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Modulating extracellular matrix (ECM) elasticity with fibrillar collagen offers great potential for regenerative medicine, drug discovery, and disease modeling by replicating in vivo mechanical signals. This enhances the understanding of cellular responses and fosters therapeutic innovation. However, precise ECM elasticity measurements are still lacking. This study couples time-resolved Brillouin spectroscopy and pulsed laser-induced Scholte wave generation. We measure how collagen fibrillation affects sound velocity and refractive index. These insights are advancing tissue engineering and cellular biomechanics. [ABSTRACT FROM AUTHOR]

Several different soft magnetic materials have been investigated by means of Magnetic Force Microscopy (MFM) using a commercial Atomic Force Microscope (Nanoscope III) with slope detection. The observed contrast of basically solenoidal magnetization distributions in nanocrystalline Fe-Permalloy multilayer and single-layer Permalloy thin film elements not only reveals wall locations, and thus the subdivision of the magnetic volume into domains, but also a decomposition into subdomains hitherto undocumented. A strong influence of edge roughness on the magnetic fine structure is also demonstrated. Additional observations of the classical lancets of a Goss texture in bulk Iron confirm the fact that the symmetries of the observed contrast are consistent with those of the perpendicular component of magnetization within a volume close to the sample surface.

We report on thermal investigations performed in a time resolved experimental scheme. The time domain thermoreflectance (TDTR) is applied in an unusual geometry where the pump and probe beams are not superimposed but focused and shifted. In this way, the determination of the in-plane thermal diffusivity is achieved from temperature snapshots at different time delays. In the first part, taking into account the specific generation process and the detection inherent to the time domain thermoreflectance approach, an analytical solution for the temperature field is obtained for bulk samples, and compared to experimental data. A comparison with the frequency domain thermoreflectance microscopy is also outlined. In Part II section, the lateral heat diffusion in a layered structure is investigated. The comparison of the heat diffusion spreading in case of a highly conductive layer deposited on an insulator substrate and the reverse situation are carefully studied. Finally, we show how the time dependence is efficient to probe and identify material thermal properties or thermal interfacial resistance. [ABSTRACT FROM AUTHOR]

We present a new method to measure without any calibration the thermal effusivity, conductivity, and diffusivity of an insulating layer deposited on a substrate, using lateral heat diffusion. The method is applied to Lithium phosphorous oxynitride, a thin film solid-state electrolyte used in micro-batteries. [ABSTRACT FROM AUTHOR]

We report on the ultrafast vibrational response of single Au-Ag alloy and Au porous nanowires obtained by the template method. The oscillations of the sample reflectivity are correlated with eigenmodes (EM) confined in the nanowire. Taking advantage of a free standing geometry, we are able to detect few harmonics. Coupling electron microscopy and pump-probe investigations with a very high spectral resolution performed on the same wire, we demonstrate that both longitudinal and transverse sound velocities could be obtained for variable Au concentrations. An additional quadrupolar mode is also observed and reproduced by finite element simulation. Finally, porous nanowires are investigated. [ABSTRACT FROM AUTHOR]

Femtosecond pump-probe experiments have been carried out on circular single gold nanostructures lithographed on a silicon substrate with diameters ranging from 1.1 down to 0.3 μm and thicknesses of 175 down to 55 nm. Using three-dimensional finite-element simulations coupled to the specific detection rule of interferometric measurements, we illustrate the effect of intrinsic parameters such as the size and the boundary conditions on the vibrational spectrum. The possibility of using these artificial nanostructures for acoustic transduction in the underlying substrate is investigated. Gold nanostructures are good candidates to generate monochromatic transverse bulk waves in the gigahertz frequency range, with frequency tuned by the dot size. [ABSTRACT FROM AUTHOR]

We investigate experimentally the refraction of antisymmetric Lamb waves at frequencies in the second band of a two-dimensional phononic crystal. The heterostructure is made of a square lattice of air inclusions in a silicon plate. Our experimental scheme is based on the selective generation of narrow band elastic waves at a few megahertz. Both positive and negative refractions are observed. The comparison of our data with computed dispersion curves shows very good agreement. [ABSTRACT FROM AUTHOR]

