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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Fluorine Chemistry 29 (1985), S. 196 
    ISSN: 0022-1139
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0022-1139
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Synthesis principles have been developed for the preparation of solution derived precursors that can be selectively converted to desired refractory materials, as powders, fibres or thick films. The precursors are prepared from aqueous or ethylene glycol solutions containing a pyrolysable organic compound (carbonaceous gel or saccharose) and a soluble molybdenum or tungsten compound (peroxo acid or ethylene glycolate). The concentrated solutions exhibit rheological properties that allow fibre drawing and production of thick films. The sequence of the high temperature reactions – pyrolysis, reduction, carburization – was investigated by thermal gravimetric analysis (TGA), X-ray analysis and nitrogen adsorption. Because of the high homogeneity of the reactants, carbon and transition metal suboxides in the pyrolysed precursors, the observed carburization temperatures (800–1200 °C) are lower than those used industrially. Most of the intermediate and final products–carbon/oxide composites, Mo(C, O), Mo2C, W2C, and WC – are materials of a high Brunauer–Emmett–Teller (BET) surface area (50–200 m2 g−1).
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Polymeric precursors for carbothermal reactions were prepared from niobium alkoxide, tantalum alkoxide and molybdenum ethylene glycolate, respectively, by simultaneous reaction with a chelating reagent (acetylacetone) and organic compounds having two or more reactive OH groups, such as ethylene glycol, saccharose, tartaric acid or dihydroxybenzenes. The precursors exist in common polar and non-polar solvents mostly as linear polymers. The viscous solutions show rheological properties that allow for the preparation of polymer fibres and films. At temperatures up to 1500 °C, bulk precursors as well as fibres and films were thermally converted into carbide powders, fibres and coatings. The structural transformations of the polymeric materials into carbides were investigated using simultaneous thermogravimetric–differential thermal analyses (TGA–DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM).
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Polymeric precursors for carbothermal reactions were prepared from the chelate derivatives of titanium and zirconium alkoxides L2M(OR)2 (L is an acetylacetonato or ethyl acetoacetato group) in alcohols by reaction with organic compounds having two or more reactive OH groups, such as ethylene glycol, saccharose, tartaric acid or dihydroxybenzenes. These organic groups act as bridging ligands in transesterification and condensation polymerization yielding either spinnable viscous solutions or elastic gels. The rheological properties of the concentrated solutions allowed for the preparation of polymer fibres and films. At temperatures up to 1600 °C, bulk precursors as well as fibres and films were thermally converted into carbide powders, films or coatings. The structural transformations of the polymeric materials into the carbides were investigated using thermogravimetric–differential thermal analyses (TGA–DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infra-red (FTIR) analysis and Raman spectroscopy.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The polymeric fluorocompounds Me4[Sn2F10O], Me2SnF4O, Me2SnF2O2, and Me4[Ge2F10O] with Me = Na, K have been prepared by thermal condensation reactions of fluorohydroxostannates and pentafluoromonohydroxogermanates, respectively. NH4 fluorohydroxostannates react at lower temperatures similarly like the corresponding alkali salts, at higher temperatures coloured N-containing tin oxidefluorides are formed.
    Notes: Es werden die Kondensationsreaktionen der Fluorohydroxostannate und von Pentafluoromonohydroxogermanat beschrieben. Reaktionsprodukte sind K4[Sn2F10O], K2SnF4O, K2SnF2O2, K4[Ge2F10O] oder auch entsprechende Natriumsalze. Die nicht mit eckigen Klammern formulierten Salze sind als hochpolymere Gebilde aufzufassen. Ammoniumfluorohydroxostannate zeigen bei niederen Temperaturen ähnliches Verhalten wie die Alkalisalze. Bei höheren Temperaturen entstehen gefärbte stickstoffhaltige Zinnoxidfluoride.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 380 (1971), S. 56-64 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystals of PCl5NbCl5 and PCl5TaCl5 are isomorphous; space group P1. The structures are ionic, consisting of tetrahedral cations PCl4+ and octahedral anions NbCl6- and TaCl6-, respectively. Twinning is frequently observed in both compounds; an explanation thereof is given on the basis of the OD theorie.
