Materials Literature
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The valence- and conduction-band electronic densities of states (DOSs) in amorphous (a-) GeSe and GeTe were investigated by means of ultraviolet photoemission and inverse-photoemission spectroscopy (UPS and IPES), respectively. The UPS spectra for both a-GeSe and a-GeTe are very similar to those obtained in previous e…
Pore growth on n-type GaAs (100) can be initiated in 1 M HCl solution by electrochemical polarization of the material anodic to a critical potential value—the pore formation potential (PFP). At surface defects, however, the PFP is significantly lower (shifted cathodically). Focused ion beam, implantation of Si++ was u…
The electrostrictive coefficients of prototype cubic phase of PbMg1/3Nb2/3O3 are studied using a high-resolution neutron powder diffraction experiment. The key idea of the approach is to “eliminate” from the material the inhomogeneity related to the presence of the double-phase mixture “polar regions/nonpolar matrix,”…
C -axis oriented La0.7Sr0.3MnO3−δ (LSMO) films were fabricated on the top of SrTiO3/YBa2Cu3O7 grown on MgO (001) substrates. From x-ray φ-scan and planar transmission electron microscopy measurements, the LSMO layer in the LSMO/SrTiO3/YBa2Cu3O7/MgO heterostructure is found to have coherent in-plane grain boundaries wi…
Die pH-Wert-abhängige Selbstkondensation von [Mo2S2O2]2+-Komplexfragmenten führt zum rechts dargestellten radförmigen Mo12-Cluster (Kugel-Stab-Modell, große Kugeln: S, mittlere Kugeln: O, kleine Kugeln: Mo). Eine Übertragung dieses Synthesetyps auf andere Vorstufen könnte den Zugang zu weiteren Polyoxothiometallaten m…
Kondensierte Singulett-Elektronenpaare müssen vorliegen, damit Quecksilber supraleitend wird. Diese und andere Zusammenhänge zwischen Supraleitung und chemischer Bindung wurden jetzt an dem Metall berechnet, an dem die Supraleitung auch entdeckt wurde.
The electrical resistivity and temperature coefficient of resistivity (TCR) of Cu and Nb thin films have been measured over a range of layer thicknesses between 5.6 nm and 1106 nm. The structure of the films has been characterized using transmission electron microscopy (TEM) and x-ray diffraction. The experimental res…
Decidedly higher clearing temperatures and often also broader mesophases are exhibited by axially fluorinated cyclohexane derivatives 1 and 2 relative to their nonfluorinated analogues. A convenient method for the multigram synthesis of 1 and 2, which represent a promising new type of liquid crystals with positive or…
A scheme for calculating the complex self-energy of electrons moving in a real metal surface region is proposed. The approach is based on a quantum formula that uses a Drude-Lindhard model bulk dielectric function for describing free-electron metal. The experimental energy-loss function is fitted to a finite sum of th…
Thin-film lead–zirconate–titanate (PZT) capacitors with composition gradients normal to the substrate were fabricated via a novel technique using pulsed laser deposition. These capacitors exhibited large polarization offsets when driven by an alternating electric field. The direction of the offsets depended on the dir…
The low-field magnetoresistance and the magnetization of ceramic oxides have been studied as a function of the grain size. It is shown that these ceramics become magnetically harder when reducing the particle size, exhibiting large magnetic anisotropy that also increases when reducing the grain size. In concomitance w…
Thin films of AgInO2 were prepared to find a transparent and n-type conducting oxide with a delafossite structure. This is a candidate material for fabricating a pn junction with the recently found p type conducting and transparent CuAlO2 delafossite. Nondoped and 5% Sn-doped thin films were deposited on a silica glas…
On the basis of a quantum approach, the formula for the complex self-energy, and hence also that for the energy-loss cross-section, are derived for fast electrons penetrating through the surface from the interior of a solid. Both the angular and depth dependence are included in the expression. Use of a Drude-Lindhard…
Transmission electron microscopy and neutron diffraction have been used to characterize ceramics and single crystals from the rhombohedral region of the ( x = 0.06-0.45) phase diagram. Electron diffraction patterns showed the existence of superlattice reflections of the type , where h = k = l , and , which are not obs…
Homobimetallic macrocycles are prepared from flexible ligands in high yield by means of a new and general synthetic strategy called the "weak-link approach" [Eq. (a)]. Small aromatic molecules can be aligned inside the cage based on their interactions with the two Rh centers of the macrocycle.
A quantitative comparison of the pore space geometry for three natural sandstones is presented. The comparison is based on local porosity theory which provides a geometric characterization of stochastic microstructures. The characterization focusses on porosity and connectivity fluctuations. Porosity fluctuations are…
Ferroelectric Bi4Ti3O12 ceramics have been prepared by the method of reactive sintering. The ceramics exhibit good ferroelectric properties with a remanent polarization Pr=5.5×10−2 C/m2 and a coercive field Ec=3MV/m. High resolution x-ray photoelectron spectra of the atomic constituents of Bi4Ti3O12 were recorded. The…
Charge ordering and orbital ordering in ${\mathrm{La}}_{0.5}{\mathrm{Sr}}_{1.5}{\mathrm{MnO}}_{4}$ have been investigated by using synchrotron x-ray diffraction. The alternating pattern of ${\mathrm{Mn}}^{3+}/{\mathrm{Mn}}^{4+}$ in real space is observed directly by making use of their anomalous dispersion. The first…
A phenomenological thermodynamic theory of ferroelectric thin films epitaxially grown on cubic substrates is developed using a new form of the thermodynamic potential, which corresponds to the actual mechanical boundary conditions of the problem. For single-domain ${\mathrm{BaTiO}}_{3}$ and ${\mathrm{PbTiO}}_{3}$ film…
A new exciting interdisciplinary research field has evolved following the discovery that conjugated polymers can emit light when put into light-emitting diodes. A myriad of light-emitting polymers (examples of which are shown below) shining in various colors have been developed through chemical intuition and structura…