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Focuses on a study which obtained the expressions for the effective second-order elastic constants of the seven crystal systems in terms of their natural second and third order elastic constants. Details of the equation for elastic wave propagation in a homogeneously deformed crystal; Derivation of the pressure derivatives of the effective second-order elastic constants of cubic crystals; Results and discussion.

Presents a study which evaluated the equation state of molybdenum (Mo) at high pressures. Experimental procedure; Calculation of the melting temperature for Mo; Analysis of the shock wave data for hot Mo; Discussion on the Mie-Güneisen equation of state; Extrapolation of ultrasonic elasticity measurements.

The molecular rheology of PFPE becomes critically important in designing optimal lubricants that control the friction/wear and air-bearing by tuning elastic or viscous shear/elongation deformations, which affect the performance and reliability of the hard disk drive. In this paper, we examine the rheological responses of nano blended PFPEs including storage (elastic) and loss (viscous) moduli (G' and G"), by monitoring the time-dependent-stress-strain relationship via nonequilibrium molecular dynamics simulations. By introducing binary blend of nonfunctional and functional PFPEs, we control the degree of liquid/solid-like behavior using the rheology as a complementary tool for design criteria by tuning molecular conformation and diffusion with nano blend ratio. [ABSTRACT FROM AUTHOR]

The isotropic properties of Soft Magnetic Composites (SMC) favor the design of new machine topologies and their granular structure can induce a potential decrease of the dynamic loss component. This paper is devoted to the characterization of the broadband magnetic losses of different SMC types under alternating and circular induction. The investigated materials differ by their grain size, heat treatment, compaction rate, and binder type. It is shown that, up to peak polarization Jp=1.25 T, the ratios between the rotational and the alternating loss components (classical, hysteresis, and excess) are quite independent of the material structural details, quite analogous to the known behavior of nonoriented steel laminations. On the contrary, at higher inductions, it is observed that the Jp value at which the rotational hysteresis loss attains its maximum, related to the progressive disappearance of the domain walls under increasing rotational fields, decreases with the material susceptibility. [ABSTRACT FROM AUTHOR]

An examination of the elastic moduli of a number of the polycrystalline intermetallic compounds LaMxNi5-x (M = Al,Sn) reveals a simple relation between the shear modulus, G, and Young's modulus, E. The results, for a wide range of x, show that the ratio G/E is approximately constant. Further, this constant for these hexagonal close packed (hcp) structures is almost the same as that found many years ago for a large number of hcp polycrystalline metallic elements. This result is shown to be useful for estimating other moduli from the knowledge of only the shear modulus. [ABSTRACT FROM AUTHOR]

We report on the effects of postdeposition annealing ambient on the hysteresis observed in the C-V measurement of Al2O3/GeO2 gate-dielectric stacks fabricated on Ge substrates. The results indicate that two types of oxide trap are responsible for the observed hysteresis: a type-I oxide trap that causes persistent C-V hysteresis and a type-II oxide trap that disappears when gate voltage is biased once in the accumulation region. We show that both types of oxide trap reside in the capacitor annealed in O2 ambient, but that only the type-II oxide trap resides in the capacitor annealed in N2 + 10% H2. Time-domain measurements of absorption current suggest that holes injected into the gate-dielectric stack induce the electronic deactivation of the type-II oxide trap. [ABSTRACT FROM AUTHOR]

In this paper we investigate the magnetostrictive [(3/2)λ100 and (3/2)λ111] and elastic (c' and c4) behavior of single crystalline alloys Fe100-xMox for 2

Shockless compression experiments were performed on x-cut quartz single crystals to examine the effect of loading path and rate on the inelastic behavior. The Lagrangian wave velocity and stress were determined from the measured particle velocities and compared to the previously measured elastic values. The data show that x-cut quartz remains essentially elastic up to stresses greater than 10 GPa during ramp loading, but that the elastic yield behavior is dependent on the sample thickness. These results indicate that the elastic response of x-cut quartz is dependent on the loading path, rate, and sample thickness. [ABSTRACT FROM AUTHOR]

