Materials Literature
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Three novel vanadogermanate cluster anions have been synthesized by hydrothermal reactions. The cluster anions are derived from the (V(18)O(42)) Keggin cluster shell by substitution of V=O(2+) "caps" by Ge(2)O(OH)(2)(4+) species. In Cs(8)[Ge(4)V(16)O(42)(OH)(4)].4.7H(2)O, 1, (monoclinic, space group C2/c (No. 15), Z =…
The strain state of epitaxial La0.5Sr0.5MnO3 thin films on BaTiO3 are dynamically tuned by temperature and substrate bias. The resistivity of the La0.5Sr0.5MnO3 thin films is particularly sensitive to changes in structure. Fractional changes in magnetization and resistivity as a function of temperature reveal a direct…
The electronic spectrum of CdS colloidal quantum dots (QDs) with a radius of 1.0−2.3 nm is studied by low-temperature photoluminescence excitation spectroscopy. CdS QDs are found to exhibit a resonant Stokes shift of ∼20−70 meV, which is ∼4 times larger than similarly sized CdSe QDs. This effect can be reproduced by a…
Plastic deformation of nanocrystalline Fe was investigated by nanoindentation. Samples, synthesized by mechanical attrition, consisted of powder particles with diameters greater than 30 μm. The average grain diameters within the particles of different samples ranged from 10 nm to 10 μm. To avoid potential artifacts, s…
Abstract The kinetics of the thermal degradation and thermal stability of conductive silicone rubber filled with conductive carbon black was investigated by thermogravimetric analysis in a flowing nitrogen atmosphere at a heating rate of 5°C/min. The rate parameters were evaluated by the method of Freeman–Carroll. The…
We have measured the composition and frequency-dependent complex effective permittivities and permeabilities in zero applied field of a series of ZnO and ferrimagnetic γ-Fe2 O3 composites prepared by powder pressing. The overall features of the room temperature electromagnetic properties of these diluted magnetic semi…
Abstract The thermal degradation kinetics of poly(3‐hydroxybutyrate) (PHB) and poly(3‐hydroxybutyrate‐ co ‐3‐hydroxyvalerate) [poly(HB–HV)] under nitrogen was studied by thermogravimetry (TG). The results show that the thermal degradation temperatures ( T o , T p , and T f ) increased with an increasing heating rate (…
The crystal structure of the bifunctional enzyme 4-hydroxy-2-ketovalerate aldolase (DmpG)/acylating acetaldehyde dehydrogenase (DmpF), which is involved in the bacterial degradation of toxic aromatic compounds, has been determined by multiwavelength anomalous dispersion (MAD) techniques and refined to 1.7-A resolution…
The orientation dependence of piezoelectric properties has been calculated for 0.67Pb(Mn1/3Nb2/3)O3–0.33PbTiO3 (PMN–33%PT) single-domain crystals based on the measured full matrix properties. It is found that the maximum d33*=2411 pC/N and k33*=0.94 occur, respectively, in directions 63.0° and 70.8° from the spontaneo…
The effect of antisite (AS) defects and electron doping on the ferromagnetic--paramagnetic (FM-PM) transition of ${\mathrm{Sr}}_{2}{\mathrm{FeMoO}}_{6}$ (SFMO) double perovskite has been studied. From a detailed analysis of the magnetization curves across the FM-PM transition we conclude that AS defects decrease the a…
The guidance conditions of modes with both real and imaginary transverse wave numbers inside a dielectric slab with negative permittivity and permeability are solved. We show that for real transverse wave numbers, cutoffs exist for all modes, unlike in conventional media where the first even mode is always propagating…
Recently, a perovskite solid-solution ((1−x)BiScO3−(x)PbTiO3) with superior electromechanical properties than PbZrO3−PbTiO3 (PZT) ceramics has been discovered. The system has a morphotropic phase boundary (MPB) between ferroelectric rhombohedral (R) and tetragonal (T) symmetries similar to PZT but the underlying domai…
We present the structure of anhydrous sodium carbonate at room temperature (phase gamma) and 110 K (phase delta) based on single-crystal X-ray diffraction data. The incommensurate phase gamma was determined almost 30 years ago in the harmonic approximation using one modulation wave and first-order satellites. In our w…
We introduce an algorithm for treating growth on surfaces which combines important features of continuum methods (such as the level-set method) and Kinetic Monte Carlo (KMC) simulations. We treat the motion of adatoms in continuum theory, but attach them to islands one atom at a time. The technique is borrowed from th…
Similarities between alkali gases in optical lattices with non-integer occupation of the lattice sites and quantum crystals are explored. The analogy with the vacancy liquid (VL) provides an alternative explanation to the Mott transition for the recent experiment on the phase transition in the lattice. The VL can unde…
The magnetotransport properties of single crystals of the highly anisotropic layered metal LaSb2 are reported in magnetic fields up to 45 T with fields oriented both parallel and perpendicular to the layers. Below 10 K the perpendicular magnetoresistance of LaSb2 becomes temperature independent and is characterized by…
The nucleation of a droplet of stable cylinder phase from a metastable lamellar phase is examined within the single-mode approximation to the mean-field Landau–Brazovskii model for diblock copolymer melts. By employing a variational ansatz for the droplet interfacial profile, an analytic expression for the interfacial…
Magnetization properties of magnetic nanowire arrays are studied on various ferromagnetic materials grown in anodic alumina (alumite) and track etched polycarbonate (PCTE) membranes by pulsed electrodeposition. Magnetization curves were measured as functions of wire material, field orientation, and wire length. The co…
The crystal structure of a polymorph of copper phthalocyanine (CuPc) grown on a KCl substrate is redetermined by transmission electron diffraction. It has a triclinic unit cell containing one molecule; the crystal does not have a herringbone-type molecular arrangement, which is a common packing mode of planar phthaloc…
In the present work we analyze the influence of the charge-ordering on the magnetocaloric effect of Pr$_{1-x}$Ca$_x$MnO$_3$ manganites. The results for the samples with $x<$0.30 present the usual ferromagnetic behavior, peaking at the Curie temperature T$_C$. In contrast, for the samples above the onset concentration…