An Investigation of the Structural Strains and the Breakdown of Poisson'S Effect in Lattice-Mismatched BCC(110)/FCC(111) Metallic Superlattices

1992 ◽  
Vol 280 ◽  
Author(s):  
A. Fartash ◽  
Ivan K. Schuller ◽  
M. Grimsditch
Keyword(s):  
Structural Feature ◽  
Elasticity Theory ◽  
Plane Strain ◽  
Lattice Spacing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Out Of Plane ◽  
Anisotropic Lattice

ABSTRACTThe strain profiles of individual layers of a selected group of stable bcc(110)/fcc(111) metallic superlattices which have been determined by x-ray diffraction methods are compared, and discussed in terms of a number of mechanisms proposed for explaining their anomalous properties. The superlattices in this group are distinguished in terms of a highly anisotropic lattice spacing mismatch of their adjoining bcc and fcc layers (∼20% vs. 3%). The most prominent structural feature of the bcc layers consists of a highly anisotropic in-plane contraction accompanied with a small out-of-plane strain. The fee layers are found to show large out-of-plane expansions which based on their small in-plane expansions cannot be explained within framework of standard elasticity theory.

scholarly journals Grazing-incidence X-ray diffraction of single GaAs nanowires at locations defined by focused ion beams

2013 ◽  
Vol 46 (4) ◽  
pp. 887-892 ◽  
Author(s):  
Genziana Bussone ◽  
Rüdiger Schott ◽  
Andreas Biermanns ◽  
Anton Davydok ◽  
Dirk Reuter ◽  
...  
Keyword(s):  
Gaas Substrate ◽  
Lattice Spacing ◽  
Molecular Beam ◽  
Grazing Incidence ◽  
Lattice Parameter ◽  
Ion Beams ◽  
Focused Ion Beams ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gaas Nanowires

Grazing-incidence X-ray diffraction measurements on single GaAs nanowires (NWs) grown on a (111)-oriented GaAs substrate by molecular beam epitaxy are reported. The positions of the NWs are intentionally determined by a direct implantation of Au with focused ion beams. This controlled arrangement in combination with a nanofocused X-ray beam allows the in-plane lattice parameter of single NWs to be probed, which is not possible for randomly grown NWs. Reciprocal space maps were collected at different heights along the NW to investigate the crystal structure. Simultaneously, substrate areas with different distances from the Au-implantation spots below the NWs were probed. Around the NWs, the data revealed a 0.4% decrease in the lattice spacing in the substrate compared with the expected unstrained value. This suggests the presence of a compressed region due to Au implantation.

Structural Properties Of Co/Re Superlattices

1991 ◽  
Vol 238 ◽  
Author(s):  
Y. Huai ◽  
R. W. Cochrane ◽  
Y. Shi ◽  
H. E. Fischer ◽  
M. Sutton
Keyword(s):  
Structural Disorder ◽  
Multilayer Films ◽  
Film Plane ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bilayer Films ◽  
Out Of Plane ◽  
Reflectivity Data ◽  
Sharp Interfaces ◽  
Good Agreement

ABSTRACTThe structures of equal-thickness Co/Re multilayer films and several Co/Re bilayer films have been investigated by X-ray diffraction at low and high angles. Analysis of low-angle reflectivity data from bilayer films indicates that interfacial intermixing is limited to three monolayers and that the two interfacial configurations are different. The high-angle X-ray diffraction data show that multilayer films have coherent interfaces and a highly textured structure with hep [002] orientations normal to the film plane for periods 21 Å ≤ Λ ≤220 Å. Detailed structures have been determined by fitting the X-ray spectra to calculated ones using a trapezoidal model. The results indicate that samples with 42 Å≤ Λ ≤220 Å have relatively sharp interfaces, in good agreement with the bilayer results. In addition, an out-of-plane expansion of the Co (002) layer is observed in samples with large Λ and results from structural disorder leading to a reduced atomic density. For Λ <21 Å the interfaces arise from the rougher surfaces of the deposited layers.

Residual Stresses in Similar and Dissimilar Friction Stir Welds of AA5083 and AA6061

2019 ◽  
Vol 813 ◽  
pp. 147-152
Author(s):  
Hernán Gabriel Svoboda ◽  
Leonardo Nicolás Tufaro ◽  
Francisco Javier Belzunce Varela
Keyword(s):  
Residual Stresses ◽  
Lattice Spacing ◽  
Transverse Direction ◽  
Welded Joint ◽  
Travel Speed ◽  
Tension Stress ◽  
X Ray Diffraction ◽  
Dissimilar Joints ◽  
X Ray ◽  
Friction Stir

Similar and dissimilar friction stir welds of AA5083 and AA6061 were produced modifying the location of the materials in the joint (advancing or retreating side) and travel speed (73 and 206 mm/min). Longitudinal and transverse residual stresses were evaluated by X-ray diffraction technique on the mid-length of each welded sample, in the transverse direction to the weld on a 42 mm distance. Unstrained lattice spacing (d0) and full width at half maximum (FWHM) were also measured. A peak of tension stress at the edge of stirred zone was detected, describing an “M” like profile, which were more asymmetrical for dissimilar joints. Variations in d0 and FWHM were also observed through the welded joint, which were related to microestructural changes.

Strong Deviation Of The Lattice Parameter In Si1-x-yGexCy Epilayers From Vegard's Rule

1998 ◽  
Vol 533 ◽  
Author(s):  
J. Stangl ◽  
S. Zerlauth ◽  
F. Schäffler ◽  
G. Bauer ◽  
M. Berti ◽  
...  
Keyword(s):  
Lattice Spacing ◽  
Lattice Parameter ◽  
Negative Deviation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strong Deviation ◽  
Theoretical Predictions

AbstractFrom the comparison of precise determinations of the Ge and C contents of a series of Si1-x-yGexCy epilayer samples (x < 0.18, y < 0.02) by Rutherford and resonant backscattering experiments and x-ray diffraction, the variation of the Si1-x-yGexCy lattice spacing as a function of C content is determined. A significant negative deviation from Vegard's rule is observed, in agreement with theoretical predictions by Kelires.

