Quantitative Strain Measurements Research Articles

Quantitative strain-field measurement of 1:1 B-site cation ordered domains and antiphase boundaries in Pb(Sc1/2Ta1/2)O3 ceramics by high-resolution transmission electron microscopy

Quantitative strain measurements of the 1:1 B-site cation ordered domains, antiphase boundaries, and dislocations in a highly ordered Pb(Sc1/2Ta1/2)O3 ceramic have been carried out by high-resolution transmission electron microscopy and geometric phase analysis. A phase shift of π between two adjacent ordered domains across an antiphase boundary is determined unambiguously. The maximum in-plane strain and lattice rotation induced by a dislocation are 9.5% and 5.4°, respectively. In a defect-free antiphase boundary, the maximum in-plane strain and lattice rotation are 1.8% and 0.9°, respectively. The strain mainly concentrates inside the antiphase boundary.

Quantitative measurements of microbubble interactions with surrounding vessels and tissues.

Understanding the coupled interactions between acoustically activated microbubbles and surrounding tissues is important for both diagnostic and therapeutic applications. However, little is known about ultrasound‐induced coupled interactions between microbubbles and blood vessels. In this work, high‐speed microscopy was used to investigate the coupled interactions inside vessels of ex vivo rat mesentery. A 1‐MHz focused ultrasound transducer was used to transmit a single pulse to tissue samples having blood vessel diameters of 10–100 μm. Bubble‐tissue interactions were captured with a high‐speed camera and an inverted microscope. For pressure amplitudes ranging from 1 to 7 MPa, several phenomena were observed: (a) microbubble oscillations caused localized dilation and invagination of the vessels, (b) microbubble jetting occurred where most jets were directed away from the adjacent vessel wall, and (c) connective tissue surrounding the vessels moved with the vessels. The talk will focus on quantitative measurements of vessel motion, strain, and jet velocities. [Work supported by NIH Grants 5R01EB000350, 5R01AR053652, 5P01DK043881, and DK070618.]

Critical Analysis of Different Techniques for Measuring Strain in Si1-yCy Layers Grown by CVD on a Si Substrate

In this work, we performed quantitative measurements of strain in structures consisting of a 30 nm-thick Si1-yCy layer grown by chemical vapour deposition (CVD) on a Si (001) substrate. Total C concentrations vary from 0.67 to 2%. Geometric phase analysis (GPA) of high-resolution transmission electron microscopy (HR TEM) cross-section images and convergent-beam electron diffraction (CBED) with a nanometer resolution as well as Raman spectroscopy and high-resolution X-ray diffraction with a micro- and millimeter resolutions, respectively, were used to deduce the strain within these Si1-yCy layers. These results were compared with the predictions of elasticity theory. Particular interest is paid to the formation of the structural defects within Si1-yCy layers as a function of C concentration, growth temperature and incorporated strain.

Raman spectroscopy determination of composition and strain in [formula omitted] heterostructures

A procedure for the quantitative measurement of composition and strain in epitaxial Si 1 - x Ge x / Si heterostructures by means of Raman spectroscopy for any Ge concentration is presented. The calibration of the parameters of this procedure involved the growth of a set of heteroepitaxial layers spanning the range from pure Si to pure Ge. Different strain conditions were established in a highly controlled way by tailoring the substrate lattice parameter. Through the comparative analysis of reciprocal space mapping and Raman spectroscopy we obtained a set of parameters for the phonon energy variation due to biaxial deformation, as well as calibration curves for the dependence of the Raman band frequencies on alloy composition. With these new calibrations, Raman spectroscopy provides an accuracy in the determination of composition and strain comparable to that of X-ray diffraction, but with the added advantage of high-spatial resolution and resonance-induced surface confinement.

Quantitative Strain Measurement in Sub-45 nm CMOS Transistors by Convergent Beam Electron Diffraction (CBED) at Low Temperature and Nano Beam Diffraction (NBD)

Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008

高温高圧下の変形実験の最新技術

In this article, recent technical developments in high-pressure deformation experiments especially in the field of Earth science are reviewed. The diamond anvil cell has an advantage in performing deformation experiments at very high pressures (up to 160 GPa) compared to other large-volume apparatuses. However, diamond anvil cell has severe limitation in quantitative strain measurements, deformation at high temperatures and deformation with large strain. On the other hand, quantitative rheological measurements at relatively high pressures (up to 10-20 GPa) and high temperatures (up to 1000-2000 K) are possible by using recently developed large-volume deformation apparatuses, rotational Drickamer apparatus, deformation-DIA and “big D-DIA”. Synchrotron X-ray is a powerful tool for in-situ strain and stress measurements in high-pressure deformation experiments using these apparatuses.