Recent improvements to measure ultrasonic sound velocities of liquids under extreme conditions are described. Principle and feasibility of picosecond acoustics in liquids embedded in a diamond anvils cell are given. To illustrate the capability of these advances in the sound velocity measurement technique, original high pressure and high temperature results on the sound velocity of liquid mercury up to 5 GPa and 575 K are given. This high pressure technique will certainly be useful in several fundamental and applied problems in physics and many other fields such as geophysics, nonlinear acoustics, underwater sound, petrology or physical acoustics. [ABSTRACT FROM AUTHOR]

According to Cr content, ternary Al1-xCrxNy films structure evolves from hexagonal to cubic phase. Despite numerous studies on their mechanical properties in relation with the deposition process, the relationship between this phase transition and elastic properties has never been deeply studied. In this paper, the transition has been evidenced by picoseconds ultrasonic and Brillouin light scattering at a chromium concentration of 40 at. % and is characterized by a strong increase of C33 and C44 effective elastic constants (respectively, +83% and +70%). [ABSTRACT FROM AUTHOR]

In this study, we investigated the structural and elastic properties of Zr-TL (late transition metal TL = Cu, Co, Ni) thin films metallic glasses (TFMG) deposited by dc magnetron co-sputtering from pure TL targets in Ar plasma discharge. The influence of the deposition parameters on the microstructure, chemical composition and elastic properties of the thin films has been explored. Advanced non-destructive techniques such as the picosecond ultrasonics and the Brillouin light scattering were employed to selectively measure the longitudinal V L and the transversal V T sound velocities, leading to the determination of the elastic constants C 11 , C 44 , respectively. From these data sets, the elastic constants of metastable amorphous single elements a -Zr, a -Cu, a -Co and a -Ni have been extrapolated. Some relationships between elastic moduli (Young's modulus E and shear modulus G = C 44 ) and the structural state either crystalline or amorphous are established. Predicted ductility/brittleness character was emphasized based on the Blackman's diagram, Pugh's ratio and the Pettifor criteria. Equivalently, the newly introduced δ parameter termed as ‘the cooperation parameter’ and related uniquely to the Poisson's ratio ν , confirmed the improvement of ductility with TL alloying. [ABSTRACT FROM AUTHOR]

Multicomponent alloying is an effective design route to increase toughening in hard nitride-based coatings. We provide density functional theory calculations and experimental assessment of the elastic properties of a series of ternary transition metal nitride coatings. M1 1 − x M2 x N films (M1, M2 = Ti, Zr, Ta) were elaborated by reactive magnetron co-sputtering. The structural (texture and microstructure) and growth morphology evolution as a function of film thickness and chemical composition were investigated by X-ray diffraction, X-ray reflectivity, electron probe microanalysis and scanning electron microscopy. The effective elastic constants, C 33 and C 44 , were obtained from longitudinal and transverse sound velocity measurements, using picosecond ultrasonics (PU) and Brillouin light scattering (BLS), respectively. We employ Blackman diagram, as well as Pugh and Pettifor criteria, to derive trends in elastic anisotropy, bonding character and brittleness vs. ductility. The influence of microstructure and preferred orientation on the elastic response of polycrystalline films is discussed. For Ta-rich TiTaN and TaZrN systems, the formation of a nanocomposite system consisting of a mixture of cubic and hexagonal phases has a beneficial contribution to toughening. [ABSTRACT FROM AUTHOR]

Abstract: The composition-dependence of the structure and elastic properties of ternary Ti1– x Zr x N alloys is systematically investigated by combining thin film growth and ab initio calculations. Single-phase Ti1– x Zr x N thin films (0⩽ x ⩽1) with a rocksalt structure have been deposited using dc reactive magnetron sputtering at T s =300°C in Ar/N2 plasma discharges. The structure, stress state and phase stability upon thermal annealing were studied by X-ray diffraction (XRD), while the acoustic and elastic properties were measured using Brillouin light spectroscopy, picosecond ultrasonics and nanoindentation. First-principles pseudopotential calculations of the total energy, lattice constants, bulk modulus, and single-crystal elastic constants Cij for several cubic ordered structures of Ti1– x Zr x N alloys were also carried out. The positive values of the computed formation energies indicate that the homogeneous Ti1– x Zr x N alloys can be only stabilized at high temperatures. However, the magnetron-sputtered thin films were found to retain their as-grown single-phase cubic structure during post-deposition annealing at 850°C for 3h. The calculated equilibrium lattice parameters are in good agreement with the stress-free lattice parameters a 0 determined experimentally from XRD using the sin2ψ method: they both exhibit a positive deviation from Vegard-like linear interpolation. The calculated bulk modulus, elastic constants and Poisson’s ratio gradually decrease from TiN to ZrN. These computed values were used to interpret the experimentally derived elastic constants and Young’s modulus as functions of composition. [Copyright &y& Elsevier]