The present study proposes a method for determining indenter shape-independent Young's moduli of thin low-k films from a composite film/substrate nanoindentation response. In contrast to the previous models utilizing empirical fitting parameters, the present authors introduce substrate effect factor determined by the elastic film/substrate mismatch, film thickness, and indenter angle. The new method overcomes several deficiencies of the previous models. Such deficiencies include inability to explain/account for the observed difference in the scale of substrate effect sampled by Berkovich and cube corner indenters. The present model provides consistent Young's moduli of 5.8-6.1 GPa for both types of indenters. [ABSTRACT FROM AUTHOR]

A strain k·p model is used to investigate lattice temperature dependence of the piezoresistivity of p-doped silicon nanobeams in the range of 100–600 K, based on the self-consistent solution to the coupled Schrödinger–Poisson equations. According to quasiharmonic approximation, an analytical semicontinuum atomistic lattice model is presented to describe the effect of size and temperature on elastic constants of the silicon nanobeam by using the anharmonic Keating model. The result presented here indicates the piezoresistive coefficient of the silicon nanobeam, which is dependent on quantum confinement effects, has a negative and nonlinear temperature coefficient. A quantitative comparison of the piezoresistive coefficients calculated with and without considering the elastic constant correction shows that it is crucial to incorporate the size-dependent elastic constant correction in order to quantify the piezoresistivity. [ABSTRACT FROM AUTHOR]

Magnetic hysteresis loss and refrigerant capacity of the NaZn13-type La0.5Pr0.5Fe11.5-xCoxSi1.5 (0≤x≤1.0) compounds have been investigated. The substitution of Co in the La0.5Pr0.5Fe11.5Si1.5 causes the order of phase transition at TC to change from first order to second order at x=0.6. Although the magnetic entropy change decreases with increasing Co concentration, the hysteresis loss at TC also reduces remarkably from 94.8 J/kg for x=0 to 1.8 J/kg for x=0.4 because an increase in Co content can weaken the itinerant electron metamagnetic transition. The effective refrigerant capacity remains at a high value ranging from 355 to 433 J/kg for a field change of 0–5 T as x varies from 0 to 1.0. [ABSTRACT FROM AUTHOR]

We have prepared GexAsySe1-x-y glasses with mean coordination numbers (MCNs) from 2.2 to 2.86. Tg was found to generally increase with increasing MCN while the glass density showed a maximum at MCN≈2.45 and a minimum at MCN≈2.65. The elastic moduli of the glasses were estimated from the shear and compressional wave velocities measured by ultrasonic pulse interferometry. For the first time we simultaneously observed two elastic transition thresholds, the first at MCN≈2.45 and the second at MCN≈2.65, which appear closely correlated with changes in the glass microstructure. The elastic moduli of two groups of samples with the same MCN=2.4 and 2.64 but different compositions suggest that the chemical compositions also have an influence on the elastic properties. [ABSTRACT FROM AUTHOR]

Crack propagation in a wrinkled thin film of gold deposited on polydimethylsiloxane (PDMS) was affected by the presence of folding defects—the ripple dislocations. The ripple pattern, ripple dislocations, and the crack were simultaneously formed after the tensile load applied on the PDMS substrate was removed. The crack, however, was unstable and propagated forward. The propagation rate increased when the crack passed by the ripple dislocations, but less significantly when it advanced near a ripple dislocation dipole. Such crack dislocation interaction implies that the ripple dislocation has an internal stress field. The measured data of the rate process were analyzed based on the theory of fracture mechanics, and an empirical relationship between the crack velocity and the crack extension force was presented. [ABSTRACT FROM AUTHOR]

Molecular mechanics calculations for in-plane stiffness, shear modulus, and the bending rigidity of single-walled carbon nanotubes are reported in this work through the calculations of the strain energy for carbon nanotubes and graphite sheets subjected to various types of loading. Elastic rod and plate theories are employed to link the material properties of carbon nanotubes directly to the molecular mechanics calculations. The in-plane stiffness of carbon nanotubes is about 372–376 J/m2. The bending rigidity is found to be around 1.78 eV for relatively large tubes and graphite sheets. [ABSTRACT FROM AUTHOR]

