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  • 1990-1994  (8)
  • 1970-1974
  • 1994  (8)
Materialart
Erscheinungszeitraum
  • 1990-1994  (8)
  • 1970-1974
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 2435-2441 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Powdered samples of the type Ce1−xRExO2−y, where RE=La, Pr, Nd, Eu, Gd, and Tb, are synthesized over the range 0≤x≤0.5 starting from nitrate solutions of the rare earths. X-ray diffraction and Raman scattering are used to analyze the samples. These compounds, at least in the low doping regime and for strictly trivalent dopants, form solid solutions that maintain the fluorite structure of CeO2 with a change in lattice constant that is approximately proportional to the dopant ionic radius. The single allowed Raman mode, which occurs at 465 cm−1 in pure CeO2, is observed to shift to lower frequency with increasing doping level for all the rare earths. However, after correcting for the Grüneisen shift from the lattice expansion, the frequency shift is actually positive for all the strictly trivalent ions. In addition, the Raman line broadens and becomes asymmetric with a low frequency tail, and a new broad feature appears in the spectrum at ∼570 cm−1. These changes in the Raman spectrum are attributed to O vacancies, which are introduced into the lattice whenever a trivalent RE is substituted for Ce4+. This conclusion is supported by a simple model calculation of the effects of O vacancies on the Raman spectrum. The model uses a Green's function technique with the vacancies treated as point defects with zero mass.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 4046-4054 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: In this work fast-changing bias conditions in the nanosecond regime are applied to n-channel metal-oxide-semiconductor field effect transistors. Short bunches of holes are injected into the silicon dioxide (SiO2) and subjected to different field conditions which influence the final trapping. It is shown that by this experiment the kinetics of hole movement in the oxide can be studied. The model of polaron formation originating from work on high-energy irradiation is essentially confirmed. Evidence for a prepolaron formation phase is found, however, with a smaller scattering length for which we propose the different hole formation process in this experiment to be responsible. On this basis the interface trap formation by injected holes is investigated. It is found that not the number of trapped holes but the one of injected holes is decisive for interface trap formation.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 2171-2173 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: It is demonstrated that SiC films can be deposited epitaxially on [001] and [111] Si wafers by excimer laser ablation of just a carbon target, in vacuum, at deposition temperatures as low as 1100 °C. Diffraction studies show that the SiC films have the same crystalline orientation as the substrates. The film growth on the Si substrate to thicknesses as large as 4000 A(ring) with no significant excess carbon indicates that in addition to reaction of the carbon in the plume with Si of the substrate, there is transport of Si within the SiC film. For continued deposition beyond this thickness a carbon layer will form. © 1994 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 737 (1994), S. 0 
    ISSN: 1749-6632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Macromolecules 27 (1994), S. 279-286 
    ISSN: 1520-5835
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 113 (1994), S. 0 
    ISSN: 1439-0523
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: The interaction between varieties and environment can make the prediction of crop performance difficult. The farmer is obviously interested in achieving optimum production within the particular growing environment of his farm, thus, this paper investigates if crop performance predictions can be improved by making information from other locations into account. The investigation is based on yield data from winter wheat resulting from official German variety-performance tests. The predictors are based on the single location (control), unweighted means, principal components, and weighted means, produced using regression coefficients as weights. These predictors were tested on an independent data set from another year. For the given yield data in winter wheat, the overall mean proved to be the best, which suggests that prediction for all locations should be the same, and predictors for specific locations cannot, therefore, be recommended. The main reason for this is the relatively small interaction between genotype and location, in comparison to the second-order interaction between genotypes, locations and years.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1572-879X
    Schlagwort(e): ellipsometry ; methane ; palladium ; palladium oxide ; oscillations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Ellipsometry is used to follow the growth of a PdO layer on the surface of a thick Pd-film catalyst during methane oxidation at ∼ 500°C. The oxide layer that develops under rich conditions (excess CH4) is quite porous and roughens with time. Little CO is formed during this period, but the CO2 formation rate increases until spontaneous oscillations develop, which correlate with changes in the ellipsometric data. These changes indicate that the porous oxide rapidly converts to a metal-rich state, which has decreased catalytic activity, and then slowly reoxidizes.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 31 (1994), S. 53-54 
    ISSN: 1434-6079
    Schlagwort(e): 34.80.D ; 32.80.H
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract From intensity of Auger transitions (1s2p)−1 1 P,3 P→2p −3 2 P,2 D+e A − relative to 1s −1 2 S→2p −2 1 D+e A − measured at ϑ=54 and 90° relative to the primary electron beam we have determined the alignment of double vacancy states (1s 2p)−1 1 P and3 P of neon for electron impact ionization for the impact energies 1.5, 2.0, 2.5 and 4.0 keV. ForE 0=1.5, 2.0 and 2.5 keV the alignment is compatible with zero with an upper limit of , forE 0=4.0 keV a small negative value was found.
    Materialart: Digitale Medien
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