Abstract: Buckling structures that cannot be simply understood in the frame of continuum elastic theory have been observed by atomic force microscopy on gold films, 630 nm thick, deposited by sputtering method on silicon substrates. X-ray diffraction analyses and finite element simulations have been carried out to characterize the stress levels in and around these buckling structures. The high stress concentration evidenced near the edges of the circular blisters may involve plastic damage resulting in the strong bending of the buckled structures experimentally observed but does not seem to induce a decohesion process of the film/substrate interface. [Copyright &y& Elsevier]

The relation between the nanostructure and the mechanical properties of Nb x -CoCrCuFeNi high entropy alloy thin films was explored. With increasing Nb concentration (0 to 24 at.% Nb), a transition from a single phase face-centered cubic solid solution to an amorphous phase is observed. At intermediary Nb fractions (5 to 15 at.% Nb) a nanocomposite structure is formed that consists of nanosized crystallites embedded in an amorphous matrix. The nanocomposite structure leads to an increase in hardness beyond the Hall-Petch breakdown. The shear and Young's moduli decrease with increasing Nb concentration, which is beneficial for the alloy ductility. [ABSTRACT FROM AUTHOR]

Abstract: For thermal applications, one needs to manufacture titanium nitride based films with as high as possible critical superconductivity temperature while minimizing the mechanical constraints. We investigated the structural and mechanical properties of titanium oxynitride thin films TiN x O y with 0.385≤ x ([N]/[Ti])≤1.13 and y ([O]/[Ti])≤0.3 deposited in a temperature range of 320–400K, at 800W, by reactive DC magnetron sputtering deposition from a Ti target in Ar+N2 plasma discharge. The working pressure was fixed at 0.2–0.25Pa and the nitrogen concentration, x, modified by increasing the N2 flow from 4.2 to 15sccm. The Ar flow was set at 60sccm. We thus tried different physical conditions during realization and characterized the films obtained. We also studied the influence of the substrate onto these film properties. The chemical analysis was performed with the Rutherford backscattering and nuclear reaction analysis techniques. The structural properties of the films were characterized by X-ray diffraction and the mass density by X-ray reflectivity. The electrical resistivity and the critical superconducting temperature were measured by the four-point probe method. Acoustic and elastic properties were determined by the picosecond ultrasonic and the Brillouin light scattering techniques as a function of the nitrogen concentration. [Copyright &y& Elsevier]

We present a detailed experimental study on Mo1-xSix thin films, an archetypal alloy system combining metallic and semiconductor materials. The correlations between structure and elastic response are comprehensively investigated. We focus on assessing trends for understanding the evolution of elastic properties upon Si alloying in relation to the structural state (crystalline vs amorphous), bonding character (metallic vs covalent), and local atomic environment. By combining picosecond ultrasonics and Brillouin light scattering techniques, a complete set of effective elastic constants and mechanical moduli (B, G, E) is provided in the whole compositional range, covering bcc solid solutions (x<0.20) and the amorphous phase (0.20

