Zr, V and Zr-V films were evaporated on silicon substrates for evaluating their gettering properties for microelectromechanical systems (MEMS) packaging. The film microstructure was characterized by scanning electron microscope, atomic force microscope, transmission electron microscopy, X-ray diffraction and electrical measurements. Films are amorphous or nanocrystallized according to their composition. Film samples were then activated at various temperatures under argon atmosphere at low pressure of oxidizing species. After annealing, oxygen sorption by the samples was measured by ion beam analysis. Finally, getter films were integrated inside MEMS vacuum packages with a maximum temperature of 300°C. An optimal gettering performance was obtained with the Zr85V15 alloy composition which is close to the limit of the amorphous zone in the phase diagram. For the amorphous films, no correlation is found between oxygen diffusivity and getter performance. The role of grain boundaries in the activation performance of Zr-V getter films was emphasized, by showing that increasing the density of grain boundary enhances the getter performance of the film until an optimum, above which a further increase becomes detrimental to the getter sorption properties. Below this optimum, the enhancement of getter performance by the increasing of grain boundary density can be modelled and allows to predict the getter performance of a Zr-V film knowing its microstructure.

Hydrophobic gold nanoparticles (AuNPs) covalently functionalized with organometallic platinum-containing oligomers (Pt-DEBP n , DEBP = 4,4 '-diethynylbiphenyl) with different chain lengths were synthesized and incorporated into a poly(3-hexylthiophene-2,5-diyl) (P3HT) matrix to obtain inorganic/organic AuNPs/P3HT blends with tuned optoelectronic properties. The Pt-DEBP n (n = 3, 4, 6) chain length was modulated by carefully controlling reaction conditions in a catalyst-free polycondensation reaction and monitored using UV-visible spectroscopy. Spherical AuNPs with a (3.3 +/- 1.1) nm diameter from solid-state microscopies and narrow size distributions, evaluated in colloidal suspension by dynamic light scattering (DLS), were obtained by a two-phase wet chemical reduction in the presence of thiolate organometallic ligands. Structural analyses by FTIR and SR-XPS confirmed the functionalization via Au-S bonds. Platinum-containing ligand introduced additional emissive pathways, including long-wavelength emission, attributed to increased rigidity and reduced nonradiative decay in AuNPs. AuNPs/P3HT blends were obtained with different compositions (from 10 to 90 wt % AuNPs content) by a simple room-temperature mixing approach in organic solvents and spin-coated onto an interdigitated ITO substrate. Homogeneous films with a mean thickness of about 3 nm were revealed by atomic force microscopy (AFM). Electrical I/V measurements (range +/- 10 V) carried out on AuNPs/P3HT blends demonstrated a composition-dependent response. The blend containing 10 wt % AuNPs showed a similar to 30-fold increase in the relative electrical response compared to pristine P3HT and a reduced optical band gap (2.13 -> 2.06 eV). Photoluminescence studies revealed red-shifted and broadened P3HT emission with increasing AuNP content, highlighting strong AuNP plasmon-polymer interactions. Further grazing-incidence wide-angle X-ray scattering (GIWAXS) and nanofocused X-ray scattering measurements (nano-GIWAXS) revealed composition-dependent structural and thermal stability. It is noteworthy that low AuNPs wt % promoted a more effective interconnectivity with P3HT chains, responsible for enhanced electronic coupling in blends compared with pristine counterparts. Results showed that this nanoscale arrangement offers tunable properties for optoelectronic applications.

This paper proposes a new technique to reduce torsional vibrations occurring in the transmission lines of electric vehicles, with high-frequency vibrations (1-5 kHz) that challenge the mechanical passive absorbers traditionally used in thermally powered transmissions. It is based on the resonant electromagnetic (EM) shunt concept, that is extended here to a structure that is free in rotation, thanks to the use of a direct-current (DC) machine acting as the EM transducer. The inductive nature of the DC machine, along with a capacitor placed across its terminals, creates a resonant electrical circuit that induces an antiresonance in the mechanical transfer function of the structure, thereby cancelling vibrations at this precise frequency, that can be tuned on a particular harmonic of the input excitation torque. The study of the amplitude of the antiresonance leads to the development of a figure of merit for the transducer, thereby quantifying its performance with respect to a standard (damped) resonant shunt, tuned to reduce a particular resonance of the structure. It is also shown that the continuous rotation of the structure is unaffected by the EM shunt, which does not induces any electromagnetic braking. An experimental study provides a proof of concept by achieving an antiresonance in the torsional vibratory response of a rotating three degree of freedom structure. The experiments also highlight limitations related to the electrical contact resistance at the interface between the brushes and the commutator of the DC machine.