Reconstruction of Stress and Composition Profiles from X-Ray Diffraction Experiments — How to Avoid Ghost Stresses?

2004 ◽  
Vol 443-444 ◽  
pp. 91-94 ◽  
Author(s):  
Thomas L. Christiansen ◽  
Marcel A.J. Somers
Keyword(s):  
Depth Profile ◽  
Lattice Spacing ◽  
Lattice Strain ◽  
Strain Analysis ◽  
Weighted Average ◽  
X Ray Diffraction ◽  
Stress Strain ◽  
X Ray ◽  
Composition Profiles ◽  
Actual Stress

On evaluating lattice strain-depth or stress-depth profiles with X-ray diffraction, the variation of the information depth while combining various tilt angles, in combination with lattice spacing gradients leads to artefacts, so-called ghost or fictitious stresses. X-ray diffraction lattice-strain analysis was simulated for a model stress-depth profile combined with a composition-depth profile. Two principally different methods were investigated for the reconstruction of the actual stress and composition profiles from the simulated data: - considering the stress/strain determined at a specific depth as a weighted average over the actual stress/strain depth profile - considering the lattice spacing determined at a specific depth, for a specific value for as a weighted average over the actual lattice spacing profile for this direction. On the basis of the results it is possible to propose a preferred method for the evaluation of stress/strain and composition profiles, while minimising the risk for ghost stresses.

Interfacial Composition and Structure in Pt/Ni and Pt/Nb Multilayer Films

1990 ◽  
Vol 187 ◽  
Author(s):  
J.A. Bain ◽  
B.M. Clemens ◽  
S. Brennan
Keyword(s):  
Lattice Spacing ◽  
Grazing Incidence ◽  
Multilayer Films ◽  
Interfacial Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Composition And Structure ◽  
Interfacial Composition ◽  
Alloying Effects ◽  
Coherent Interfaces

AbstractThe interfacial structure of Pt/Nb and Pt/Ni sputtered multilayer films was studied using x-ray diffraction in symmetric, asymmetric, and grazing incidence modes. The grazing incidence and asymmetric diffraction were used to distinguish alloying effects on the lattice spacing from strain in the films. This strain was shown to be consistent with semi-coherent interfaces in the Pt/Ni but not in the Pt/Nb in which another strain generating mechanism dominates.

X-ray structural studies of epitaxial yttrium silicide on Si(111)

1994 ◽  
Vol 9 (6) ◽  
pp. 1434-1440 ◽  
Author(s):  
L.J. Martínez-Miranda ◽  
J.J. Santiago-Avilés ◽  
W.R. Graham ◽  
P.A. Heiney ◽  
M.P. Siegal
Keyword(s):  
Unit Cell Volume ◽  
Film Growth ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Correlation Lengths ◽  
X Ray ◽  
Lattice Constants ◽  
Glancing Angle ◽  
Out Of Plane ◽  
The Mean

We performed a series of glancing angle and reflection x-ray diffraction experiments to study both the in-plane and out-of-plane structure of epitaxial YSi2−x films grown on Si(111), with thicknesses ranging from 85 Å to 510 Å. These measurements allowed us to characterize the mean film lattice constants, the position correlation lengths of the film, and the presence and extent of strain as a function of film thickness. We find that the strain along the basal plane increases as a function of increasing thickness to approximately 1% in the 510 Å film; the corresponding out-of-plane strain is such that the film unit cell volume increases as a function of thickness. The corresponding in-plane microscopic strain varies from 0.5% for the 85 Å film to 0.3% for the 510 Å film. We relate our results to the mode of film growth and the presence of pinholes in the films.

PROPERTIES OF MBE-GROWN SUPERLATTICES AND ULTRA-THIN FILMS

1993 ◽  
Vol 07 (01n03) ◽  
pp. 446-451
Author(s):  
CHARLES M. FALCO ◽  
BRAD N. ENGEL
Keyword(s):  
Lattice Spacing ◽  
Molecular Beam ◽  
Magnetic Transition ◽  
Magnetic Behavior ◽  
Atomic Layer ◽  
High Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Layer 2

We have used Molecular Beam Epitaxy (MBE) to grow single-crystal Co/Pd superlattices and Co/TM (TM=Cu, Pd, Ag) bilayers and sandwiches along the three high-symmetry crystal directions; [001], [110], and [111]. In the case of Co/Pd superlattices, we previously reported from x-ray diffraction measurements that for small Co thicknesses the (001) oriented superlattices are coherently strained in-plane to near the bulk Pd lattice spacing. This strain leads to a very large in-plane magnetoelastic volume anisotropy for these superlattices. Here we report quantitative in situ RHEED measurements of Co deposited on Pd (001) that confirm this coherently strained growth. We have also used in situ polar Kerr ellipticity measurements to study the perpendicular magnetic behavior of Pd/Co/TM (111) sandwich structures, where TM is the non-magnetic transition metal overlayer Ag, Cu or Pd. We observed perpendicular loops with coercive fields of H c ≤ 200 Oe for the uncovered Co films for t co ≤ 6 Å, becoming in-plane above this thickness. However, subsequent deposition of just one atomic layer (≈ 2 Å) of any of the TM over the Co resulted in strongly perpendicular, square hysteresis curves with H c ≥ 900 Oe for all films in the Co thickness range studied.

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