Materials Literature
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Resistivity (15 - 710 K), magnetization (80 - 723 K), and calorimetric (200 - 623 K) measurements on have shown evidence for the formation of Jahn - Teller (JT) polarons below . Above 560 K, activated conduction with is observed and shows Curie - Weiss behaviour. Over the temperature range 270 - 340 K, the conductivit…
Model compounds for silica surfaces modified with metal complexes are provided by the mononuclear anionic diperoxo species 1 and the dinuclear complex anions 2 (M = Mo, W). They were obtained in fair to nearly quantitative yields by the reactions of Ph3SiOH and [Ph2Si(OH)]2O, respectively, with an aqueous solution of…
We report an ellipsometry study of the wetting of hexane on water. By adding salt to the water, we are able to tune the Hamaker constant of this system. This allows us to demonstrate, for the first time, that two rather than one wetting transitions can exist in a single system. Upon increasing the temperature, a disco…
The cold-cathode electron emission properties of amorphous tetrahedral diamondlike carbon are promising for flat-panel display and vacuum microelectronics technologies. The onset of electron emission is, typically, preceded by “conditioning” where the material is stressed by an applied electric field. To simulate cond…
Nonscattering glasses that are indefinitely stable with respect to crystallization can be prepared from the title compounds. In these solid solutions, the dendritic substituents effectively suppress interactions between the phthalocyanine units (see the structure depicted on the right).
The ruffle of the porphyrin increases with the number of meso substituents. (Octaethylporphyrin)nickel(II) undergoes nucleophilic substitution reactions upon treatment with alkylating reagents such as butyllithium, hydrolysis with water, and oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone [DDQ; Eq. (a)]. Alky…
We report a principle that allows one to write visible light emitting silicon patterns of arbitrary shape down to the submicrometer scale. We demonstrate that porous Si growth can electrochemically be initiated preferentially at surface defects created in an $n$-type Si substrate by ${\mathrm{Si}}^{++}$ focused ion be…
Silver nanocrystals have been grown on Xe buffer layers at 50 K. These 3D nanocrystals are delivered to $\mathrm{Si}(111)\ensuremath{-}(7\ifmmode\times\else\texttimes\fi{}7)$ surfaces when the Xe layer is desorbed, but the density observed on the surface depends strongly on the buffer layer thickness. This dependence…
A new coordination mode for the porphyrin ligand is found in [B2O2(BCl3)2(tpClpp)] (tpClpp=dianion of 5,10,15,20-tetra-p-chlorophenylporphyrin; the p-chlorophenyl groups are omitted for clarity in the picture shown on the right). This complex contains a four-membered B2O2 ring in the cavity of the ligand. The two boro…
Der bislang größte anorganische Cluster [(MoO3)176(H2O)80H32](2±2)− 1 (im Bild rechts sind die Mo-O-Polyeder gezeigt), der jetzt röntgenstrukturanalytisch charakterisiert wurde, weist neben einem Hohlraum mit einem Durchmesser von 2.3 nm bemerkenswerterweise die Stöchiometrie eines reduzierten, protonierten und hydrat…
Simply mixing solutions of the title compound 1 and tetrathiafulvene (TTF) in acetonitrile provides the charge-transfer complex 2. Here, 1 functions as a novel electron acceptor and is present in the complex as a radical anion. An electrical conductivity of up to 3 S cm−1 was determined for 2 with a two-point powder m…
We have investigated the formation of polymer walls for high polymer content liquid crystal (LC) formulations, using a patterned electric field to induce phase separation. The effect of this field on the phase separation temperature of a LC/monomer mixture is studied as a function of the photopolymerizable monomer con…
Deposition of individual single-wall carbon nanotubes over multiple (up to seven) Pt nanoelectrodes is realized. Two-probe and four-probe transport measurements between adjacent pairs of electrodes show similar but not identical single-electron Coulomb charging signatures at low temperatures. The observations indicate…
High-sensitivity femtosecond transient absorption is applied to directly measure the population-depopulation dynamics of the lowest ( $1S$) and the first excited ( $1P$) electron states in CdSe nanocrystals (NC's) of different radii with $1S$--- $1P$ energy separation up to 16 longitudinal optical phonon energies. Ins…
Copper(II)-containing nickel(II) hydroxide particles, i.e., α-Ni 1 - x Cu x (OH) 2 (0 < x ≤ 0.4), have been prepared by aging 0.5 mol dm - 3 urea, Ni(NO 3 ) 2, and Cu(NO 3 ) 2 solutions at 363 K. After 3 h, coprecipitation is almost complete. The formed solids, characterized by powder X-ray diffraction, scanning elect…
The electrical transport properties, such as direct current (dc) electrical conductivity (σ), dielectric constant (ε′), and dc current–time characteristics of unirradiated and γ-irradiated pure and NiCl2-doped PVA were studied in the temperature range of 26–155°C. Quantitative analysis was carried out to determine the…
The reaction between Ru(2)(O(2)CMe)(4)Cl and Hadmp (Hadmp = 2-amino-4,6-dimethylpyridine) under different conditions has been investigated. By conducting the reaction in a methanol solution at room temperature the product obtained was Ru(2)(admp)(O(2)CMe)(3)Cl (1). In a melt reaction at 65 degrees C the product isolat…
The reaction of [Fe(salen)](+) and {A(3)[Fe(CN)(6)]} (A = NEt(4), K), depending on the countercation A(+) and on the reaction solvent, led to [(NEt(4)){Fe(salen)}(2){Fe(CN)(6)}](n)(), 4, and [{Fe(salen)}(3){Fe(CN)(6)}(MeOH)(2)](n)().3nH(2)O, 5 [NEt(4) = tetraethylammonium cation, salen = N, N'-ethylenebis(salicylidene…
A mathematical model for solid-state polymerization of poly(ethylene terephthalate) was developed. The effects of temperature and chain entanglement on chain mobility were considered to estimate the rate constants of chemical reactions. The diffusivities of volatile byproducts could be determined using the free volume…
New types of ecologically friendly polymer flame-retardant systems were proposed for Nylon 6,6 and polypropylene [high temperature polymer–organic char former, poly(vinyl alcohol), and silicon–inorganic system]. These systems can act in condensed and gaseous phases. The cone calorimeter and LOI tests indicated the imp…