Digital in-line holographic microscopy is a computational imaging method useful for characterizing the refractive properties of a sample, i.e. the phase shift and absorption. This indirect measurement technique captures a diffraction pattern and uses reconstruction algorithms to retrieve the optical properties of the sample. Since only the intensity of the diffracted wave is recorded on the sensor, this inversion is not trivial, and simple backward propagation leads to artifacts known in optics as the “twin-image”. With advances in deep learning, various algorithms have been developed for the reconstruction of in-line holograms, providing computationally efficient alternatives to iterative algorithms. These algorithms rely either on supervised learning, which requires ground truth knowledge, or physics-based self-supervised algorithms that require additional information, like phase diversity, but require multiple holograms for inference. This paper introduces a new self-supervised physics-based deep learning strategy that leverages phase diversity during training and then reconstructs sample's transmission function from a single in-line hologram during inference. We introduce five datasets of simulated and experimental in-line holograms of beads and bacteria. The proposed method produces accurate quantitative reconstructions similar or even more accurate than those obtained by regularized inversion while reducing the computational time by a factor of 1000.

The crystallization of initially amorphous Ge-rich Ge-Sb-Te nanostructures is investigated using fast thermal pulse heating, coupled with in situ scanning transmission electron microscope-energy dispersive spectroscopy (STEM-EDX) and high resolution (HR)-Transmission electron microscopy (TEM) analyses. Chemical analysis reveals a Te-Ge interdiffusion mechanism occurring at the bottom interface between the Ge-rich GST (GGST) layer and the underlayer (UL). The initially Ge-rich cell shows increasing Te-enrichment as the temperature increases. The onset of crystallization was found to start at 350 degrees C with pure cubic Ge grains appearing first, followed by cubic GST at 390 degrees C. Initially localized at the interfaces, the crystallization of both phases spreads heterogeneously throughout the cell. The spatial distribution of grains is compared with the variations in chemical composition at the nanometric scale.

Electric-field-induced phase transitions are the most important characteristics of antiferroelectric materials, furnishing them with rich functional properties. While they are actively studied for their potential applications such as high-strain transducers and electrocaloric devices, the applied electric field needed to reach the polar phase makes structural studies throughout the full transition of utmost importance. Here, the evolution of both structure and strain in antiferroelectric PbZrO3 thin films was investigated by in situ synchrotron x-ray diffraction during electrical actuation up to 700 kV/cm applied DC electric field. The ferroelectric phase, characterized by its polar order and resulting piezoelectric activity, was found to nucleate at an electric field of 200 kV/cm and to disappear below 160 kV/cm, showing a hysteretic behavior. The variation of the different Bragg peak widths of antiferroelectric and ferroelectric phases revealed the variation of strain distributions in the thin film where antiferroelectric and polar regions coexist during the phase transformation. In addition, the effective longitudinal piezoelectric coefficient of the ferroelectric phase itself, which remains inaccessible by classical macroscopic interferometric measurements, was determined for the first time and reached a value of 67 pm/V, which is quite significant for a thin film clamped on a substrate. These findings provide a clearer understanding of the dynamics of the electric-field-induced phase transition in antiferroelectric PbZrO3 thin films.

Understanding stress accommodation at the atomic scale in nanocrystals is essential for operation in extreme environments. We use high-pressure Bragg Coherent Diffraction Imaging (BCDI) in a diamond anvil cell (DAC) to track three-dimensional strain and defects in individual platinum nanoparticles. The particle hosts an interfacial Shockley partial dislocation up to 2.7 GPa, followed at 5.0 GPa by nucleation of a dense dislocation network accompanied by anisotropic Bragg peak broadening, which later relaxes, indicating plasticity. Upon partial unloading, the interfacial partial reappears and transforms into a perfect dislocation that propagates into the crystal via cross-slip; additional glide events occur, while at 6.7 GPa anisotropic broadening re-emerges. Elastic finite-element modeling predicts shear stress concentrations near the particle-substrate interface, whereas nucleation is observed near the particle top surface. These results show that high-pressure BCDI captures dislocation activity and links reciprocal- and real-space signatures of plasticity in nanocrystals.

Microstructural engineering represents a promising avenue toward controlling the macroscopic response of high-performance magnetic materials, yet the physical origins linking microstructure to magnetic properties remain to be fully established. In this contribution, we establish magnetoplastic control over macroscopic magnetic properties by inducing high densities of extended lattice defects within the prototypical L21-ordered intermetallic MnCu2Al, which serves as an ideal model system. We demonstrate a nearly 95% decrease in the initial net saturation magnetization following a high degree of plastic deformation, with effects that are reversible through annealing. Synchrotron X-ray diffraction and scanning electron nanodiffraction permit microscopic correlation of the changes in magnetic behavior with increasing defect content. Microstructural characterization at the single defect level, coupled with detailed first-principles modeling, suggests the presence of a local antiferromagnetic coupling within the extended defects that is at the origin of the dramatic magnetoplastic effect in these magnetic intermetallics. We ascribe these effects to the planar dissociation of dislocations hosting intervening antiphase boundaries, altering the atomic environment and, in turn, the magnetic coupling in the vicinity of dislocations.