We report for the first time the complete set of elastic coefficients of the mechanoluminescent material SrAl2O4 stuffed tridymite determined by the first-principles plane-wave pseudopotential total energy method. We calculate other mechanical properties (i.e., bulk modulus, Young’s modulus, and Poisson’s ratio) of this material from the elastic coefficients determined, and compare them with the corresponding experimental and calculated results of typical oxides, indicating that SrAl2O4 stuffed tridymite is a relatively soft ceramic oxide. In addition, we investigate the crystal structure of SrAl2O4 stuffed tridymite at elevated hydrostatic pressures up to 10 GPa and confirm anisotropic deformation in the SrAl2O4 lattice. [ABSTRACT FROM AUTHOR]

The elastic, piezoelectric, and dielectric properties of tetragonal 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 (PMN-35%PT) single crystals were determined. The piezoelectric constant d33 is ∼1250 pC/N; the electromechanical coefficients k15, k31, k33, and kt are 0.70, 0.48, 0.91, and 0.61, respectively. The dielectric properties were measured as a function of temperature for (001)-oriented crystals. Compared with the crystals with compositions in the morphotropic phase boundary, PMN-35%PT crystals have much more stable phase structure from room temperature to Curie temperature, which makes them promising materials for high power applications in fabricating transducers, actuators, and generators. [ABSTRACT FROM AUTHOR]

The paper deals with a two-dimensional numerical model for the evaluation of the electromagnetic hysteretic behavior of thin magnetic sheets when applying a unidirectional magnetic field. The time variation of the magnetization vector m in each space point obeys the Landau-Lifshitz equation. The effective field is the result of several contributions: the applied field, the magnetostatic field, the anisotropy field, and the exchange field. Microstructural features, such as grain size and crystallographic texture, are introduced in the micromagnetic model by dividing the geometry in subregions, each with its own magnetic preferable directions. In the article, numerical experiments are presented aiming at low-frequency applications. The presented micromagnetic model is used to study magnetic memory material properties. [ABSTRACT FROM AUTHOR]

A method for determining hysteresis losses in thin strips of soft magnetic materials is described. It is based on the measurement of a drag force which arises with the movement of the sample through the strong field existing in the space near a permanent magnet. Not associated with macro eddy currents, the force is shown to originate from the magnetic hysteresis of the material, having, in fact, an amplitude equal to the product of hysteresis loss and the area of the sample cross section. Correlation within 18% with the measurements made by conventional methods is shown for a wide range of experimental materials. [ABSTRACT FROM AUTHOR]

Hysteresis phenomenon is one of the important characteristics of soft magnetic materials. A three-dimensional (3D) magnetic property measurement system has been developed. This system can effectively control the locus of the time-varying magnetic flux density vector B and measure the corresponding magnetic field strength vector H in a cubic sample of soft magnetic material. The sample involved in this study is a soft magnetic composite sample made of highly pure iron powder. This paper investigates the B and H loci in 3D space and the power loss when the B loci are controlled to become circles and ellipses lying in three orthogonal planes. It is found that the B and H loci lie in the same magnetization plane, but the H loci and losses depend strongly on the orientation, position, and process of magnetization. On the other hand, the H vectors evolve into a unique locus pattern, and the power losses approach a unique value when the B vectors evolve into the same loci through either a series of small circles or ellipses. [ABSTRACT FROM AUTHOR]

The orientation ratio (OR) is a key issue to achieve high density in longitudinal recording media. Recent recording media have seed layers which exclusively promote small grain growth of the recording layer. In this paper, the effect of seed layers on OR was investigated by the use of various seed materials deposited twice. OR tends to decrease as the thickness of the seed layer is increased; however, the degree of decrease is quite different with seed material. A seed material with small Young’s modulus is preferable for a large OR. These results suggest that OR depends on the interface stress which is relieved as seed layer thickness is increased. Moreover, the relation between the stress in the seed layer and OR was also considered with a multilayer model. [ABSTRACT FROM AUTHOR]

