Comment on "Melting of Isolated Tin Nanoparticles"

Comment on the paper of T.Bachels, H. J. G\"{u}ntherodt and R.Sch\"{a}fer : "Melting of Isolated Tin Nanoparticles".Comment: Accepted for publication in Phys. Rev. Let

Intrinsic defects and their influence on the chemical and optical properties of TiO2x films

International audienceIn this work, TiO2 films produced by rf sputtering of a TiO2 target in argon and argon–oxygen plasmas were studied. The oxygen content in the feed gas was varied in a range 3–20%. The chemical composition and structure of films were characterized by Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy (XPS) and x-ray diffraction. Important information about the intrinsic defects of the films and their effects on the optical properties as well as a scheme of the energy band structure of the films could be derived from a combined use of optical spectroscopy and XPS

Premelting of Thin Wires

Recent work has raised considerable interest on the nature of thin metallic wires. We have investigated the melting behavior of thin cylindrical Pb wires with the axis along a (110) direction, using molecular dynamics and a well-tested many-body potential. We find that---in analogy with cluster melting---the melting temperature $T_m (R)$ of a wire with radius $R$ is lower than that of a bulk solid, $T_m^b$, by $T_m (R) = T_m^b -c/R$. Surface melting effects, with formation of a thin skin of highly diffusive atoms at the wire surface, is observed. The diffusivity is lower where the wire surface has a flat, local (111) orientation, and higher at (110) and (100) rounded areas. The possible relevance to recent results on non-rupturing thin necks between an STM tip and a warm surface is addressed.Comment: 10 pages, 4 postscript figures are appended, RevTeX, SISSA Ref. 131/94/CM/S

Capacitance-conductance investigation on the phase transitions in Ga nanoparticles

We have reported on coupled capacitance-conductance measurements on Ga nanoparticles embedded in vitreous matrices. The melting of nanoparticles was clearly detected as an abrupt increase in the capacitance vs. temperature scans. The influence of the embedding matrix and of the frequency of the applied field on the dielectric response was checked. The presence of a hysteresis cycle between melting and solidification has been detected. The technique allows the identification of the various solid phases of confined Ga

Optical absorption in ZrO2-x-C nanocomposite films on polymer substrates: application of an effective medium theory

Films consisting of amorphous carbon dispersed in tetragonal nanocrystalline zirconia were characterized for their optical properties by reflectance measurements. The optical constants of each component of the composite have been extracted; the experimental reflectance spectra have been fitted to Maxwell-Garnett effective medium theory, leading to the effective dielectric constants of the film. Absorption is characterized by the band gap, the energy and lifetime of the optical transition of the absorbing carbon phase. These parameters are deduced from the imaginary part of the dielectric function using Tauc-Lorentz model (TL) and from the extinction coefficient using Forouhi-Bloomer model (FB) in which an energy dependence of the matrix element of the transition has been introduced. Furthermore, the energies of the peak transition and the maximum of the extinction coefficient are so similar that they prove the self-consistency of the modified-FB model applied to the amorphous carbon phase of the composite films

Interaction of liquid droplets with a polarized polymer: influence of its polarization [Influence de la polarisation d'un polymère sur ses interactions avec une goutte de liquide suspendue ou posée]

International audienceLiquid droplets having different polar natures were located above a polarized substrate; their shapes revealed the influence of the polarization state of the substrate. From the contact angle of a resting droplet on this substrate, one deduces the effect of a previous chemical treatment applied to the surface of the substrate