Note on the methodology of measuring the attenuation of acustic waves in solid state

The presented paper is a note on the methodology of measuring the attenuation of ultrasonic waves in the case of observation device not facilitating a direct measurement of the attenuation based on the definition of the ratio of amplitudes. Instead the ratio of the areas of two subsequent acoustic impulses is acquired

Spectroscopic evidence for large (>>1 µm) lithium-colloid creation in electron-irradiated Li2O single crystals

We have created lithium metal colloids by electron-irradiating single crystals of lithium oxide near 0°C. The striking feature is the observation of two kinds of colloids manifesting themselves as two EPR metallic lines, the narrow line corresponding to small metallic clusters (size < 1 µm) and the broad one associated with large metallic colloids visible by optical microscopy (~ 20 µm). The latter are also observed by NMR. A further indication for the presence of colloids of different types is the differing recovery behavior of the two EPR lines in an annealing treatment

Soil contamination by heavy metals at Libiola abandoned copper mine, Italy

Exploitation of ores has surely represented a risk for contamination of environmental matrices for a long time. This paper reports the results of a study concerning soil contamination by heavy metals at Libiola abandoned copper mine (Italy). This deposit has surely got special importance in Italy because of its historical, environmental and mining features. From a historical viewpoint, Libiola deposit was known since Copper Age, with maximum exploitation at the end of the 19th century. Our investigation plan was elaborated in order to characterize the environmental matrices there, and it provided for inspection of the zones (included in the valley of Gromolo stream) which, according to our preliminary studies and according to literature, could be most affected by past mining activity. Within our selected zones, some soils (even cultivated) were collected in order to check their contamination by heavy metals. Results from the analysis of the collected soil samples showed that the content of heavy metals often exceeds limits provided by the Italian Law 152/06. The knowledge of situation concerning pollution can give useful indications about the influence of mining activities on the surrounding environment, and it can also be valid support in order to organize an optimal future use of the studied mining area, which has been abandoned since its closure (1962).Web of Science23334533

Lithium colloids and color center creation in electron-irradiated Li2NH observed by electron-spin resonance

4 pagesInternational audienceWe have irradiated Li2NH powder with MeV electrons at room temperature and investigated the introduced defects with electron spin resonance. CESR indicates the presence of nanosize metallic Li colloids seen as a Lorentzian line with a g = 2.0023 and a line width DeltaH = 50 microT. A second, broader, signal (DeltaH = 3 to 4 mT) appears superimposed upon the Li line at low T (Curie-type behavior) which exhibits complex T-dependence with a break near 180 K for its g-value and DeltaH. We are suggesting for the latter a vacancy-type defect in the NH-sublattice, with freezing of its H-component below 180 K. When heated both the Li colloids and the color centers anneal around 100 C probably due to hydrogen evolution and subsequent chemical degradation