We study the polarization switching of vertical-cavity surface-emitting lasers based on simulations of the spin-flip model. We show that the switching point depends on the ramp signal used to scan the injected current. Fast current ramps enlarge the hysteresis region since the switching point moves to high pump values for increasing injection and to low pump values for decreasing injection. The delay of the bifurcation follows a power law with the slope of the current ramp. [ABSTRACT FROM AUTHOR]

Structural and magnetic characterizations have been performed on exchange-biased multilayers, namely, Ta/X/IrMn/Y/Ta where X and Y are Py and/or Co. In agreement with earlier calculations, magnetic hysteresis loops reveal a clear correlation between the structural quality of the IrMn layer and the variation of the surface exchange energy constant versus its thickness. Moreover, we observe a direct link between the exchange bias variation with temperature and the magnetic disorder. [ABSTRACT FROM AUTHOR]

We used a resonant ultrasound spectroscopy technique to measure the nine independent elastic constants of cyclotrimethylene trinitramine C3H6N6O6 also known by its code designation RDX. The measurements were made on a single crystal grown from acetone containing RDX in solution. The elastic constants in gigapascal units are C11=25.6, C22=21.3, C33=19.0, C23=6.4, C31=5.72, C12=8.67, C44=5.38, C55=4.27, and C66=7.27. [ABSTRACT FROM AUTHOR]

Metal bonded cobalt ferrite composites have been shown to be promising candidate materials for use in magnetoelastic stress sensors, due to their large magnetostriction and high sensitivity of magnetization to stress. However previous results have shown that below 60 °C the cobalt ferrite material exhibits substantial magnetomechanical hysteresis. In the current study, measurements indicate that substituting Mn for some of the Fe in the cobalt ferrite can lower the Curie temperature of the material while maintaining a suitable magnetostriction for stress sensing applications. These results demonstrate the possibility of optimizing the magnetomechanical hysteresis of cobalt ferrite-based composites for stress sensor applications, through control of the Curie temperature. [ABSTRACT FROM AUTHOR]

Magnetostriction measurements from 77 K to room temperature on oriented (100) and (110) disk samples of Fe93.9Be6.1 and Fe88.7Be11.3 reveal substantial increases in λ100 compared to iron. For the 11.3% alloy, λ100=110 ppm, a sixfold increase above that of α-Fe. For the 6.1% alloy, λ100=81 ppm, ∼40% and ∼170% greater than λ100 of comparable Fe–Ga and Fe–Al alloys, respectively, for H=15 kOe. Large differences exist between the values of λ100 and λ111 (λ100>0, λ111<0) and their temperature dependencies. Elastic constants, c11, c12, and c44, from 4 to 300 K were obtained on the same Fe–Be alloys. From these measurements, the magnetoelastic energy coefficients b1 and b2 were calculated. While the magnitudes of the magnetostrictions λ100 and λ111 are widely different, the magnitudes of b1 and b2 are within a factor of 2. The Fe–Be alloys are highly anisotropic magnetostrictively, elastically, and magnetoelastically. For Fe88.7Be11.3 at room temperature λ100/λ111, 2c44/(c11-c12), and b1/b2 are -6.6, 3.55, and -1.86, respectively. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A simple method where the relative change in exchange bias, introduced by external process, is measured by taking only two magnetoresistance readings at a selected field value is presented. Modeling of this measurement process showed that optimal performance can be achieved by engineering the device parameters so that the maximum in the magnetoresistance occurs near the exchange bias field and the width of the magnetoresistance (MR) curve is twice the field value of this maximum MR. Our analysis further showed that the sensitivity can be enhanced by operating the sensor at an operation field close to the exchange bias field. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report estimates of body-centered-cubic titanium’s monocrystal elastic constants C11, C12, and C44. Two constants resulted from measuring a pure-titanium polycrystal at high temperatures using resonant-ultrasound spectroscopy. The third constant resulted from assuming a Zener elastic anisotropy and using inversely Kröner’s monocrystal–polycrystal elastic-constant relationship. Our values are C11=97.7, C12=82.7, and C44=37.5 GPa at 1000 °C. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A general solution for elastic deformation of monolithic and multilayered materials due to external loads and moments, mismatch in thermal expansion, and temperature gradients is derived. Special consideration is given to materials with stress dependent stiffness or gradient in elastic modulus. The relationships can be used to determine the stiffness, thickness, thermal expansion coefficient, or thermal gradient. The fracture of a monolithic material with stress dependent stiffness and the temperature dependence of the elastic modulus and thickness are considered as well as the possibility to use the change in curvature in the case of delamination to determine the fracture energy. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this article, the magnetic properties of nonoriented electrical steel under sinusoidal and distorted excitations are investigated for the whole range of unidirectional mechanical stresses. The distorted flux obtained from the tooth tip of 3 kW induction machine at no-load test was put into the measurement system. The total losses increase for compressive stress both under sinusoidal and distorted excitations. For tensile elastic stresses, the total losses first decrease and then increase in a very similar way for both excitations. In contrast, the difference between total losses under sinusoidal and distorted magnetic fluxes becomes smaller with increase of the plastic strain. This work is a serious step toward complete characterization of the magnetic properties of electrical steel in the teeth area of induction machines. A deeper insight of that problem can improve the design of induction machines and other electromagnetic devices. [ABSTRACT FROM AUTHOR]

