Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 31 (1996), S. 5309-5312 
    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 Well-formed rod crystals of NiWO4 were grown from a Na2W2O7 flux by a slow cooling method. The solubility of NiWO4 in Na2W2O7 increased with increasing temperature. At 1100 °C, NiWO4 was dissolved in Na2W2O7 at a concentration of about 45 mol %. The eutectic temperature was 615± 5 °C. Flux growth was conducted by heating mixtures at 1100 °C for 10 h, followed by cooling to 500 °C at a rate of 5 °C h−1. The brownish and transparent crystals up to 15 mm in length were grown from the mixtures of about 40 g. The most suitable solute content was 30 mol %. The grown crystals were bounded by the {100}, {010}, {110}, {102}, and {111} faces. In certain instances, the {111} faces disappeared. The EPMA data showed that sodium from the flux used was not contained within the grown crystals. The crystals of NiWO4 had a d.c. electrical resistivity of about 1 × 1011 Ω cm.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 33 (1998), S. 653-657 
    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 Reduction of interlayer Co2+ ions in expandable fluorine mica has been attempted. The polyol process using diethylene glycol as a reducing agent was employed. The co2+ -exchanged mica was refluxed at about 225–235 °C in liquid diethylene glycol for 10–120 minutes. Consequently, zero-valence Co metal (Co0) intercalated mica having a metallic grey colour was obtained by in situ reduction of interlayer Co2+ ions, showing different properties from Co2+ -exchanged mica as a precursor. The layer charge of Co-metal-intercalated mica is compensated by protons which are produced through the course of reduction of interlayer Co2+ ions. The reduced sample heated at 350 °C, which had no organic molecules, exhibited a basal spacing of 1.28 nm, indicating the presence of 0.34 nm cobalt metal clusters after subtracting the thickness of the host silicate layer. During the process of reduction in diethylene glycol, cobalt metal particles were expelled from the interlayers which grew to about 0.5 μm onto the external surfaces of host mica crystals with increasing refluxing time.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reactions of diazomethane with butanol, allyl alcohol and β- and γ-halo alcohols led to efficient methylation (giving the corresponding methyl ethers) with the use of a proton-exchanged X-type zeolite compared with H2SO4. The reactions with propylene and isobutylene glycols using the zeolite provided regioselective methylation of the primary OH rather than the secondary or tertiary OH, whereas regioselectivity was not observed in the reactions using H2SO4. The reactions with 2-aminoethanol and 2-mercaptoethanol showed high chemoselective S-methylation and N-monomethylation, respectively, in the presence of the zeolite instead of H2SO4. The mechanism for the reactions is proposed to involve acid-base bifunctional catalysis of the zeolite in which the acidic site reacts with diazomethane to form its conjugate acid, and the nucleophilicity of OH and SH groups is enhanced by the interaction of the basic site with the proton of the groups.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...