Abstract: First-principles pseudopotential calculations of the lattice constants and of the single-crystal elastic constants for TixTa1−xN (0≤x≤1) alloys with B1-rocksalt structure were first carried out. These calculations were performed using density functional perturbation theory (DFPT) within the virtual crystal approximation (VCA) for the disordered alloys and the supercell method (SC) for the ordered alloys, with the ABINIT program. For disordered structures, partial comparisons of the lattice constants and of the bulk modulus are provided with calculations that used the coherent potential approximation (CPA) with the exact muffin-tin orbitals (EMTO). For the exchange-correlation potential we used the generalized gradient methods (GGA). The calculated equilibrium lattice parameters by VCA are in good agreement with the stress-free lattice parameters a 0 and exhibit a positive deviation from Vegard''s rule corresponding to a positive bowing parameter while the calculated single-crystal stiffness c 12 and c 44, gradually increase when c 11 decreases from TaN to TiN. In a second stage, we have estimated by homogenization methods the averaged stiffnesses , the Young modulus and Poisson ratio of polycrystalline TixTa1−xN (0≤x≤1) alloys considering a random orientation of crystallites. Finally, comparisons are made with the experimental effective out-of-plane shear elastic modulus C 44 and the effective out-of-plane longitudinal elastic constant C 33 measured by Brillouin light scattering and picosecond ultrasonics, respectively, on thin films elaborated by magnetron sputtering. [Copyright &y& Elsevier]

The confinement of elastic waves within a single defect in a phononic crystal slab is investigated both experimentally and theoretically. The structure is formed by a honeycomb lattice of air holes in a silicon plate with one hole missing in its center. The frequencies and polarizations of the localized modes in the first band gap are computed with a finite element method. A noncontact laser ultrasonic technique is used both to excite flexural Lamb waves and to monitor in situ the displacement field within the cavity. We report on the time evolution of confinement, which is distinct according to the symmetry of the eigenmode. [ABSTRACT FROM AUTHOR]

We comparatively study the elastic properties of the two existing polytypes of tantalum, α-Ta (ground state bcc structure) and β-Ta (metastable tetragonal structure), using density functional theory (DFT) calculations and thin film growth experiments. The lattice parameter and the single-crystal elastic constants c ij for the two allotropic structures were computed using pseudo-potentials with generalized gradient approximation. Sound velocity measurements on single-phase, highly-textured (001) β-Ta and (110) α-Ta films deposited by magnetron sputtering were carried out using picosecond laser ultrasonic and Brillouin light scattering techniques, while hardness H and Young's modulus E were measured using nanoindentation. We found that the β-Ta phase is significantly harder (H ~18.0 GPa) than α-Ta (H ~10.3 GPa), while their elastic stiffness properties and Cauchy pressure p are similar, C 33 ~285–310 GPa, E ~ 188 GPa, p ~ 70–80 GPa, and agree well with the computed values. However, the out-of-plane shear modulus G of the β-Ta film is softer by 28% with respect to that of α-Ta film and DFT values (50 vs. 69 GPa). The present findings reveal that, contrarily to common claims, the β-Ta phase is not at all brittle but elastically and plastically deforms in a compliant way. Its toughness and elastic strain to failure ability is further comprehended from low G / B (0.205) and high H / E (≈0.1) ratios and the absence of radial cracks around indents, which suggests that β-Ta is also a suitable phase for use as wear-resistant coating in biomedical applications. • Sound velocities measured from picosecond acoustics and Brillouin spectroscopy. • Computed elastic constants agree with measured ones for α-Ta. • A significant softening (25%) of C 44 is measured for β-Ta. • Despite being harder, the β-Ta film is found to be more ductile. [ABSTRACT FROM AUTHOR]

Time resolved pump and probe acoustics and first-principles calculations were employed to assess elastic properties of the TbMnO 3 perovskite manganite having orthorhombic symmetry. Measuring sound velocities of bulk longitudinal and shear acoustic waves propagating along at least two different directions in the high symmetry planes (100), (010) and (001), provided a powerful mean to selectively determine the six diagonal elastic constants C 11 = 227 GPa, C 22 = 349 GPa, C 33 = 274 GPa, C 44 = 71 GPa, C 55 = 57 GPa, C 66 = 62 GPa. Among the three remaining off-diagonal ones, C 23 = 103 GPa was determined with a bissectrice direction. Density functional theory calculations with colinear spin-polarized provided complementary insights on their optical, elastic and magnetoelastic properties., (© 2021 IOP Publishing Ltd.)

