In this paper, dipolar relaxation processes in epoxy-based polymer were investigated under various polarization conditions, using thermally stimulated depolarization current (TSDC) technique. The TSDC spectrum of un-poled epoxy polymer reveals an unusual negative current, associated with a thermally generated charge carriers, which were due to impurities ionization and structural changes mainly at high temperature (above Tg). β and α dipolar relaxations were detected respectively around 115 °C and 154 °C in conventionally poled sample at TP=110 °C and EP= 3 kV/mm. Dipolar relaxation parameters were evaluated using two techniques: (1) theoretical decomposition of global complex TSDC spectrum, using Bucci-Fieschi expression based on single Debye process, (2) experimental procedure based on selective polarization, commonly known as windowing polarization (WP). The obtained values are TP dependent: relaxation time decreases and activation energy increases when polarization temperature increases. An ω relaxation peak due to water molecule departure was detected around 135 °C, using WP techniques for TP=100 °C Unlike dipolar relaxations, its position is independent of polarization temperature. Complementary thermal analysis investigations by differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA), were made to support some given conclusions.

In this study, the effect of a dense compression nitrogen plasma flow on a microstructure and the elemental and phase compositions of a “tantalum layer-silicon substrate” system is investigated. Predeposited tantalum thin films (∼2 μm thick) on Si(1 1 1) and Si(1 0 0) substrates were exposed to a single plasma pulse or to a series of pulses. The power density absorbed by the target, plasma pulse duration and discharge current were 1.2 GW/m2, 100 μs and 80 kA, respectively. The temperature field distribution and its time evolution were approximately simulated. SEM and EDX analyses revealed the presence of tantalumrich domains consisting of nano-sized particles and spherical multilevel structures. X-ray diffraction analysis showed the formation of crystalline hexagonal tantalum-rich silicides and tantalum nitride. A mechanism explaining the structural changes and phase transformation of the Ta/Si system is proposed.

We characterize and employ a light transmission technique to measure the dispersivity of a solute in the flow of a neutrally-buoyant non-Brownian spherical particle suspension in a Hele-Shaw cell (parallelplate axial flow). Particle radii (a) were 20 and 40 μm, the particle bulk volume fraction ϕbulk was 0.2, and the cell aperture was 420 ± 10 μm. In each displacement experiment a suspension with a colouring solute displaces a transparent one at constant flow rates ranging from 0.721 to 0.928 mL/min (corresponding to solute Péclet numbers (Pes) between 350 and 450). A reference measurement, identical to the displacement ones but without particles in the flow (ϕbulk = 0), were performed in the same experimental assembly for comparison purposes. A light calibration related the transmitted intensity I to the solute concentration c for each combination of ϕbulk and a. The time variation of the solute concentration was found to be well-fitted by the solution of the advection-dispersion equation (ADE) in the range of Pes studied, and consequently a dispersion coefficient D and a dispersivity ld of the solute were measured.

Resistive switching characteristics of Pt/ZrO2/YBa2Cu3O7 sandwiches are investigated for nonvolatile memory applications. Reproducible bipolar resistance switching with an on/off current ratio about 60 and long data retention are achieved. The conduction mechanism obeys Schottky emission in the low resistance state, while Poole-Frankel conduction is predominant in the high resistance state. The resistance switching of Pt/ZrO2/YBa2Cu3O7 sandwiches can be ascribed to migration and redistribution of oxygen vacancies around the ZrO2/YBa2Cu3O7 interface, which switches the conduction between the interface-controlled and the bulk-controlled mechanisms.

Nano structured TiN coatings were prepared by means of active screen plasma nitriding (ASPN) method at a constant temperature of 550 °C for 5, 7.5 and 10 h under three gas mixtures of H2:N2% = 3:1, 1:1 and 1:3. In order to investigate the coating properties such as the chemical composition, surface morphology, surface topography and hardness, several analysis techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and nano indentation were employed. The results indicated that the growth of the TiN film under active screen plasma nitriding deposition had a (2 0 0) preferred orientation. Moreover, it was found that N2-50%H2 atmosphere provides the highest deposition rate leading to the maximum roughness and minimum nano hardness values. Similar observation was obtained by increasing the nitriding time. Furthermore, a model was proposed for the relation between the hardness and the surface roughness of the coating in which higher surface roughness leads to lower hardness.

Investigation the multibody contact-sliding occurred at atomic discrete contact spot will play an important role in determine the origin of tribology behavior and evaluates the micro-mechanical property of nanomaterials and thus optimizing the design of surface texture. This paper carries out large scale parallel molecular dynamics simulation on contact-sliding at atomic scale to uncover the special physical essence. The research shows that some kind of force field exists between nanodot pair and the interaction can be expressed by the linear combination of exponential function while the effective interaction distance limited in 1 angstrom for nanodot with several tens of nanometer diameter. The variation tendency about the interaction force between nanodot array is almost the same between nanodot pairs and thus the interaction between two nanodot array can be characterized by parallel mechanical spring. Multibody effect which dominates the interaction between atoms or molecules will gradually diminish with the increasing of length scales.