Determination of strain within Si1-yCy layers grown by CVD on a Si Substrate

AbstractIn this work, we performed quantitative measurements of strain in structures consisting of a 30 nm-thick Si1-yCy layer grown by chemical vapour deposition (CVD) on a Si (001) substrate at 550 or 600°C. The total C concentration varies from 0.67 to 1.97% that was measured by SIMS. Geometric phase analysis (GPA) of high resolution transmission electron microscopy (HR TEM) cross-section images and convergent beam electron diffraction (CBED) were used to deduce the strain within these Si1-yCy layers. Finite-element simulations were carried out to estimate the impact of strain relaxation in thin areas of a specimen. These results were compared with the data obtained by high resolution X-ray diffraction and Raman spectroscopy and with the predictions of elasticity theory. Particular interest is paid to the formation of the structural defects within Si1-yCy layers as a function of a C concentration, growth temperature and incorporated strain. Both cross-sectional and plan-view TEM specimen configurations were used to obtain quantitative information on the defect size distribution, their density and structure.

Quantitative local strain measurements in compressive strained Ge/tensile strained Si bi-layers grown on top of relaxed Si0.5Ge0.5 virtual substrates

This paper reports on quantitative measurements of strain in a 7.5nm compressive strained Ge/5.1nm tensile strained Si bi-layer grown by reduced pressure chemical vapour deposition on top of a relaxed Si0.5Ge0.5 virtual substrate. Geometric phase analysis of high resolution transmission electron microscopy images acquired using the SACTEM-Toulouse, an aberration-corrected transmission electron microscope, is used to quantify the strain within s-Ge and s-Si layers. Finite element simulations are carried out to estimate the impact of strain relaxation in thin areas of a TEM specimen. Experimental results are compared with the predictions of elasticity theory and finite element simulations.

Coupling between elastic strain and interstitial fluid flow: Ramifications for poroelastic imaging

Elastography refers to a host of imaging techniques that enables the quantitative measurement of tissue displacement and strain in vivo. In its most common modality, ultrasound is used to map the displacement, and an inverse problem to find the tissue biomechanical properties results, based on the tissue’s constitutive equation, and the law of conservation of momentum. In most previous applications, the constitutive model for the tissue is assumed to be elastic or viscoelastic. It is well recognized, however, that soft tissues contain both fluid and solid phases. Furthermore, the fluid may flow within and between several different compartments. This paper addresses the question: Can ultrasound be used to image and quantify interstitial fluid flow in soft tissues from spatio‐temporal patterns of elastic strain? To answer this, we use the mathematical model of vascularized soft tissue, which includes the effects of fluid flow and the possibility of exchange between fluid compartments in conjunction with finite‐element modeling to predict the effects of fluid fluid flow on the spatio‐temporal patterns of soft‐tissue elastic strain.

Nanometer-scale strain measurements in semiconductors: An innovative approach using the plasmon peak in electron energy loss spectra

We present an innovative technique for quantitative measurement of strain in semiconductor materials with high spatial resolution. The plasmon loss peak, seen in electron energy-loss spectra, has been considered following the Drude-Lorentz model, and we find that plasmon energy is extremely sensitive to lattice parameter. We have tested this model using a heterostructure of In0.2Ga0.8As and AlAs layers in GaAs. The experimental data are in excellent agreement with the model. We estimate that strains smaller than 0.036% can be detected, corresponding to a change of x=0.005 in InxGa1−xAs, at a spatial resolution better than 2.8 nm.

Determination of Raman Phonon Strain Shift Coefficient of Strained Silicon and Strained SiGe

The use of Raman spectroscopy to characterize strain in strained Si and strained SiGe has been widely accepted. To use Raman spectroscopy for quantitative biaxial strain measurements, the strain shift coefficient for Si–Si vibration from strained Si (bSi–SiStSi) and strained SiGe (bSi–SiStSiGe) must be known. So far, bSi–SiStSiGe is commonly used to calculate strain in strained Si, which may result in inaccurate strain values. In this work, we report the first direct measurement of bSi–SiStSi by correlating high-resolution X-ray diffraction and Raman spectroscopy, which yields a measured value of -784±4 cm-1. We also show that the strain shift coefficient of SiGe, bSi–SiStSiGe, is a strong function of Ge concentration (x), and follows the empirical relation: b=-773.9-897.7x for x<0.35.

Quantitative strain and stress measurements in Ge/Si dual channels grown on a Si 0.5Ge 0.5 virtual substrate

The incorporation of compressive strained Ge/tensile strained Si bi-layers in the active regions of MOSFETs is a promising route for creating ultimate Si-based devices due to the considerable increase of the mobility of spatially confined holes/electrons. The main challenge in device application is to be able to control and manipulate strain within such thin layers. This paper reports on quantitative measurements of strain in a structure consisting of a 8 nm Ge/5 nm Si heterostructure grown by chemical vapour deposition on top of a relaxed Si 0.5Ge 0.5 buffer layer. Geometric phase analysis of high resolution TEM images is used to measure the strain within Ge and Si layers. The in-plane stress within each layer is deduced. Experimental results are compared with the predictions of elasticity theory and discussed in terms of effect of defect formation.

