Materials Literature
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In-situ-AFM-Messungen belegen, dass die Auflösung von Calciumphosphatkristallen in Gegenwart polymerer Additive nach Regeln stattfindet, die typisch für das jeweilige Muster funktioneller Gruppen auf dem Polymer sind. So ergeben Poly(natriumaspartat), Polylysin und Albumine durch unterschiedliches Abtragen der Kristal…
Stern- und Blockpolymere können durch lebende Radikalpolymerisationen hergestellt werden. Aus Lösungen dieser Makromoleküle entstehen beim Gießverfahren unter feuchten Bedingungen isoporöse, honigwabenartige Filme (siehe rasterelektronenmikroskopische Aufnahme). Dabei zeigt sich, dass der Porendurchmesser nicht nur vo…
Photoinduced anisotropy in amorphous selenium ( a-Se) has been studied by in situ x-ray absorption fine structure spectroscopy. It is found that upon irradiation with linearly polarized light the chainlike fragments in a-Se are oriented with their c-axis perpendicular to the polarization plane of the inducing light. T…
The acoustic signal from the sonochemical production of H2O2 in water, as measured by the intensity and the width of the second harmonic, show a sensitive and correlated dependence to the presence of small amounts (millimolar range) of an anionic surfactant (SDS) in water. The graphic shows the link from the ultrasoni…
Two BaxSr1−xO3, films with different contents of Ba (Ba0.25Sr0.75O3 and Ba0.75Sr0.5O3), separated by a MgO film, are used to fabricate planar varactors with low temperature coefficient of capacitance (TCC), high tunability and low losses. The TCC of the varactors are small in the temperature interval between the diele…
The synthesis, crystal structure, and magnetic characterization of a high-spin cluster comprising eight iron ions are presented in this contribution. The cluster has formula [(tacn)6Fe8O2(OH)12Br4.3(ClO4)3.7]·6H2O (Fe8pcl), where tacn is the organic ligand 1,4,7-triazacyclononane. It can be considered a derivative of…
The triple-barrier coupled quantum dots have been fabricated in individual single-wall carbon nanotubes by depositing a narrow SiO2 layer in between metallic source–drain contacts. The current–voltage characteristics at 4.2 K with different gate voltages before the SiO2 deposition have indicated the formation of a sin…
It is well known that chemical etching of strontium titanate (SrTiO3) results in titanium-terminated (B site) surfaces. In this letter, we describe a facile method for generating strontium-terminated surfaces in SrTiO3. We demonstrate that a substrate treatment consisting of a low-power oxygen ashing followed by annea…
Etching edges: In situ measurement by atomic-force microscopy (AFM) is employed to investigate the dissolution of calcium phosphate crystals in the presence of different polymeric additives. The dissolution occurs in a way that is dependent on the pattern of functional groups on each polymer. The influence of poly(sod…
Das größte bisher bekannte Wolframatoarsenat(III), [AsW65O217(H2O)7]26− 1, wurde aus wässriger, saurer Lösung in Form seines Kaliumsalzes in guter Ausbeute isoliert und durch Einkristall-Röntgenstrukturanalyse, 183W-NMR- und FT-IR-Spektroskopie sowie Elementaranalyse charakterisiert. Die kompakte Struktur von 1 mit id…
A series of molybdenum and tungsten organometallic oxides containing [Ru(arene)]2+ units (arene =p-cymene, C6Me6) was obtained by condensation of [[Ru(arene)Cl2]2] with oxomolybdates and oxotungstates in aqueous or nonaqueous solvents. The crystal structures of [[Ru(eta6-C6Me6]]4W4O16], [[Ru(eta6-p-MeC6H4iPr]]4W2O10],…
A new topology within the family of metallohelicates has been revealed by the crystal structure of the complex [Mn3(HL)3] (see picture). The novel oxygen-based pentadentate ligand H3L reacts with Mn(OAc)2 to produce this unique triple-stranded helicate with an unprecedented asymmetric arrangement of the metal ions alo…
We compare the effects of O2, Ar, and H2 gases on the field-emission (FE) properties of single-walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes (MWNTs). We find that H2 and Ar gases do not significantly affect the FE properties of SWNTs or MWNTs. O2 temporarily reduces the FE current and increases the…
Carbon nanotube junctions are of great interest in the fundamental research and nanoelectronic applications. Identical carbon nanotube Y junctions have been successfully synthesized by pyrolysis of methane over cobalt supported on magnesium oxide. The Y junctions have very straight arms with uniform diameters, and the…
Formation and decay of nonbridging oxygen hole centers (NBOHC, an oxygen dangling bond) in SiO2 glasses by F2 excimer laser (7.9 eV) irradiation were in situ analyzed by monitoring 1.9 eV photoluminescence of NBOHC using a pump and probe technique. In wet SiO2, the SiO–H bond was efficiently photolyzed by F2 laser pho…
Bergman cyclization of 2,3-dialkynyl-meso-tetraphenylporphyrins and carbon–carbon bond formation (mediated by 1,4-diradicals) with the adjacent meso-phenyl rings lead to formation of an unprecedented multicarbocycle fused onto the porphyrin periphery. The highly π-extended parent molecules (1; R=Bu, H, Ph) are describ…
Frequency upconversion into green and red luminescence in erbium–ytterbium-codoped phosphate glass pumped with a 970 nm diode laser is presented. The red upconversion emission results from a two-photon excitation process. The green emission results from a two- or three-photon excitation process with the two-photon pro…
An electronic switch at the molecular level has been realized by using a class of ionic compounds of the formula [Co(L)(diox)]Y (L = tetraazamacrocyclic ligand, Y = mononegative anion). Such compounds undergo temperature- and pressure-induced intramolecular one-electron transfer equilibria. The transition temperature…
A method is presented to determine the particle size and internal strain from broadened x-ray peaks obtained on small coherent domains containing dislocations. In contrast with the evaluation techniques applied earlier, the proposed procedure requires only the measurement of a single line profile. It is based on the a…
Using a mean-field equation of state we calculate the density-concentration phase diagrams for a binary mixture of repulsive Gaussian core particles over a range of size ratios. A simple mean-field density functional (DFT) approach, equivalent to the random phase approximation, is used to calculate the surface tension…