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[en] Clusters properties depends on their size, the transition from the atom / molecule to the bulk is often smooth and the asymptotic behaviour well understood, but for cluster melting is not the case, where irregular fluctuations are found even for clusters containing more than hundred atoms. A method to measure caloric curves for size selected cluster ions is provided. A plot of the cluster energy as a function of cluster temperature gives the caloric curve and contains all its basic thermodynamic properties. The method consists of two steps: in the first, sodium clusters ions are produced and thermalized. The heat bath was a helium gas of known temperature T, where clusters make so many collisions that they reach thermal equilibrium. Then, the thermalized clusters are extracted, transferred to high vacuum, and mass analysed. In the second step, the internal dominantly vibrational energy E of the cluster is measured by a photofragmentation technique, knowing E and T, the caloric curve E= E(T) can be plotted. As an example the Na ₁₃₉⁺ and Na⁺_n study is presented. (nevyjel)

[en] During the post-annealing and cooling process of CoSb₃ thin films deposited on thermally oxidized Si(100) substrates, cracks occur at the surface of the films, which can be caused by the difference in thermal expansion coefficient of the substrate and the film. To investigate the crack formation, 40-nm-thick CoSb₃ films were deposited at room temperature under ultra-high vacuum (UHV) conditions onto various substrates, exhibiting different thermal expansion coefficients (2 x 10^-6 to 12 x 10^-6 K^-1). All samples were post-annealed in UHV at 500 C for 1 h. The composition of the films was verified by Rutherford backscattering spectrometry. The phase formation and elastic stress of the films were analyzed by X-ray diffraction, confirming the formation of the desired skutterudite phase, while the individual grains were studied by electron backscatter diffraction. In addition, the surface morphology and the roughness of the films were investigated by atomic force microscopy. For substrates with a thermal expansion coefficient between 9 x 10^-6 and 11 x 10^-6 K^-1, crack formation can be prevented and a minimum in roughness was found, resulting also in a minimal value of the electrical resistivity. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[en] L1₀ ordered FePt films with (0 0 1) texture and out-of-plane magnetic easy axis were fabricated by rapid thermal annealing of chemically disordered FePt thin films grown on amorphous SiO₂ substrates. While keeping the annealing temperature fixed at 800 deg. C, the influence of the annealing time was investigated in the regime between 5 and 300 s. The evolution of the a and c lattice parameters indicates that the in-plane strain is a key factor for the formation of the (0 0 1) texture. A large tetragonal distortion is found after an annealing time of 5 s whereas a relaxation of the lattice parameters towards bulk values is found for longer annealing times. The dependence of the magnetic properties on the annealing time will be discussed with respect to the observed variation of the structure and morphology of the annealed FePt films.

[en] Synchrotron X-ray diffraction analysis of three-dimensional residual stress fields in laser-pulsed uncoated and CrN-coated steels was performed by a combination of two complementary synchrotron approaches. In the uncoated steel, the measurements revealed crater-like tensile stress distributions close to thermal cracks. For the coated samples, a regular Gaussian distribution was observed for steel whereby a cracking occurs in CrN as a consequence of steel buckling. The data also revealed the mechanism by which hard coatings protect steel from thermal fatigue.