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The effect of pressure on mechanically alloyed trigonal nanostructured SnSe2 (n-SnSe2) was studied by in situ angle-dispersive X-ray diffraction up to 25.8 GPa. The pressure dependence of lattice parameters and unit cell volume was investigated. By fitting the lattice parameters and unit cell volume to a third-order Birch–Murnaghan equation of state for several values of the applied pressure, the bulk modulus B0, its first derivative B′, and the linear moduli along the a- and c-axes were determined. The effect of pressure on the z coordinate of site 2d occupied by Se atoms was investigated using pair distribution function analysis. The results were compared with experimental and theoretical studies of SnS2 and SnSe2 reported in the literature.

A thermodynamic analysis of the Cr-Ge system suggested that it was possible to produce a nanostructured Cr3Ge phase by mechanical alloying. The same analysis showed that, due to low activation energies, Cr-poor crystalline and/or amorphous alloy could also be formed. In fact, when the experiment was performed, Cr11Ge19 and amorphous phases were present for small milling times. For milling times larger than 15 h these additional phases decomposed and only the nanostructured Cr3Ge phase remained up to the highest milling time used (32 h). From the differential scanning calorimetry measurements, the Avrami exponent n was obtained, indicating that the nucleation and growth of the nanostructured Cr3Ge phase may be restricted to one or two dimensions, where the Cr and Ge atoms diffuse along the surface and grain boundaries. In addition, contributions from three-dimensional diffusion with a constant nucleation rate may be present. The thermal diffusivity of the nanostructured Cr3Ge phase was determined by photoacoustic absorption spectroscopy measurements.

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Araucaria (Araucaria angustifolia) is a tree species found in the Southeast and South of Brazil. It is also known as Brazilian pine, presenting fruits of high acceptance. However, its processing generates by-products that are little used. Thus, this work aimed to extract and characterize the cellulose obtained from the pinion husk, as well as to evaluate the contents of ash, lignin, cellulose and α-cellulose in its composition. The raw material and the extracted cellulose were characterized by X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). As for the contents of chemical composition detected, the husks showed 1.6% ash, 7% extractives, 34% lignin and 55% cellulose, being 46% α-cellulose and 9% hemicellulose. It was observed by XRD that the removal of amorphous materials resulted in a gain of crystallinity (from 19 to 33%). Proving the efficiency of the extraction, the characterization of the cellulose obtained was shown to be of high purity, since the main band of the lignin (FTIR) and the amorphous materials of the cellulosic sample (TGA) disappeared. Finally, this work shows that the pinion bark is a rich source of cellulose, making it possible to obtain nanocrystals.