Uniaxial stress-strain measurements were performed on polycrystalline Tb[sub 76]Dy[sub 24] alloys which exhibit “giant magnetostriction” at cryogenic temperatures. The Young’s moduli were reduced by up to a factor of five at 77 K, in comparison to their values at 300 K. We attribute this reduction to a mechanical compliance from domain rotation. Large mechanical hysteresis is also found in nominally elastic stress-strain curves measured below the Curie temperature. Hysteretic curves from 0 to 25 MPa demonstrate up to 19% dissipation of the applied mechanical energy. The anisotropy of thermal expansion was also measured and used as a parameter for the degree of crystallographic texture. This anisotropy was correlated to bulk magnetostriction and to mechanical hysteresis. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study which examined the Christensen theory of elastic behavior of composite materials. Generalization of Christensen's theory; Characteristics of a composite material; Information on the computation of compression modulus and shear modulus of a composite consisting of several types of spherical inclusions in a continuous matrix phase.

Considers the transverse Young modulus of specially constructed plane composites for various volume fractions of filler. Values of the phases' elasticity constants chosen for calculation of the upper and lower bounds of the transverse-Young modulus variation; Preparation of the sample plates; Method used to calculate the effective modulus in the study.

Presents a study which measured the dispersion of localized elastic modes in thin supported gold layers by Brillouin scattering. Details of experimental techniques used; Information on the possible technical applications of elastically different media; Features of the tandem Fabry-Perot interferometer beings used in Brillouin scattering.

Presents a study which measured elastic, piezoelectric, and dielectric properties of the barium lanthanum gallium[sub3] oxygen[sub7] crystal. Method of the study; Results and discussion; Conclusion.

Presents a study which calculated the pressure derivatives of bulk, shear and Young's moduli, and of the Poisson's ration of a number of polycrystalline aggregate of hexagonal metal. Previous studies on the calculation of the elastic properties of a polycrystal from the elastic moduli and their pressure derivatives; Formulae for hexagonal materials in the Voight and Reuss schemes; Use of monocrystal elastic constant pressure derivatives in the calculations.

Presents a study which measured the elastic stiffness and thermal expansion coefficient of boron nitride (BN) films. Process which produces BN; Technique used in the measurement of the stress of the films; Description of the physical properties of substrate materials.

