Some physical properties of boron sillenite: Bi24.5BO38.25

Large single crystals (≈1cm³) of the incongruently melting boron sillenite Bi_24.5BO_38.25 (space group I23 ) have been grown by the TSSG method with a high crystalline quality. Specimens from nearly inclusion‐free crystals were the basis for measurements of such physical properties like the dispersion of the refractive indices, the optical rotatory dispersion, elasticity as well as thermal expansion. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Zur Abbildung des Feldverlaufs an hochohmigen GaAs-Proben mit der Elektronenmikrosonde

It is shown that electron scanning microscopy investigations of high ohmic GaAs samples with subthreshold working provide useful results of the illustration of the surface potential characterizing the quality of the contacts and the sample homogenity.     

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The lattice parameters of K2SnCl6 at low temperatures determined by high resolution single crystal X-ray diffraction

The temperature dependence of lattice parameters of K₂SnCl₆ was measured in the temperature range 300 K>T>240 K by means of high resolution single crystal X-ray diffraction experiments. The cubic phase ($\text{a=9.986(2)}\text{A}\text{?}\text{,}\text{Z}\text{=4,}\text{T}\text{=280 K}$) was confirmed, whereas in disagreement to earlier authors the intermediate phase was proved to be orthorhombic ($\text{a}\text{=9.966(2)}\text{A}\text{?}\text{, (}\text{b}\text{=9.948(2)}\text{A}\text{?}\text{,}\text{c}\text{=10.002(2)}\text{A}\text{?}\text{,}\text{Z}\text{=4,}\text{T}\text{=258 K}$), and the monoclinic phase to have another unit cell ($\text{a}\text{=9.951(2)}\text{A}\text{?}\text{,}\text{b}\text{=9.948(2)}\text{A}\text{?}\text{,}\text{c}\text{=10.005(2)}\text{A}\text{?}\text{, β=90.099°,}\text{Z}\text{=4,}\text{T}\text{=250 K}$). In a small temperature range between the cubic and the orthorhombic phase reflexion splittings and the occurence of superstructure reflexions indicate a further intermediate phase.     

Excitation functions of <Superscript>6</Superscript>Li incomplete fusion reactions with Pt nuclei

Experimentally determined excitation functions of the transfer reactions producing ^194–199Au and ^197m Hg isotopes during the interaction of ⁶Li with Pt nuclei are presented. An analysis of the experimental data as compared to EMPIRE-2.18 model calculations and experimental results on the d + ^natPt and α + ^natPt reactions allow determination of the interaction channels of d- and α-clusters in ⁶Li with the target nucleus. The results from model calculations of the reaction cross sections appear considerably lower than the experimental data. This discrepancy in describing the reactions with weakly bound nuclei is probably associated with the incomplete consideration of various interaction channels in the EMPERE-2.18 software. It is clear that a complete understanding of the interaction pattern in these processes requires consideration of the direct channels of ⁶Li nucleus cluster transfer during ⁶Li breakup near the Coulomb barrier.     

Viscoelastic properties of a silicone resin during crosslinking

Viscoelastic properties of a silicone resin crosslinked at various extents were characterised by means of rheology. The influence of temperature on the viscoelastic properties of the material as-delivered and in a state pre-crosslinked approximately to the gel point has been investigated by dynamic-mechanical measurements. While the glass transition temperature is increased by the crosslinking, no changes of the free volume fraction at T _g and its thermal expansion coefficient were observed. Taking the different glass transition temperatures into account, it could be shown that the corresponding WLF-parameters are the same. The molar mass and, hence, the viscosity of the material can be increased by a heat treatment. The dependence of the zero shear-rate viscosity on the weight average molar mass indicates that the existence of entanglements of the polymer molecules is not very probable.