    Notes: Die Röntgenstrukturanalyse der kristallisierten Verbindungen PCl5NbCl5 und PCl5TaCl5 ergab: beide Verbindungen sind isomorph und kristallisieren in der Raumgruppe P1. Die Verbindungen sind heteropolar aufgebaut und bestehen aus PCl4+-Kationen und den Anionen NbCl6- bzw. TaCl6-. Der Charakter ihrer Verzwillingung wird diskutiert.
    Additional Material: 6 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 389 (1972), S. 254-262 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: SbCl2F3 crystallizes in the monoclinic space group P 21/n (lattice parameters see above). The crystal structure has been determined by PATTERSON methods and refined three-dimensionally by the method of least squares. The structure is ionic and consists of tetrahedral SbCl4+ cations and anions. In these anions pair of octahedrally coordinated Sb-atoms are linked by a fluorine bridge. A new interpretation of the IR and RAMAN spectra and a discussion of the character of the bonds of the fluorine atoms are given.
    Notes: SbCl2F3 kristallisiert in der monokimen Raumgruppe P 21/n mit a = 11,7; b = 10,4; c = 13,2 Å, β = 94,2° und Z = 12. Die Kristallstruktur wurde mittel PATTERSON- und Elektronendichtefunktionen bestimmt und mit Least -Squares -Methoden dreidimensional verfeinert. Die Struktur besitzt Ionencharakter und besteht aus tetraedrischen SbCl4+-Kationen und den Anionen . In den Anionen sind zwei oktaedrisch koordinierte Sb-Atome über ein Fluorbrückenatom verbunden. Eine neu Interpretation des IR- und RAMAN-Spektrums und eine Diskussion des Bindungscharakters der Fluoratome werden vorgeschlagen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 346 (1966), S. 272-278 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The crystal structure of TaCl4F (tetragonal; a = 12.71, c = 7,84 Å, Z = 8) consists of tetrameric units formed by TaCl4F2 octahedra which are linked via fluorine bridges to a slightly puckered, four-membered ring.
    Notes: TaCl4F kristallisiert tetragonal mit a = 12,71 ± 0,08 Å und c = 7,84 ± 0,05 Å. Die dreidimensionale Strukturermittlung, die mit den aus WEISSENBERG-Aufnahmen erhaltenen h k l-Reflexen (1 = 0 bis 5) durchgeführt wurde, ergab, daß TaCl4F im kristallisierten Zustand tetramere Baueinheiten enthält, in denen TaCl4F2-Oktaeder über Fluorbrücken zu einem schwach gewellten Vierring verbunden sind.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 380 (1971), S. 45-50 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The X-ray analysis of AsCl2F3 is described. Crystals of this compound are isomorphous with PCl5 (space group \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm P}\frac{{\rm 4}}{{\rm n}} $\end{document} a = 8.75, c = 6.23 Å). The atomic parameters were refined by the method of least squares. The compound is heteropolar and consists of tetrahedral cations AsCl4+ and octahedral anions AsF6-.
    Notes: Die Röntgenstrukturanalyse der kristallsierten Verbindung AsCl2F3 wird beschrieben. Die Verbindung ist isomorph mit dem festen PCl5; Raumgruppe \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm P}\frac{{\rm 4}}{{\rm n}} $\end{document} a = 8,75 und c = 6,23 Å. Mit Least-Squares-Methoden wurden abschließend die Atom-parameter verfeinert. Die Verbindung ist heteropolar und besteht aus tetraedrischen Kationen AsCl4+ und oktaedrischen Anionen AsF6-.
    Additional Material: 2 Ill.
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