We have studied SnOx nanoparticles fabricated by gas-phase condensation and in-flight sintering using Raman and photoluminescence (PL) spectroscopy. We are able to identify various vibrational states of the rutile phase of the SnOx crystal. By thorough analysis of the vibrational modes, we are able to determine the bond lengths of the O–O and Sn–O bonds for the substoichiometric SnO1.5, leading, together with x-ray diffraction data, to a full characterization of the SnO1.5 lattice. In absorption and photoluminescence spectra, we observe a finite density of states inside the band gap due to oxygen vacancies, giving rise to a midgap luminescence peak. Our results suggest that the defect related luminescence efficiency is limited by nonradiative recombination processes and by the oxygen vacancy density. We therefore conclude that the PL intensity has a maximum around a stoichiometry of SnO1.7.
Iron nanoparticles with a diameter of 35 nm are synthesized by the thermal decomposition of iron
pentacarbonyl in a hot wall reactor. The particles are ferromagnetic and single magnetic domain.
The magnetic forces between the particles cause the formation of iron nanowires of up to
300 µm
in length. Morphological characterization using high resolution transmission electron
microscopy indicates an oxidic shell with a thickness of 3–4 nm. The electrical properties of
single chains are investigated under air using impedance spectroscopy (IS). It is found that
the conductivity of the iron is in the same range as that of the bulk material.
Temperature dependent measurements on iron nanochain powders performed under
H2-atmosphere reveal strong sintering effects and a transition into iron.
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