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
    Hyperfine interactions 62 (1991), S. 353-358 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In connection with a general study of the evolution of tin-oxygen thin films, we report here on the hyperfine interactions of181Ta substitutionally replacting tin in the isolated phases SnO and SnO2. For this purpose, pure SnO pressed powder and a thin SnO2 film were implanted with181Hf. In both cases, unique quadrupole frequencies were found after thermal annealing treatments. The results indicate that the following hyperfine parameters: υ Q = 740.6(2.1) MHz, η=0.07(2) and υ Q = 971.5(1.9) MHz, η=0.72(1) characterize181Ta in SnO and SnO2, respectively.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Влияние дегидрирования поверхности на текстурные свойства, кристалличность и структуру систем AlPO4−ZrO2 (весовое соотношение AlPO4/ZrO2=3), высажденных окисью этилена, исследовали адсорбцией N2 и рентгено-дифракционными измерениями. Увеличение температуры обжига от 773 до 1273 К уменьшает текстурные параметры, что является следствием кристаллизации AlPO4 в тридимитную форму.
    Notes: Abstract The effects of surface dehydration on textural properties, crystallinity and the structure of AlPO4−ZrO2 (weight ratio AlPO4/ZrO2=3) systems precipitated with ethylene oxide have been studied by N2 adsorption and XRD measurements. The increase in calcination temperature in the range 773–1273 K decreases the textural parameters as a consequence of AlPO4 crystallization to the tridymite form.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Использование в качестве катализаторов систем AlPO4−ZrO2 (весовое соотношение AlPO4/ZrO2=3), полученных в окиси этилена и подверженных различной термической обработке, было тестировано в скелетальной изомеризации циклогексена до 1- и 3-метилциклопентенов (1- и 3-МЦП). Кажущиеся константы скоростей и селективности к 1-МЦП использованы для определения наличия и количества кислых центров, единственно способных ускорять скелетальную изомеризацию. Уменьшение каталитической активности с повышением обжига согласуется не только с уменьшением количества кислых центров, измеряемых по сравнению с более слабыми органическими основаниями, но также и с уменьшением кислотности по Брёнстэду, как об этом свидетельствует уменьшение интенсивности полосы O−H.
    Notes: Abstract The use of AlPO4−ZrO2 (weight ratio AlPO4/ZrO2=3) as catalyst systems obtained with ethylene oxide and subjected to different stages of heat treatments has been studied through their catalytic activity in the skeletal isomerization of cyclohexene to 1- and 3-methylcyclopentenes (1- and 3MCP). The apparent rate constants and selectivity to 1-MCP are used for an evaluation of the presence and amount of strong acid sites, the only ones capable of giving rise to skeletal isomerization. The decrease in catalytic activity as calcination increases is consistent with not only the decrease in the amount of acid sites measured vs. weaker organic bases but also with the decrease in Brönsted acidity, as shown by the decrease in O−H band intensity.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Поверхностную кислотность и основность систем AlPO4−ZrO2 (весовое соотношение AlPO4/ZrO2=3), полученных на окиси этилена и подверженных различной термической обработке, исследовали с помощью необратимой адсорбции органических оснований и бензойной кислоты. Уменьшение числа кислотных центров с повышением обжига согласуется с уменьшением кислотности Брёнстэда, как это видно из уменьшения интенсивности полосы O−H. ИК спектры имеют симметрию Td, в которой атом фосфора окружен атомами кислорода в тетраздрической конфигурации.
    Notes: Abstract The surface acidity and basicity of AlPO4-ZrO2 (weight ratio AlPO4/ZrO2=3) systems obtained with ethylene oxide and subjected to different stages of heat treatment has been studied through the irreversible adsorption of organic bases and benzoic acid. The decrease in the amount of acid sites as calcination increases is consistent with the decrease in Brönsted acidity, as shown by the decrease in O−H band intensity. Infrared spectra show Td symmetry in which the phosphorus atom is surrounded by the tetrahedra of oxygen atoms.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 67 (1991), S. 657-660 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Thermal evaporated thin Sn−O films subjected to annealing treatments in air in the range 473–1173 K and in Ar in the range 473–773 K followed by annealings in air up to 1373 K were studied by CEMS (Conversion Electron Mössbauer Spectroscopy). Complementary Mössbauer and X-ray measurements were also performed on SnO powder that underwent the same series of annealings. The presence of the intermediate oxide Sn3O4 was detected. A temptative hyperfine characterization for the Sn2+ site in Sn3O4 is given.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 83 (1994), S. 415-418 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The lattice-dynamical properties of the intermediate oxide of tin (IO) have been investigated over the temperature range 80–295 K. The logarithm of the recoil-free fraction varied linearly with temperature. However, a Debye model does not give a good account of this dependence. By comparison with the other oxides of the Sn-O system, the recoil-free fraction for tin atoms with 2+ and 4+ oxidation states of the IO were estimated. At room temperature, they are 0.463 and 0.323 for 4+ and 2+ states respectively.
    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...