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The mechanisms of silicon nanocrystal structure formation in amorphous Si films have been studied for a relative Ni impurity content varying between 0.1 and 10at.%, i.e., from a Ni doping range to the Si–Ni alloy phase. The films, deposited by the cosputtering technique at 200°C, were submitted to isochronal (15min) annealing cycles up to 800°C. Four different substrates were used to deposit the studied films: crystalline (c-) quartz, c-Si, c-Ge, and glass. Both the two orders of magnitude impurity concentration range variation and the very short annealing times were selected on purpose to investigate the first steps of the mechanism leading to the appearance of crystal seeds. The conclusions of this work are the following: (a) Ni impurity induces the low-temperature crystallization of amorphous silicon; (b) the NiSi2 silicide phase mediates, at the surface or in the bulk of the film, the crystallization process; and (c) the onset of crystallization and the crystalline fraction of the samples at each temperature depend not only on the Ni impurity concentration, but also on the nature of the substrate.

Silver and gold films with thicknesses in the range of 120-450 nm were evaporated onto glass substrates. A sequence of slits with widths varying between 70 and 270 nm was milled in the films using a focused gallium ion beam. We have undertaken high-resolution measurements of the optical transmission through the single slits with 488:0 nm (for Ag) and 632:8 nm (for Au) laser sources aligned to the optical axis of a microscope. Based on the present experimental results, it was possible to observe that (1) the slit transmission is notably affected by the film thickness, which presents a damped oscillatory behavior as the thickness is augmented, and (2) the transmission increases linearly with increasing slit width for a fixed film thickness.

The structural, optical and morphological properties of amorphous Ge 100−x Mn x films deposited by conventional radio frequency sputtering were investigated in the 0 < x < 24 at% composition range. After deposition, all films were submitted to isochronal thermal annealing treatments up to 600• C and analysed by x-ray diffraction, Raman scattering, optical transmission spectroscopy and scanning electron and atomic force microscopy techniques. Based on the present experimental results, it is possible to affirm that (a) with no post-deposition treatment, the films are essentially amorphous and the Mn atoms were effectively and controllably incorporated into the amorphous host; (b) Mn species induce the crystallization of the amorphous Ge 100−x Mn x films at temperatures that depend on the Mn concentration; (c) after crystallization, the ferromagnetic Mn-rich phase Mn 5 Ge 3 was found in films with the higher Mn contents; (d) at these higher [Mn], the thermal treatment induces the development of nanoparticles (typically ∼50 nm high and ∼250 nm large) homogeneously distributed on the surface of the films and (e) the optical properties of the films are notably affected by the insertion of Mn and by the temperature of thermal treatment.

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In this work, mixed alkali metaphosphate glasses based on K-Na, Rb-Na, Rb-Li, Cs-Na and Cs-Li combinations were studied by differential scanning calorimetry (DSC), complex impedance spectroscopy, and Raman spectroscopy. DSC analyses show that both the glass transition (T) and melting temperatures (T) exhibit a clear mixed-ion effect. The ionic conductivity shows a strong mixed-ion effect and decreases by more than six orders of magnitude at room temperature for Rb-Na or Cs-Li alkali pairs. This study confirms that the mixed-ion effect may be explained as a natural consequence of random ion mixing because ion transport is favoured between well-matched energy sites and is impeded due to the structural mismatch between neighbouring sites for dissimilar ions.