This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited.

No abstract

No abstract

An atmospheric pressure glow discharge (APGD) was used for surface modification of polyethylene (PE) and polypropylene (PP). The discharge was generated between two planar metal electrodes, with the top electrode covered by a glass and the bottom electrode covered by the treated polymer sample. The discharge burned in pure nitrogen or in nitrogen-hydrogen or nitrogen-ammonia mixtures. The surface properties of both treated and untreated polymers were characterized by scanning electron microscopy, atomic force microscopy, surface free energy measurements and x-ray photoelectron spectroscopy. The influence of treatment time and power input to the discharge on the surface properties of the polymers was studied. The ageing of the treated samples was investigated as well. The surface of polymers treated in an APGD was homogeneous and it had less roughness in comparison with polymer surfaces treated in a filamentary discharge. The surface free energy of treated PE obtained under optimum conditions was 54 mJ m −2 and the corresponding contact angle of water was 40˚; the surface free energy of treated PP obtained under optimum conditions was 53 mJ m −2 and the contact angle of water 42˚. The maximum decrease in the surface free energy during the ageing was about 10%.

The best p-type skutterudites with ZT > 1.1 so far are didymium (DD) filled, Fe/Co substituted, Sb-based skutterudites. DD0.68Fe3CoSb12 was prepared using an annealing-reacting-melting-quenching technique followed by ball milling and hot pressing. After severe plastic deformation via high-pressure torsion (HPT), no phase changes but particular structural variations were achieved, leading to modified transport properties with higher ZT values. Although after measurement-induced heating some of the HPT induced defects were annealed out, a still attractive ZT-value was preserved. In this paper we focus on explanations for these changes via TEM investigations, Raman spectroscopy and texture measurements. The grain sizes and dislocation densities, evaluated from TEM images, showed that (i) the majority of cracks generated during high-pressure torsion are healed during annealing, leaving only small pores, that (ii) the grains have grown, and that (iii) the dislocation density is decreased. While Raman spectra indicate that after HPT processing and annealing the vibration modes related to the shorter Sb-Sb bonds in the Sb4 rings are more affected than those related to the longer Sb-Sb bonds, almost no visible changes were observed in the pole intensity and/or orientation.