Silver (Ag) films were prepared by DC magnetron sputtering deposition at different substrate temperatures (25–450 °C) and film thicknesses (100–800 nm) and their morphological, optical, electrical and structural properties were investigated. Atomic force microscopy (AFM) was employed to study the surface topography of the thin films. The grain size as well as surface roughness of the films is strongly dependent on the temperature and the film thickness. X-ray diffraction experiments showed the intensity enhancement by increasing substrate temperature, also by increasing film thickness. The optical properties were determined by means of spectrophotometric analysis. It is found that the optical reflection is not affected significantly with substrate temperature and film thickness. The electrical resistivities of films were determined by four-point probe measurements. The experimental results indicate that the films with higher thickness and deposition temperature have the lowest resistivity.

By means of the new techniques of magnetically driven quasi-isentropic compression based on compact capacitor bank facility CQ-1.5 developed by us, the dynamic compression of two mixed HMX-based plastic bonded explosives (PBX) explosives is researched under ramp wave loading. A pressure of 5–8 GPa over 600–800 ns is realized on explosive samples by optimizing loading electrodes and controlling charging voltages of CQ-1.5. And loading strain rates vary from 105 1/s to 106 1/s along the thickness of explosive samples. For experiments, the particle velocities of interface between explosive samples with different thicknesses and LiF windows are measured to determine material response by a displacement interferometry technique of Doppler pins system (DPS), and the experimental compression isentropes of researched explosives are obtained using the data processing method of backward integration and Lagrangian analysis for quasi-isentropic compression experiments, which are in agreement with the theoretical isentropes based on Mie-Grüneisen equation of state (EOS) and the results by Baer. For simulations, one-dimensional hydrodynamics code SSS is used to analyze the dynamic process, and the calculated results of particle velocity of interfaces are consistent with the experimental ones. Finally, one of the explosive constituents, the binder fluoride rubber F2311, is also investigated using this technique, and some properties under ramp wave loading are gained.

We have designed and built a hemispherical retarding field energy analyzer in order to facilitate characterization of large area electron emitters (typically field emitter arrays with active areas up to 1 cm2) with large angular aperture. A complete numerical model of the analyzer has been built, including perturbations due to secondary particles, in order to determine the analyzer performances. The analyzer energy resolution is better than 100 meV for an energy range up to 120 eV. The analyzer has a global field of view of 112° and allows measurements of the energy distribution of the beam as a function of the emission angle, as well as measurements of the beam intensity profile along any section of the beam. We have successfully used the analyzer to characterize the electron beam emitted by 1 cm2 Mo microtips-based field emitter arrays.

The purpose of this paper is to approach stimulated infrared thermography possibilities in terms of measuring longitudinal thermal diffusivity of mural paintings in situ. The measuring method principle is first submitted. It is based on temporal analysis of changes in the characteristic radius beams of spatial profiles of the photothermal signal, measured on the spot of the laser excitation. The feasibility of the method is demonstrated, thanks to a series of simulations. Lastly, the method enables to correctly estimate longitudinal thermal diffusivity in a test sample, and further in a fragment copy of “Saint Christophe” belonging to the Campana collection in the Louvre.

Morphological and topological quantification of complex pore networks is of great relevance for environmental engineering, earth science and industry. Recent developments of 3D imaging techniques such as X-ray microtomography or X-ray microscopy provide an opportunity to perform a comprehensive analysis of the pore network topology. Such an analysis is crucial to understand how transport or mechanical properties evolve during the growth and/or the aging of a pore network, especially near a percolation threshold. In the first part of this work, we present some properties related to the graph of retraction of a 3D pore network, a powerful way to characterize the topological evolution. In the second part, we analyze the topology of an evolving 3D pore network in the vicinity of a percolation transition. Two distinct scenarii of evolution are presented. The last part is dedicated to an experimental example of evolving pore network: the setting of an ordinary cement paste probed in its early age by synchrotron X-ray microcomputerized tomography.

Fracturing of rocks and other geomaterials involves multi-scale processes, from the nucleation of small cracks, their propagation into a complex heterogeneous solid, to their final arrest. In the past 10 years, advances in X-ray tomography imaging techniques, either three dimensional or four dimensional when time-lapse acquisitions are performed, allow detecting fractures at small scale and the growth and coalescence of tiny cracks into well-developed fractures. Some of these fracturing processes involve the coupling between fluids, chemical reactions and fracturing. In the present study I illustrate some of these processes, how they can be imaged using high-resolution X-ray computed tomography; and how conceptual models can make the link between microscopic processes and macroscopic fracturing. This concerns a wide range of applications in geophysics, from fundamental understanding of the rheology of rocks in the Earth’s crust, to salt damage of cultural heritage monuments, hydraulic fracturing of underground reservoirs or emerging technologies of non-conventional hydrocarbon recovery and the underground geological storage of carbon dioxide.

Measurement of displacement time and length scale dependent dynamics by pulsed gradient spin echo nuclear magnetic resonance in porous media directly provides the preasymptotic hydrodynamic dispersion coefficient. This allows for comparison with nonequilibrium statistical mechanics models of hydrodynamics dispersion in porous media. Preasymptotic dispersion data and models provide characterization of porous media structure length scales relevant to transport and are related to the permeability and sample heterogeneity.

We present multiscale experiments assessing the impact of the recrystallization dynamics of sodium sulfate and sodium chloride on damage observed in sandstone during humidity cycling. The deliquescence of both salts leads to the formation of homogeneous salt solutions which, upon drying, can reach high concentrations before (re)crystallization. For sodium chloride that has only a single crystalline phase, precipitation manifests itself as the fast growth of a small number of nuclei which grow to larger sizes in time. For sodium sulfate, with different crystalline phases, we observe that kinetically the precipitation of the thenardite (the anhydrous phase with the higher solubility) appears to be favored. The comparison of these results with those obtained when rewetting of crystals is done with liquid leads to the conclusion that the size of crystals that precipitate upon recrystallization is an important ingredient for explaining the damage observed in stones, besides the crystallization pressure that is usually invoked.

Permeability of reservoir rocks can be strongly altered by salt precipitation induced by drying. Indeed, gas injection in deep saline aquifers leads first to the brine displacement. The liquid saturation decreases near the injection point and reaches a residual water saturation. But at longer time, the water mass transfer to the gas phase by evaporation can become significant and the dissolved salt can precipitate in the porous structure. The solid salts fill the pores and the permeability decreases. Permeability alteration by salting out is a risk of injectivity decline in the context of CO2 geological storage in saline aquifers where high level of gas injection has to be maintained over decades. However, this problem has been poorly investigated. It implies physical processes that are strongly coupled: drying, water and gas flows in the porous structure and precipitation. This work is an experimental investigation aiming at measuring on natural rock samples the permeability alteration induced by convective drying where dry gas is injected through the sample. We show that alteration of permeability is strong and total blockage of the flow is even possible. We also show that the change in porosity due to the solid salt is heterogeneous along the rock samples. A local permeability-porosity relationship has been estimated from the measurements and we could deduce the permeability alteration function of time by modeling the drying dynamic. We show that it starts very early because capillary backflows are extremely efficient in this process to accumulate solid salt near the injection surfaces.