Because of their role of information transmitter between the spinal cord and the muscle fibers, motor neurons are subject to physical stimulation and mechanical property modifications. We report on motoneuron elasticity investigated by time-resolved pump and probe spectroscopy. A dual picosecond geometry simultaneously probing the acoustic impedance mismatch at the cell-titanium transducer interface and acoustic wave propagation inside the motoneuron is presented. Such noncontact and nondestructive microscopy, correlated to standard atomic force microscopy or a fluorescent labels approach, has been carried out on a single cell to address some physical properties such as bulk modulus of elasticity, dynamical longitudinal viscosity, and adhesion., (Copyright © 2021 Biophysical Society. Published by Elsevier Inc. All rights reserved.)

These data are supplied for supporting their interpretations and discussions provided in the research article "Large influence of vacancies on the elastic constants of cubic epitaxial tantalum nitride layers grown by reactive magnetron sputtering" by Abadias et al. (2020) [doi: 10.1016/j.actamat.2019.11.041]. The datasheet describes the experimental methods used to measure the longitudinal (V L ) and transverse (V T ) sound velocities of cubic epitaxial TaN/MgO thin films, and their related cubic elastic constants (c 11 , c 12 and c 44 ), by the picosecond laser ultrasonic (PLU) and the Brillouin light scattering (BLS) techniques, respectively. First-principles numerical simulations provide additional data using specifically designed supercells of TaN structures, generated either by hand or using the alloy theoretical automated toolkit (ATAT) method [A. Zunger et al. (1990)], with different configurations (random, cluster and ordered) of defects (Ta and N vacancies). Phonons calculations support discussion of dynamical mechanical stability of defected TaN cubic structures. The data illustrate the huge role of vacancies in elastic properties and phase stability of TaN films., (© 2020 The Author(s).)

The monochromatic and geometrically anisotropic acoustic field generated by 400 and 120 nm diameter copper nanowires simply dropped on a 10 μm silicon membrane is investigated in transmission using three-dimensional time-resolved femtosecond pump-probe experiments. Two pump-probe time-resolved experiments are carried out at the same time on both sides of the silicon substrate. In reflection, the first radial breathing mode of the nanowire is excited and detected. In transmission, the longitudinal and shear waves are observed. The longitudinal signal is followed by a monochromatic component associated with the relaxation of the nanowire's first radial breathing mode. Finite difference time domain (FDTD) simulations are performed and accurately reproduce the diffracted field. A shape anisotropy resulting from the large aspect ratio of the nanowire is detected in the acoustic field. The orientation of the underlying nanowires is thus acoustically deduced.

This article reports on the first successful combination of micro Laue (µLaue) diffraction with an atomic force microscope for in situ nanomechanical tests of individual nanostructures. In situ three-point bending on self-suspended gold nanowires was performed on the BM32 beamline at the ESRF using a specially designed atomic force microscope. During the bending process of the self-suspended wire, the evolution of µLaue diffraction patterns was monitored, allowing for extraction of the bending angle of the nanowire. This bending compares well with finite element analysis taking into account elastic constant bulk values and geometric nonlinearities. This novel experimental setup opens promising perspectives for studying mechanical properties at the nanoscale.

We report on gigahertz acoustic phonon waveguiding in free-standing single copper nanowires studied by femtosecond transient reflectivity measurements. The results are discussed on the basis of the semianalytical resolution of the Pochhammer and Chree equation. The spreading of the generated Gaussian wave packet of two different modes is derived analytically and compared with the observed oscillations of the sample reflectivity. These experiments provide a unique way to independently obtain geometrical and material characterization. This direct observation of coherent guided acoustic phonons in a single nano-object is also the first step toward nanolateral size acoustic transducer and comprehensive studies of the thermal properties of nanowires.

We report an innovative high pressure method combining the diamond anvil cell device with the technique of picosecond ultrasonics. Such an approach allows us to measure sound velocity and attenuation of solids and liquids under pressure of tens of GPa, overcoming all the drawbacks of traditional techniques. The power of this experimental technique is demonstrated in studies of lattice dynamics and relaxation processes in a metallic single grain of AlPdMn quasicrystal, and in rare gas solids neon and argon.

The characteristics of a few experimental near-field optical microscopes, located in different laboratories, have been compared on the basis of their ability to image a well-defined submicrometer test object.