◽  
T. Morishita

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.


1995 ◽  
Vol 401 ◽  
Author(s):  
L. Ryen ◽  
E. Olssoni ◽  
L. D. Madsen ◽  
C. N. L. Johnson ◽  
X. Wang ◽  
...  

AbstractEpitaxial single layer (001) SrTiO3 films and an epitaxial Yba2Cu3O7-x/SrTiO3 multilayer were dc and rf sputtered on (110)rhombohedral LaAIO3 substrates. The microstructure of the films was characterised using transmission electron microscopy. The single layer SrTiO3 films exhibited different columnar morphologies. The column boundaries were due to the lattice mismatch between film and substrate. The boundaries were associated with interfacial dislocations at the film/substrate interface, where the dislocations relaxed the strain in the a, b plane. The columns consisted of individual subgrains. These subgrains were misoriented with respect to each other, with different in-plane orientations and different tilts of the (001) planes. The subgrain boundaries were antiphase or tilt boundaries.The individual layers of the Yba2Cu3O7-x/SrTiO3 multilayer were relatively uniform. A distortion of the SrTiO3 unit cell of 0.9% in the ‘001’ direction and a Sr/Ti ratio of 0.62±0.04 was observed, both in correspondence with the single layer SrTiO3 films. Areas with different tilt of the (001)-planes were also present, within each individual SrTiO3 layer.


1990 ◽  
Vol 183 ◽  
Author(s):  
J. L. Batstone

AbstractMotion of ordered twin/matrix interfaces in films of silicon on sapphire occurs during high temperature annealing. This process is shown to be thermally activated and is analogous to grain boundary motion. Motion of amorphous/crystalline interfaces occurs during recrystallization of CoSi2 and NiSi2 from the amorphous phase. In-situ transmission electron microscopy has revealed details of the growth kinetics and interfacial roughness.


1998 ◽  
Vol 526 ◽  
Author(s):  
R. Kalyanaraman ◽  
S. Oktyabrsky ◽  
K. Jagannadham ◽  
J. Narayan

AbstractThe atomic structure of grain boundaries in pulsed laser deposited YBCO/MgO thin films have been studied using transmission electron microscopy. The films have perfect texturing with YBCO(001)//MgO(001), giving rise to low-angle [001] tilt boundaries from the grains with the c-axis normal to substrate surface. Low angle grain boundaries have been found to be aligned preferentially along (100) and (110) interface planes. The energy of (110) boundary planes described by an alternating array of [100] and [010] dislocation is found to be comparable to the energy of a (100) boundary. The existence of these split dislocations is shown to further reduce the theoretical current densities of these boundaries indicating that (110) boundaries carry less current as compared to (100) boundaries of the same misorientation angle. Further, Z-contrast transmission electron microscopy of a 42° asymmetric high-angle grain boundary of YBCO shows evidence for the existence of boundary fragments and a reduced atomic density along the boundary plane


1987 ◽  
Vol 102 ◽  
Author(s):  
Richard J. Dalby ◽  
John Petruzzello

ABSTRACTOptical and transmission electron microscopy have been used to study cracks appearing in ZnSe/ZnSxSe1−x (x ∼ 0.38) superlattices grown by Molecular Beam Epitaxy. It Is shown that when a fracture occurs it is confined, in most cases, to the superlattice and propagates along <011> cleavage directions in these <001> oriented epilayers. Cracks were not observed in all superlattices and their onset is discussed in relation to sulfur concentration, overall superlattice height, individual superlattice layer thicknesses, and stress, tensile or compressive, due to lattice mismatch and thermal expansion differences between buffer layer and superlattice. It was found that by adjusting the controllable parameters, cracks in the superlattices could be eliminated. Orientation and density of these features have been related to asynnmetric cracking associated with the zincblende structure of these II-VI materials. Experimental results are shown to be in agreement with theoretical predictions of critical heights for the onset of cracking.


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