scholarly journals Interfacial Structure of Lattice Mismatched bcc(110)/bcc(110) Transition Metal Superlattices

1993 ◽  
Vol 307 ◽  
Author(s):  
Eric E. Fullerton ◽  
S. M. Mini ◽  
A. S. Bommannavar ◽  
C. H. Sowers ◽  
S. N. Ehrlich ◽  
...  

ABSTRACTWe present structural characterizations of a series of sputtered Fe/Nb and V/Nb superlattices by high-angle x-ray diffraction. Diffraction scans were performed with the scattering vector at various angles (χ) with respect to the layers. χ=0° diffraction spectra (normal to the layers) were fitted to a general structural model to determine the (110) lattice strains, interfacial disorder and interdiffusion. χ>0° spectra probe the lattice strain of the individual layers and the in-plane interfacial coherence. Both systems form incoherent interfaces above a critical modulation wavelength (ΛC). At ΛC, the Fe/Nb system undergoes a crystalline-to-amorphous transition while the V/Nb forms in-plane coherent interfaces.

1990 ◽  
Vol 187 ◽  
Author(s):  
J.A. Bain ◽  
B.M. Clemens ◽  
S. Brennan

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.


The residual lattice strain observed by X-ray diffraction methods in plastically extended polycrystalline aggregates has been investigated. It is shown that, if several diffraction lines are examined, the residual lattice strains vary both in magnitude and in sign. It is known that one of the causes of internal stresses in a plastically deformed polycrystalline aggregate is the variation with orientation of the yield tensions of the crystals in the aggregate. Since only grains with certain orientations contribute to a given diffraction line, the lattice strain measured is not the mean strain in all the crystals, which should be zero, but the average of the strains in those crystals with particular orientations, which may be positive or negative. It is considered that this constitutes one of the reasons for the hitherto unexplained observations which have been made on residual lattice strains. Quantitative conclusions from this explanation are in satisfactory agreement with observations.


Author(s):  
Kazuhiro Fujisaki ◽  
Shigeru Tadano ◽  
Naoki Sasaki

Bone tissue is a composite material composed of hydroxyapatite (HAp) and collagen. Because HAp in bone tissue is a crystal structure, the X-ray diffraction method is available to measure the lattice strain of HAp. A relationship between macroscopic bone tissue strain and lattice strain of HAp in a bone specimen was investigated using X-ray strain measurement under tensile loading. The strip specimens were cut from cortical bone in a shaft of bovine femur. As a result, lattice strains of HAp showed lower value than the bone tissue strain. The strain ratio of the HAp crystals to the bone tissue was formulated with an elastic modulus and volume fraction of HAp in the bone tissue.


1994 ◽  
Vol 38 ◽  
pp. 175-180
Author(s):  
J. M. Vandenberg

Abstract The interfacial structure of a lattice-matched InGaAs/InP/(100)InP superlattice with a long period of ∼630Å has been studied by fully dynamical simulations of high-resolution x-ray diffraction curves. This structure exhibits a very symmetrical x-ray pattern enveloping a large number of closely spaced satellite intensities with pronounced maxima and minima. It appears in the dynamical analysis that the position and shape of these maxima and minima is extremely sensitive to the number N of molecular layers and atomic spacing d of the InGaAs and InP layer and in particular the presence of strained interfacial layers. The structural model of strained inrerfaces was also applied to an epitaxial lattice-matched 700Å InP/400Å InGaAsP/(100)InP heterostructure.


2014 ◽  
Vol 787 ◽  
pp. 307-312 ◽  
Author(s):  
Zhen Yang Liu ◽  
Li Shan Cui ◽  
Cun Yu ◽  
Jiang Jiang ◽  
Da Qiang Jiang ◽  
...  

The influences of different annealing temperatures and pre-strains on the coupling effect between TiNi matrix and the Nb nanowire were studied by means of synchrotron X-ray diffraction in form of variation in lattice strain of the nanowire upon temperature changing for four groups of samples. For every annealing temperature, variation in Nb (110) lattice strains initially increasing with increasing pre-strain and then decreased after 12% pre-strain. A maximum variation in Nb (110) lattice strain was observed approaching 2.4% within the sample 450°C-20min annealed and 12% pre-strained. Such variations in lattice strain of the embedded nanowires upon temperature changing provided the composite great potentials as structural-functional integrated two-way actuators.


2009 ◽  
Vol 42 (2) ◽  
pp. 192-197 ◽  
Author(s):  
Thomas Gnäupel-Herold

A method is outlined that allows the determination of one-dimensional stress gradients at length scales greater than 0.2 mm. By using standard four-circle X-ray diffractometer equipment and simple aperture components, length resolutions down to 0.05 mm in one direction can be achieved through constant orientation of a narrow, line-shaped beam spot. Angle calculations are given for the adjustment of goniometer angles, and for the effective azimuth and tilt of the scattering vector for general angle settings in a four-circle goniometer. The latter is necessary for the computation of stresses from lattice strain measurements.


2004 ◽  
Vol 19 (4) ◽  
pp. 347-351
Author(s):  
J. Xu ◽  
X. S. Wu ◽  
B. Qian ◽  
J. F. Feng ◽  
S. S. Jiang ◽  
...  

Ge–Si inverted huts, which formed at the Si∕Ge interface of Si∕Ge superlattice grown at low temperatures, have been measured by X-ray diffraction, grazing incidence X-ray specular and off-specular reflectivities, and transmission electron microscopy (TEM). The surface of the Si∕Ge superlattice is smooth, and there are no Ge–Si huts appearing on the surface. The roughness of the surfaces is less than 3 Å. Large lattice strain induced by lattice mismatch between Si and Ge is found to be relaxed because of the intermixing of Ge and Si at the Si∕Ge interface.


1949 ◽  
Vol 1 (3) ◽  
pp. 211-224
Author(s):  
G. B. Greenough

SummaryMany papers have been written on the measurement of strain by X-ray diffraction methods and on the interpretation of these strains in terms of stresses. Whereas, during the past few years, the experimental methods of determining the strains have. remained largely unchanged, research has shown that the older techniques for calculating stresses from strains are not always valid.In this paper an attempt is made to describe some of the principles of strain measurement by X-ray diffraction methods to those who are unfamiliar with the methods. The types of stress and strain systems which may exist in polycrystalline metals are then considered, particular attention being paid to the effect of the elastic and plastic anisotropy of the individual crystals. Some indication is given as to how the earlier methods of interpreting X-ray strain measurements should be modified, but no rigid routine method is proposed for use in a general case.


1990 ◽  
Vol 208 ◽  
Author(s):  
Ichiro Hirosawa ◽  
Jun'ichiro Nizuki ◽  
Toru Tatsumi ◽  
Koichi Akimoto ◽  
Junji Matsui

ABSTRACTIn order to investigate the initial oxidation process Qf the Si (111) surface, we have studied the molecular beam deposited Si0 2/Si(111)-7×7 interface structure using grazing incidence X-ray diffraction geometry. We suggest a three-fold symmetry structural model composed of stacking fault layer, dimer layer and additional ordered atoms. The three-fold symmetry structure comes from the preference for oxidation in the faulted half of the 7×7 structure.


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