The aim of this research is to deepen the knowledge of the role of friction on the dynamics of granular media; in particular the friction angle is taken into consideration as the physical parameter that drives stability, motion and deposition of a set of grains of any nature and size. The idea behind this work is a question: is the friction angle really that fundamental and obvious physical parameter which rules stability and motion of granular media as it seems from most works which deal with particle dynamics? The experimental study tries to answer this question with a series of laboratory tests, in which different natural and artificial granular materials have been investigated in dry condition by means of a tilting flume. The characteristic friction angles, both in deposition (repose) and stability limit (critical) conditions, were measured and checked against size, shape, density and roughness of the considered granular material. The flume tests have been preferred to "classical" geotechnical apparatuses (e.g. shear box) since the flume experimental conditions appear closer to the natural ones of many situations of slope stability interest (e.g. a scree slope). The results reveal that characteristic friction angles depend on size and shape of grains while mixtures of granules of different size show some sorting mechanism with less clear behaviour.

Thin film and superlattice deposition of perovskite and related mixed oxides for applications is an emerging and highly active field of research that is attracting increasing attention, because of their various technologically important properties in the strategic fields of environmental and sustainable energy applications. This chapter reviews the most common deposition techniques, namely molecular beam epitaxy, pulsed laser deposition and sputtering. Their potentials for the growth of epitaxial layers with desired properties will be compared. Several examples of thin films and heterostructures of complex oxides and their relevant properties will be discussed with respect to the growth process.

Among the widespread range of applications in which ZrO2 thin films are of interest, they are receiving a peculiar consideration as candidate replacement material in innovative microelectronic devices, such as non volatile memories. In this work, we deposited ZrO2 films on Si (100) substrates by atomic layer deposition at 300C from (MeCp)2ZrMe(OMe) as Zr precursor and using, H2O or O3 as oxygen source. After deposition films were subjected to rapid thermal annealing at 800 C for 60 s in N2. Film thickness is calculated from X-ray reflectivity to be in the 5-60 nm range. Grazing incidence X-ray diffraction reveals that the film crystallographic phase is highly influenced by the oxidizing agent used during the deposition process. While the use of H2O gives films consisting of mixed phases, the monoclinic phase is almost absent in films deposited employing O3, which stabilize in the ZrO2 cubic/tetragonal phases. Upon annealing, the films retain their crystallographic structure, despite a marginal increment of the monoclinic phase. Time of flight secondary ion mass spectrometry depth profiles evidence film uniformity and thermal stability. The evolution of electrical properties of ZrO2 films is discussed as a function of oxygen precursor and thermal treatment. The measured dielectric constant values after 800 C annealing are ~ 24 and ~ 30 in the films deposited using H2O or O3 respectively, in agreement with the different crystallographic phases in the ZrO2 films. © 2011 The Electrochemical Society.

In this paper the deposition of thin films obtained from femtosecond laser ablation of an Al70Cu20Fe10 alloy is presented. In the plasma produced by ablation, a characteristic feature is the presence of hot nanoparticles that become evident several microseconds after the laser shot. The cooling mechanisms of these particles have been analysed together with the evolution of their composition. The results, compared with those previously obtained for Al65Cu23Fe12 quasicrystal, reveal a clear relation between the final composition of the particles and the high-temperature equilibrium vapor pressures of the different elements, suggesting a direct emission from the target rather than a gas phase formation. Analysis of the elemental composition through the cross-section of the as-deposited films helps to illustrate the role of nanoparticles in the film growth.

The crystal structure of a conjugated molecule containing thiophene and fluorenone residues has been determined from powder X-ray diffraction (XRD). Thin films (<40 nm thick) of this molecule, grown in high vacuum (10-5 Pa) onto oxidized silicon substrates, are oriented along with different crystallographic directions. A comparison of XRD in both Grazing Incidence and Bragg–Brentano geometries allowed to perform a quantitative analysis of the various orientations. This approach is generally applicable in the case of multi-oriented films. The results fully account for the poor performance of this molecule in p-type field effect transistor devices.