Materials Literature
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Compounding extruders are still designed based on experience and time-consuming experimental examinations. This work investigates the morphology development of incompatible polyblends along a mixing zone at the end of a corotating twin-screw extruder. During the process, the samples are taken from the running extruder…
Concerted cleavage of two C−C single bonds provides the basis for a novel concept for the storage and release of electrons. Electron transfer, mediated by metal ions, occurs between the cyclopropyl ring of a Ni porphyrinogen and the interligand C−C bond of a bis(Ni-salophen) complex (see scheme).
Reaction of the thiol-terminated fourth-generation dendrimer 2-G4 (96 SH groups) with the gold cluster compound Au55(PPh3)12Cl6 in a 3:1 molar ratio in dichloromethane results in the formation of bare Au55 clusters. The cuboctahedrally shaped Au55 particles coalesce to well-formed microcrystals (Au55) infinity. The ro…
The by no means trivial, solid-state reaction for the condensation of {(Mo)Mo5}12Fe30 giant spheres commences through the water ligands and leads to oxo (or hydroxo) bridging. As the discrete icosahedral units approach each other, their oxygen atom bridges ultimately form covalent bonds (Fe−Fe 3.79 Å, see picture) to…
Es wird eine chemische Betrachtung spinmagnetischer Phänomene in abgeschlossenen (Atome und Moleküle) und unendlich großen Systemen (Übergangsmetalle und ihre Legierungen) vorgestellt, die auf den Konzepten von Bindung und elektronischer Abschirmung basiert. Der Ansatz soll als halbquantitative Richtschnur für die Syn…
The role of the ligand's structure and absolute configuration in the supramolecular chirality induction in achiral bis(zinc porphyrin) has been studied. The amines with bulkier substituents resulted in stronger CD signals due to increased helical displacement in the anti conformer. All the amines with an R absolute co…
Thirty electrons are frozen on the O = Mo(H2O) groups which function as spacer units between the {(Mo)Mo5} building units of the giant {Mo102} sphere 1 (the picture shows a wireframe representation in which the spacer units are represented as a darker shade).
A detailed multifrequency high-field-high-frequency EPR (95-285 GHz) study has been performed on the single-molecule magnet of formula [Fe8O2(OH)12(tacn)6]Br8 x 9H2O, in which tacn = 1,4,7-triazacyclononane. Polycrystalline powder spectra have allowed the estimation of the zero-field splitting parameters up to fourth…
Silole-2,5-diboronic acid derivatives 1 serve as new precursors for silole-based π-conjugated polymers 2. The Suzuki–Miyaura coupling of the diboronic acids with 2,5-bis(bromothienyl)silole affords silole–thiophene alternating copolymers, which have a particularly narrow band gap owing to the effects of the ring silic…
Architecture in minature: Fréchet-type monodendrons functionalized on their periphery with the 3,4-bis(n-dodecan-1-yloxy)benzyl ether minidendron exhibit flat tapered (at generations two (G2) and three (G3)), disclike (G4), and conical (G5) shapes that self-assemble into cylindrical (G2–4) and spherical (G5) supramole…
Complicated, alternating ferromagnetic/antiferromagnetic interactions in homometallic, one-dimensional MnII-azido systems permit an unprecedented ferrimagnetic response. One new kind of ferrimagnet with a surprising ferrimagnetic behavior in a system with ground state ST = 0 (see picture) was observed and related to t…
The partitioning of Zn to the pyrophyllite surface was studied as a function of surface loading for periods up to 4 months. Examination of the reaction products using X-ray absorption fine structure spectroscopy (XAFS) indicated the formation of a Zn precipitate at each surface loading. Comparison of the local structu…
The world record in ground state spin value “S = 51/2” belongs to a ferromagnetically coupled, cyano-bridged pentadecanuclear Mn cluster (see picture). This molecule has 51 unpaired electrons. Magnetic dipole–dipole interactions together with exchange interactions resulting from the specific three dimensional crystal…
Recent high pressure work has suggested that elemental barium forms a high pressure self-hosting structure (Ba IV) involving two `types' of barium atom. Uniquely among reported elemental structures it cannot be described by a single crystalline lattice, instead involving two interpenetrating incommensurate lattices. I…
We examine the response of a soft ferromagnetic film to an in-plane applied magnetic field. Our theory, based on asymptotic analysis of the micromagnetic energy in the thin-film limit, proceeds in two steps: first we determine the magnetic charge density by solving a convex variational problem; then we construct an as…
We perform experiments on thin-film diaphragms to show that the folding patterns of anisotropically compressed diaphragms are strikingly different from those of isotropically compressed ones. We then use a simple von Karman model to relate the overall features of these folding patterns to the underlying energetics. We…
A method is developed which allows to determine the first-order and the second-order magnetoelastic coefficients of a magnetic bulk material from the ab-initio calculation of the magnetocrystalline anisotropy energy as function of a prestrain. Excplicit results are given for bcc Fe, and they agree well with experiment…
A numerical investigation of grain-boundary (GB) grooving by means of the Level Set (LS) method is carried out. GB grooving is emerging as a key element of electromigration drift in polycrystalline microelectronic interconnects, as evidenced by a number of recent studies. The purpose of the present study is to provide…
A chemical view of spin magnetic phenomena in finite (atoms and molecules) and infinite (transition metals and their alloys) systems using the concepts of bonding and electronic shielding is presented. The concept is intended to serve as a semiquantitative signpost for the synthesis of new ferromagnets. After a concis…
The effect is treated of the space charge field and of the crystallite size on the properties of ferroceramics of different compositions. The established qualitative correlation between the structure and electrophysical parameters, the crystallite size, and the space charge field may be useful in designing ferropiezoc…