Engineering the properties of semiconductors by changing their crystalline phase is a technologically and economically relevant alternative to doping using foreign elements, with strong potential for photonic and electronic applications. Although major advances have been reported recently for crystal-phase engineering of III-V and group IV semiconductor nanowires, interfacing two mismatched crystalline phases in a nanostructure induces several deformation mechanisms, which remain largely unexplored. Here, using state-of-the-art synchrotron X-ray nanobeam diffraction and transmission electron microscopy, subtle twisting and bending is unveiled within an individual GaAs nanowire containing cubic and hexagonal segments. Their role is discussed in accommodating the inter-reticular spacing fluctuations, and their variations are correlated to the nanoscale phase distribution and to the effect of the NW support. This study brings direct evidence of a complex combination of deformation mechanisms in biphasic nanowires, which opens a new path to tune the nanowire properties with appealing perspectives for device engineering in nanophotonics and nanomechanics.

The behaviour and performance of a flexible beam piezoelectric energy harvester (PEH) in direct and parametric excitation, including the effect of geometrical nonlinearities, are addressed in this paper. First, the electromechanical modelling of the harvester is addressed. A Timoshenko geometrically exact model of a laminated piezoelectric beam in large rotation, including parametric excitation, is proposed, extending previous results of the literature. Then, considering cantilever boundary conditions, it is simplified under Euler-Bernoulli, inextensible assumptions and third order Taylor expansion, suitable for modal expansion. Two perturbation methods are tested to compute vibratory response under direct and parametric excitations. They are both found inaccurate for large amplitude oscillations, leading to a preference for numerical solving by continuation of periodic solutions. PEH behaviours and performances are finally carefully estimated regarding the optimal harvested power in a shunted resistor at resonance. Comparisons between direct and parametric forcing are proposed and the effect of geometrical nonlinearities is estimated. An interesting result is that the harvested power under parametric excitation cannot compete with the one under direct excitation.

The mechanical behavior of piezoelectric semiconductor ZnO nanowires was studied in three-point bending configuration using the custom-built atomic force microscope SFINX coupled with in situ Laue microdiffraction. Besides bending, torsion of the nanowires was shown during mechanical loading. A fracture strength of up to 3 GPa was demonstrated, which is about one order of magnitude higher than that for bulk ZnO. In the case of a piezoelectric material like ZnO, this fracture strength represents the maximum elastic strain that could eventually be converted into electrical energy by the piezoelectric effect. The significantly increased fracture strength found for nanowires compared with bulk ZnO thus offers increased energy-harvesting potential from material flexing. While bulk ZnO is a brittle material, plasticity with the storage of dislocations in the basal plane was shown in the three-point bent ZnO nanowires.

This study explores laser‐induced crystallization and amorphization processes in thin films of Ge‐rich GST (GGST), a tailored phase change material (PCM), monitored in situ using synchrotron X‐ray diffraction. GGST's high crystallization temperature makes it a promising material for embedded memory applications. Experiments employed an 800 nm femtosecond laser source, varying fluence and pulse parameters to induce phase transitions. Key findings include fluence‐dependent thresholds for crystallizing Ge and GST, along with precise control over reversible amorphization. Crystallization maps highlight the differences in fluence and pulse requirements for the transformations. Repeated cycling between amorphous and crystalline states, mimicking PCM operations, confirms the feasibility of controlled phase transitions. Surface imaging using scanning electron microscopy revealed fluence‐induced changes, including ripple formation and ablation at higher intensities. The potential of ultrafast laser irradiation to precisely manipulate GGST phase changes is demonstrated, establishing a foundation for future research on time‐resolved experiments on this and other PCMs.

The widespread use of ceramics faces challenges due to their limited ductility, stemming from a lack of dislocation-induced plasticity. This study focuses on ceria-stabilized tetragonal zirconia a ceramic that benefits from its unique tetragonal-to-monoclinic phase transformation under stress, leading to transformation-induced plasticity (TRIP). Employing a micro-scale in-situ approach, the study aims to understand the mechanisms governing TRIP, particularly focusing on crystallographic features of the transformation. In-situ compression tests using synchrotron light source and Laue micro-diffraction were conducted on single crystal micropillars with various orientations. Results show that crystal orientation significantly affects the mechanical behaviour, with transformation being most likely when the resolved shear stress on {100} planes of the double-cell and along the <010> direction is highest. The martensite theory validates the correspondences obtained experimentally. This research provides insights into enhancing the mechanical properties of ceramics by leveraging the TRIP mechanisms.