Reports on a study which combined the electromechanical and thermal breakdown theories, used in the numerical analysis of electrical breakdown in polyethylene terephthalate films. Combination of the theories into heat balance equations which depended on Young's modulus; In-depth look at polyethylene terephthalate films; Methodology used to conduct the study; Results of the study.

Deals with a study which investigated the possibility of spectral gaps in model elastic periodic composites with continuous variation of elastic properties. Presence of spectral gaps in the composites; Information on the model continuous composite; Numerical methods and results.

Presents a study which measured the three independent elastic stiffness constants of single-crystal cubic boron nitride using Brillouin scattering. Characteristics of boron nitride; Origin of the extraneous Brillouin peaks in the spectra; Basis of the error in fitting theoretical equations of state to experimental volume versus pressure data.

Presents a study which described a method for determining both magnetorestriction and elastic modulus by ferromagnetic resonance (FMR). Theoretical background; Experimental procedure; Results of the study.

Provides information on a study that used the mechanical resonance frequency method in measuring Young's moduli for thin films and substrate. Experimental procedure; Results and discussion on the study; Conclusion.

Provides information on a study that examined the elastic behavior of mixed lithium-cadmium ferrites of different compositions. Experimental procedure; Results and discussion on the study.

A two-dimensional analysis of the in-plane misfit stress and its elastic relaxation in rectangular patterned heteroepitaxial SiGe/Si multilayer structures on Si substrate is presented. Based on the model of relaxing film stress the distribution of the misfit stress versus distance from the free surface of a multilayered mesa edge is calculated. By superposition of the isolated stress fields of the mesa edges, the biaxial misfit stress distribution in a finite heteroepitaxial thin-film structure on thick substrate is obtained. The formalism developed permits the determination of the variation of misfit stress values as a function of material and size characteristics of the patterned multilayer-substrate system. An elementary application of the theoretical analysis of the biaxial state of stress existing in the structured layer system is discussed briefly. [ABSTRACT FROM AUTHOR]

The compressional VP wave velocity, refractive index n, and acoustic attenuation coefficient Γ of breakaway glass and liquid have been measured by high-resolution Brillouin spectroscopy up to 170 °C in platelet and backscattering geometries. A marked break in the compressional wave velocity-temperature relationship is observed at the glass transition temperature of 52 °C consistent with the glass transition temperature observed in ultrasonic experiments on the same sample. The temperature dependence of the compressional wave velocity determined by Brillouin scattering and ultrasonic interferometry are compared. [ABSTRACT FROM AUTHOR]

Presents information on a study which examined the elastic strain limit of polycrystalline mixed AgCl[subx]Br[sub1-x] optical fibers. Properties of the fibers; Experimental method used; Results and discussion; Conclusions.

Investigates the longitudinal elastic properties of tellurite glasses. Qualitative interpretation of the increase in the modulus; Information about the structure of the glass deduced after calculating the number of network bonds per unit volume and the crosslink density; Role of halogen inside the glass network.

Presents information on a study which analyzed the elastic-plastic deformation of the surface and inner layers of the metallic glass (MG) Co[sub77]Fe[sub74]Cr[sub7]Si[sub8]B[sub4] ribbon using the indentation method. Analysis of the elastic-plastic properties of the MG surface; Discussion of the resulting MG isothermal annealing; Assessment of the effect of superplasticity of as-quenched MG surface.

Presents information on a study which estimated the elastic constant of zinc-blende aluminum nitride, gallium nitride and indium nitride. Correlation between the elastic properties of the wurtzite and zinc-blende crystal structures; Calculation of elastic constants; Measurement of critical layer thickness for the nitrides.

Presents a study which examined the interaction between the elastic and magnetic properties of the ternary alloy terbium[sub0.3]dysprosium[sub0.7]iron[sub2]. Experimental details; Results and discussion; Conclusion.

Presents a study which reported the results of audio frequency elastic measurements in the alloy series Fe[sub80-x]Ni[subx]Cr[sub20] through its various magnetic transitions. Method used in identifying and preparing the alloy; Evidence supporting prediction based on mean-field theories for sound propagation in spin glass.