Growth and characterization of epitaxial Ti3GeC2 thin films on 4H-SiC(0001)

Epitaxial Ti₃GeC₂ thin films were deposited on 4° off-cut 4H-SiC(0001) using magnetron sputtering from high purity Ti, C, and Ge targets. Scanning electron microscopy and helium ion microscopy show that the Ti₃GeC₂ films grow by lateral step-flow with {112?0} faceting on the SiC surface. Using elastic recoil detection analysis, atomic force microscopy, and X-Ray diffraction the films were found to be substoichiometric in Ge with the presence of small Ge particles at the surface of the film.     

Formation of macrocyclic oligoferrocenes: a matrix-assisted laser desorption/ionization mass spectrometric study

Oligomeric ferrocenes were investigated simultaneously by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOFMS). The oligomers were obtained by the reaction of tetrahydro-4,4,8,8-tetramethyl-4,8-disila-s-indacene-3a,7a-diyldilithium (Li(2)L) with FeCl(2).1.5 THF (THF = tetrahydrofuran). Depending on the reaction conditions up to ten linear-chain and eleven cyclic ferrocene oligomers with masses between 1139 and 5071 Da could be detected unambiguously. The most abundant macrocycles contained ten and seven iron atoms when the reactions were carried out at -20 and 25 degrees C, respectively. The chains had cyclopentadienes as end groups and formally resulted from replacing one iron of a cycle by two hydrogens, which corresponds to a mass difference of 54 Da. Copyright 1999 John Wiley & Sons, Ltd.     

Decoupling of diffusion from structural relaxation and spatial heterogeneity in a supercooled simple liquid

We report a molecular dynamics simulation of a simple monatomic glass-forming liquid. It is shown that transition to deeper minima in the energy landscape under supercooling results in the formation of icosahedrally structured domains with distinctly slow diffusion which grow with cooling in a low-dimensional manner and percolate around T(c), the critical temperature of the mode-coupling theory. Simultaneously, a sharp slowing down of the structural relaxation relative to diffusion is observed. It is concluded that this effect cannot be accounted for by the spatial variation in atomic mobility. The low-dimensional clustering is discussed as a possible mechanism of fragility.