We investigate the effect of basal-plane stacking faults on the structural, electronic, and polarization properties of wurtzite GaN and ZnO. This theoretical study is performed within density-functional theory (DFT) using periodic hexagonal supercells. Both formation energies and band structures are obtained by means of total-energy calculations. The type-I stacking fault is observed to have the lowest formation energy, followed by type-II and finally the extrinsic stacking fault. In order to overcome the inherent shortcoming of DFT in reproducing band gaps, the generalized-gradient approximation is used in combination with the modified Becke-Johnson functional. It is shown that all stacking faults studied maintain a direct gap whose value is lower than that in the ideal defect-free crystals. The lowering in the band gap allows the creation of quantum-well regions at wurtzite/zincblende interfaces. In addition, we provide a consistent set of polarization parameters derived from the Berry-phase method. We find a trend of decreasing (increasing) spontaneous polarization and piezoelectric coefficient (polarization charge) in going from type-I to type-II to extrinsic stacking faults. We compare our results to experimental and theoretical data available from the literature and explain the observed trends in terms of the properties of the wurtzite and zincblende polytypes of both materials.

This paper considers the computation of reduced-order models for systems of ordinary differential equations that include non-polynomial non-linearities. An targeted example is the case of a geometrically exact model of highly flexible slender structure, that includes, after space discretisation, trigonometric non-linear terms. With a suitable change of variables, this system can be rewritten in an equivalent one with polynomial non-linearities at most quadratic, at the price of introducing additional variables linked to algebraic equations, leading to a differential algebraic set of equations (DAE) to be solved. This DAE is reduced thanks to a normal form parametrisation of its invariant manifolds and selecting a set of master ones. Arbitrary order expansions are detailed for the coefficients of the change of variable and the reduced dynamics, using linear algebra in the space of multivariate polynomials of a given degree. In the case of a single non-linear mode reduction, a criterion to evaluate the quality of the normal form results is also proposed based on an estimation of the convergence radius of the polynomial asymptotic expansion representing truncated series. The method is then applied to compute a single mode reduction of three test cases -- a Duffing oscillator, a simple pendulum and a clamped clamped beam with von~K\'arm\'an model --, in order to investigate the effect of the algebraic part of the DAE on the quality of the model reduction and its validity range. Then, the more involved case of a cantilever beam modelled by geometrically exact finite elements is considered, underlining the ability of the method to produce accurate and converged results in a range of amplitude that can be bounded thanks to a convergence criterion.

This article deals with the experimental validation of a theoretical model describing the dynamics of a special class of centrifugal pendulum vibration absorbers, designed to reduce the torsional vibrations of rotating machines. The original architecture proposed in this work consists in cylindrical-shaped masses rolling onto each other and acting as double pendulum absorbers. The main interest of these double pendulums lies in the two antiresonances they generate on the main system, which allow to reduce the vibrations at two harmonic orders, unlike standard single pendulum absorbers. The measurements are conducted on an architecture with six double pendulums. They focus on the first rotor antiresonance in the linear and nonlinear regimes, and they are compared to theoretical results from the literature. To the authors' knowledge, this is the first experimental observation of one of the rotor's torsional antiresonances and the first experimental validation of a double pendulum absorber model.

Ti, Zr, V, Zr-Ti, Zr-V, Ti-V and Ti-Zr-V alloy thin films were co-evaporated under UHV. Their composition was characterized by Rutherford Backscattering Spectrometry while their microstructure was characterized directly by X-ray diffraction and scanning electronic microscopy, and indirectly by electrical measurements. Depending on their composition, films are polycrystalline or amorphous and have a resistivity ranging from 60 to 160 mu S2 cm. Amorphous films exhibit resistivities higher than 150 mu S2 cm and negative TCRs, in accordance with Mooij rule. No bulk oxidation in ambient air was detected by electrical measurements over a period as long as 2 years. After deposition, films were activated during a thermal annealing at 5 degrees C/min up to 400 degrees C under 10-7mbar vacuum or 10-3 mbar of H2. An in situ sheet resistance monitoring of the films during annealing allowed to detect their hydrogenation and thus to compare their activation temperatures. Films with amorphous microstructure (ZrV, TiZrV) have lower activation temperatures than single element films and nanocrystalline ZrTi and TiV films. TiZrV has the lowest activation temperature, while single metal films have the highest activation temperatures.