Quantitative Measurement of Local Shear Strain in Nano-scale using 3D-ET

Quantitative Measurement of Local Shear Strain in Nano-scale using 3D-ET

Characterization of a new luminescent photoelastic coating

The luminescent photoelastic coating (LPC) technique measures the full-field shear strain and its principal direction on the surface of complex three-dimensional components. The measured optical strain response is also dependent on the coating thickness. Achieving uniform coating thickness is difficult, and thus requires thickness correction for accurate quantitative strain measurements. The original formulations of LPC employed a dual-layer coating containing luminescent dyes to transmit both strain and thickness information. This paper will document (theory and experiment) a new strategy: a single-layer coating that incorporates both a luminescent dye and an absorption dye. Dependent on the concentration of the absorption and luminescent dyes, the solution is sprayed onto the object of interest to a minimum threshold thickness that corresponds to a predefined penetration depth. Advantages of the single-layer coating are the elimination of thickness dependency, the elimination of compliance and adhesion issues between multiple layers, simpler data acquisition and post-processing methods, and easier and faster coating preparation and application.

A quantitative thermoelastic stress analysis method for pultruded composites

A non-contact Thermoelastic Stress Analysis (TSA) method is proposed to measure the sum of the direct strain components on the coated surface of thick pultruded composites. Traditionally, TSA methods are used to relate the change of surface temperature to the change of the first invariant of the stress. The proposed method takes advantage of the in-plane transversely isotropic surface layer and relates the measured temperature change to the sum of the surface strains because the latter are directly related to the first invariant of stress. Quantitative strain measurements using the TSA method are verified for multi-axial stress states by comparing the measured in-plane strain invariant in plate samples with a circular hole to those obtained from finite element (FE) simulations. Good comparisons are obtained when compared to the FE strain contours.

Unambiguous sawtooth fringe counting for an active homodyne demodulated interferometric strain gauge

Source wavelength modulation by feedback of the interference signal of an unbalanced fiber-optic Michelson interferometer to the driver of the semiconductor laser source gives rise to sawtooth-shaped fringe's under fiber strain. The fringe asymmetry is utilized for elimination of the fringe counting directional ambiguity via differentiation of the closed-loop interference signal. Initial results of quantitative strain measurements agree reasonably well with the readout of a resistive strain gauge as well as with the theoretically predicted sensitivity. >

Experimental Study of Embedded Fiber‐Optic Strain Gauges in Concrete Structures

Embedded fiber‐optic sensors have the potential of providing valuable information about the condition of the host structure when these sensors are used within an integrated health‐monitoring network attached to the structure. Although such sensors have been developed during the past 15 years for initial specialized applications in aerospace, hydrospace, and biomedical systems, recent attention has been given to the transitioning of these methods to the evaluation of civil structures. This paper reviews the state of the art of the application of fiber‐optic sensors in the structural mechanics field and reports some of the results of an experimental study concerned with the use of embedded short‐gauge‐length optical‐fiber sensors for the quantitative measurement of strain in reinforced concrete structures. Assessment of the validity of the measurements was accomplished through direct comparison between the performance of these sensors and collocated foil strain gauges. Pairs of fiber sensor elements and ref...

Magnetic ordering in strain-controlled epitaxial rare-earth films (abstract)

The magnetic properties of epitaxial rare-earth films and multilayers are known to be sensitive to lattice strain arising from the misfit between the substrate and the epitaxial rare earth overlayer. We find that rare-earth films grow epitaxially, with no coherency strain, onto rare-earth fluoride films on GaAs(111) substrates. This decoupling of the rare-earth film from substrate-imposed coherency strain permits controlled amounts of strain to be introduced into the rare earths by suitably designed sandwich structures. We report quantitative x-ray measurements of strain in films of Dy, Ho, and Er sandwiched by rare-earth fluorides and in Er/Dy/Er sandwich structures grown onto rare-earth fluoride buffer films on GaAs(111). SQUID magnetometry of these structures shows that the unstrained Dy, Ho, and Er films exhibit similar Curie temperatures to bulk crystals. On the other hand, in the case of Er/Dy/Er structures the Curie temperature of Dy is increased as a result of a designed, coherency-induced c-axis expansion of the Dy. The results of a study of strain in Y/Dy/Y structures will also be reported.

Ion beam crystallography of InGaAs epitaxial layers on InP substrates

We report the first direct measurements of the strain in a series of In1−xGaxAs/InP structures by ion beam crystallography. A compression strain of 0.0152±0.0008 was obtained for an In0.47Ga0.53As epitaxial layer on an InP substrate compared with an expansion strain of 0.0126±0.0010 for an In0.58Ga0.42As layer structure. The method used allows quantitative strain measurements to be performed without the need for computer simulations.

The structural sensitivity of electron energy-loss near-edge structure (ELNES)

Calculations are reported using the multiple scattering, Green function method for the transmission electron energy-loss near-edge structure (ELNES) of inner shell excitations. These reveal a high degree of sensitivity to the local crystallographic environment. A plot of the reciprocal of the ejected crystal electron wavevector for a particular feature in the ELNES against nearest-neighbor distance is found to be linear over a small range. This suggests a method for the quantitative measurement of local strain using ELNES obtained with a subnanometer electron probe. An experimental K-edge spectrum from beryllium is used to demonstrate the removal of plasmon multiple inelastic scattering artifact from ELNES by the method of logarithmic deconvolution, without adjustable parameters.