Effect of germanium addition on the properties of reactively sputtered ZrN films

For the first time, Zr-Ge-N films were deposited on silicon and steel substrates by sputtering a Zr-Ge composite target in reactive Ar-N2 mixture. The films were characterised by electron probe microanalysis, X-ray diffraction, micro-Raman spectroscopy and depth-sensing indentation. The effects of the Ge content and substrate bias voltage on the films' structure, internal stress, hardness and oxidation resistance were investigated. Substrate bias strongly influenced the chemical composition of the films being observed by means of a steep decrease in the Ge content for negative bias voltages higher than -80 V. In these cases, a significant hardness improvement was registered. For -100 V biased films, in the Ge concentrations range tested in this study, only ZrN grains were evidenced by X-ray diffraction. The film compressive stresses increased with the germanium concentration. An unexpected effect of the Ge content on the films' hardness was observed. In spite of the increase in the compressive stresses of the films with increasing Ge content, the hardness monotonously dropped from 38 GPa for pure ZrN down to 21.5 GPa for 4.6 at.% Ge. Addition of Ge into ZrN-based coatings induced an improvement of the oxidation resistance and it favoured the tetragonal form of zirconia in oxidised Zr-Ge-N coatings.http://www.sciencedirect.com/science/article/B6TW0-4GR33KK-3/1/3d8d2af7ad901266f05a160c3b5fd43

Investigation of ageing effects in PANI-CSA by conductivity and structural measurements

Thermal ageing effect on the highly conducting CSA-PANI was investigated by measurements of the thermal dependence of the conductivity and by X-ray studies of the structure. The non-aged sample shows a metallic-like conductivity around room temperature (RT) and activated behavior dominates the low temperatures. With ageing, the metallic character at RT vanishes, whereas 16% of the sample is still crystalline after 20 days of ageing. A preliminary analysis of the data is carried out using a simple combination of a metallic and a hopping term in series

Densités d’états des modes de réseau dans les polymères conjugués. Une étude par diffusion incohérente des neutrons

Dans cet article nous montrons la possibilité d’obtenir des informations sur l’énergie et la polarisation des modes de réseau de polymères conjugués, à partir de l’analyse de leurs densités d’états mesurées par diffusion incohérente des neutrons sur des films de polymères orientés. Des résultats concernant la dynamique des chaînes du cis-(CH)x et du trans- (CH) )x sont présentés