ZnS:Mn2+ nanoparticles were synthesized via a wet chemical method with L-cysteine as the stabilizing agent. The obtained aqueous dispersions show an orange luminescence, which is typical for the 4T1 → 6A1 transition within the Mn2+ d-orbitals. The fluorescence quantum yield has been determined with quinine sulphate as a dye reference. It can be increased after formation of a SiO2 shell around the particles by a factor of three. The particle size was determined with transmission electron microscopy (TEM), X-ray diffraction and PCS measurements.

Are the arc components in a locally compact group Borel subsets? An affirmative answer is provide for locally compact groups satisfying the First Axiom of Count-ability. For general locally compact groups the question is reduced to compact connected Abelian groups. In certain models of set theory the answer is negative.

Significant effort to develop a robust rechargeable battery has been put in the past two decades. The efforts were mainly focused on developing rechargeable battery systems which exhibit high capacity, long cycle life and high discharge rate capabilities. LiMn2O4 based cathodes have been researched extensively as they are not only economical but also environmentally desirable. Research includes composition and doping variation, formation of novel phases and microstructural tailoring, but none of the material modifications have successfully satisfied all the above mentioned performance criteria. In this paper we show a correlation between processing parameters, microstructure and electrochemical performance of Li-Mn-O cathode films. In addition we discuss the formation of metastable oxygen-rich lithium manganospinels, using a unique ultraviolet assisted deposition process. These defective films exhibit high capacity (> 230 mAh/gm), long cycle life (less than 0.05 % capacity loss per cycle for the first 700 cycles), and high discharge rates (> 25 C for 25 % capacity loss). The long cycle life and high capacity was attributed to the ability to cycle the Mn+ valence to less than 3.5 without onset of Jahn-Teller structural transformation, while the high discharge rate was attributed to the extremely high diffusivity of Li+ in the defective Li1-δMn2-2δO4 phase.

The deposition rate of titanium films plays a determining role for possible fabrication schemes of metallic SET structures. Depending on this rate the resistivities display a striking difference in their temperature dependence which is attributed to their different crystal structure as analyzed by transmission electron-beam microscopy. In addition a sharp rise in resistivity occurs below a critical thickness in films deposited at slow rates. This sharp increase can be used in combination with a step induced thinning to form tunnel junctions for single electron transistor structures.

Epitaxial ReSi1.75 thin films of variable thickness between 15nm and 150nm have been prepared in an one step process by Facing Target Sputtering (FTS) onto heated (100) and (111)Si and SOS wafers. The epitaxial relations and film structure have been investigated by Xray diffraction and transmission electron microscopy. Epitaxial growth was found at a substrate temperature of 1070K. Thermoelectric properties were measured between 100K and 450K and compared to the transport behavior of bulk ReSi1.75 and polycrystalline films. A distinct dependence of both the conductivity and thermopower was found on the film thickness, on unintentional doping and on the film structure. The results show that epitaxial ReSi1.75 films prepared by FTS can be a basis for further investigations of thermoelectric silicide/silicon multilayers.

The electrical conductivity of 3Y-TZP ceramics containing SiO2 and Al2O3 has been investigated by complex impedance spectroscopy between 500 and 1270 K. At low temperatures, the total electrical conductivity is suppressed by the grain boundary glass films. The equilibrium thickness of intergranular films is 1-2 nm, as derived using the “brick-layer” model and measured by HRTEM. A change in the slope of the conductivity Arrhenius plots occurs at the characteristic temperature Tb at which the macroscopic grain boundary resistivity has the same value as the resistivity of the grains. The temperature dependence of the conductivity is discussed in terms of a series combination of RC elements.

The synthesis of silicon nitride powder by the reaction between silica, carbon and nitrogen is the economically most interesting route. Only this route makes possible the use of very cheap raw materials as well as the use of a simple production process. On the other side, the properties of the powders are within the limit of the technical requirements of the ceramic part manufacturer. The aim of this paper is to show that an optimized carbothermal Si3N4 powder synthesis leads to a product which fulfills the economical (low price) as well as the technical requirements. After a short introduction regarding the economical requirements, an overview of the carbothermal synthesis will be given. The influence of raw material, conditions of synthesis and removal of excess carbon on the powder properties will be discussed. Also, the properties of the powder as well as the sintering behaviour of Si3Ns4 powders, produced by Si-direct nitridation, Si-diimide process and the carbothermal route, will be compared in detail.

A (local) Lie loop is a real analytic manifold M with a base point e and three analytic functions (x, y) → x° y, x\y, x/y: M × M → M (respectively, U × U → M for an open neighbourhood U of e in M) such that the following conditions are satisfied: (i) x ° e = e ° x = e, (ii) x ° (x\y) = y, and (iii) (x/y)° y = x for all x, y ε M (respectively, U). If the multiplication ° is associative, then M is a (local) Lie group. The tangent vector space L(M) in e is equipped with an anticommutative bilinear operation (X, Y) →[X, Y] and a trilinear operation (X, Y, Z) →〈X, Y, Z〉. These are defined as follows: Let B be a convex symmetric open neighbourhood of 0 in L(M) such that the exponential function maps B diffeomorphically onto an open neighbourhood V of e in M and transport the operation ° into L(M) by defining X ° Y = (exp|B)−1((exp X)° (exp Y)) for X and Y in a neighbourhood C of 0 in B such that (exp C) ° (exp C) ⊂ V. Similarly, we transport / and \.

In the category of locally compact groups not all families of groups have a product. Precisely which families do have a product and a description of the product is a corollary of the main theorem proved here. In the category of locally compact abelian groups a family {Gj; j ∈ J} has a product if and only if all but a finite number of the Gj are of the form Kj × Dj, where Kj is a compact group and Dj is a discrete torsion free group. Dualizing identifies the families having coproducts in the category of locally compact abelian groups and so answers a question of Z. Semadeni.

We propose an exceptionally short and effortless approach to the fundamental facts of the representation theory of compact groups on Hilbert spaces and expand our methods to prove some generalizations concerning representations on arbitrary locally convex vector spaces.