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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 249-254 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Period expansion after annealing in tungsten/carbon (W/C) multilayer films has been observed by several authors. Although most results have emphasized that the carbon layers play the important role in such thermal evolution, it is important to clarify the structure of the carbon atoms in those multilayers both before and after annealing in order to explain such period expansion more clearly. In this paper, Raman scattering is carried out on the W/C multilayers fabricated by various methods, all of which showed different period expansion values ranging from 0% to 20%. We show that the initial carbon in those multilayers becomes graphitized differently depending on the fabrication methods. The carbon fabricated by rf sputtering under a reactive gas has the highest amount of graphite component as compared with those prepared under a pure argon gas atmosphere. After annealing at 1000 °C, graphitization can be observed, but there are no obvious structural differences for the carbon in all the annealed W/C multilayer films. Such graphitization of the carbon layer causes a decrease in its density, and thus an increase in its thickness. Due to the different initial states of the carbon in the multilayers produced by the different methods and to the identical final state after annealing, the different carbon layer thickness expansions are expected and do agree with the small angle x-ray diffraction measurements.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 931-937 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A series of W/C multilayers has been fabricated using a magnetron sputtering device. In order to establish comparison with other multilayers produced by several laboratories, their atomic structure and thermal evolution has been studied by small- and wide-angle x-ray scattering, respectively, and Raman spectroscopy. By plotting the nominal thickness determined by the sputtering speed versus the thickness obtained by simulation of small-angle x-ray scattering spectra the existence has been confirmed of a WC interface compound of about 0.7 nm formed during the multilayer deposition. The multilayers fabricated by the magnetron sputtering device showed higher thermal stability and less period expansion than those produced by different apparatus [Dupuis et al., J. Appl. Phys. 68, 5146 (1990), Jiang et al., J. Appl. Phys. 65, 196 (1989)]. Raman spectra indicated that the carbon in the W/C multilayers is more graphitized than in the previous W/C multilayer. The carbon is further graphitized after annealing at 1000 °C. The graphitization of carbon induced its density to decrease, that is, thickness to increase. Consequently, in the multilayers a smaller expansion of carbon is expected after annealing at 1000 °C since there is more graphitized carbon in the initial as-deposited state than in the previous W/C multilayer. This conclusion agrees very well with the thickness variation measured by x-ray diffraction.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 3348-3355 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Multilayers consisting of alternating thin bilayers of W and Si (period: 1.5〈d〈9 nm) have been analyzed by x-ray scattering (absolute reflectivity, period, mosaicity, interface roughness, crystallinity, and density) and by cross-sectional transmission electron microscopy observations (periodicity, crystalline phase, and damaged area). Our purpose was to determine the thermal properties of the multilayers with respect to the period value under pulsed laser heating (with a nanosecond Nd-YAG laser at different energy densities up to 1 J/cm2 and at a wavelength λ=0.53 μm) and by furnace annealing (250〈T〈1000 °C under 10−7 Torr pressure). We propose that two distinct diffusion mechanisms are involved in annealings: first, interdiffusion in the amorphous phase and then crystallization into WSi2, the latter related to a period contraction of about 5–10%. The diffusion coefficients and the crystallization temperature depend drastically on the period value. Simulations of small-angle x-ray scattering curves take well into account this thermal evolution. Extinctions and modulations of the intensities of the Bragg peaks are well fitted by thickness and roughness variations.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 5146-5154 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The thermal behavior of X/C multilayers (nanometer-thick layers made of tungsten, nickel, or SiWSi alternating with carbide or pure carbon) was studied. Two types of annealing were performed: the pulsed laser annealing in air and the classical thermal annealing in a vacuum furnace. Depending on the composition and the structure of the layered materials, thermal stability or diffusion mechanisms were observed and further analyzed by small-angle x-ray scattering, transmission electron microscopy, and Auger electron spectroscopy. The results show that the period expansion and the reflectivity evolution, that were observed in some cases after treatment, are caused both by structural changes into the layers and by exchange of matter between layers. These changes always induce a partial graphitization of the amorphous carbon and, in the case of W/C multilayers, the formation of a W2C compound.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 6916-6918 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present positive and negative exchange bias (EB) phenomena observed in two ferrimagnetic-based amorphous bilayers systems: FeSn/FeGd and FeGd/TbFe. In both cases, magnetization measurements exhibit a shift of the loop of one of the ferrimagnetic layer towards a positive or negative field. In FeSn/FeGd, the coupling at the interface between the net magnetization of the two layers is antiferromagnetic, which leads to a positive shift. However in FeGd/TbFe bilayers, the coupling is ferromagnetic and the shift is negative. The EB phenomenon is attributed to the occurrence of a magnetic domain wall present at the interface, which can be "compressed" or "decompressed" by an external applied field. A simple model based on the competition between the Zeeman energy and the interface exchange interaction energy permits a good quantitative evaluation of the observed EB fields. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 5309-5313 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have prepared iron nitride thin films by reactive rf sputtering of an iron target in an argon-nitrogen plasma. The films present a wide variety of structures and compositions: α expanded bcc iron, amorphous Fe1−x-Nx, γ'-Fe4N, ε-Fe2–3N, and ζ-Fe2N. Evolutions of the crystallographic structures and of the magnetic properties of the obtained phases are discussed versus the nitrogen concentration in the gaseous flow and the substrate temperature during deposition. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 1229-1233 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The interdiffusivity and chemical ordering in compositionally modulated (Λ=20 to 40 A(ring)) amorphous Fe70Si30/Si thin films have been measured from the decay of the satellite intensities of the (000) x-ray scattering peak during isothermal anneals in the temperature range 373–473 K. Diffusivities as low as 10−26 to 10−25 m2 s−1 have been measured. A linear dependence of D˜Λ on 1/Λ2 has been observed, providing the evidence of chemical ordering in Fe-Si alloy and leading to the determination of a critical wavelength.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 3554-3554 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the 59Co and 119Sn hyperfine fields in amorphous CoSn alloys obtained by coevaporation onto cryogenic substrates. 59Co spin-echo spectra were measured at 1.4 K in zero-applied field on ferromagnetic Cox Sn1−x (0.65≤x≤0.80) alloys. NMR spectra display peaks. These peaks have a relative intensity which varies with composition, but their average location in frequency is concentration independent. From a comparison with 59Co NMR spectra in crystalline Co with dilute Sn impurities, it is inferred that the structures observed in NMR spectra for amorphous CoSn alloys are related to the number of Sn first neighbors of the Co resonant nuclei. Thus, short-range effects are thought to be predominant in determining the Co on-site moments in these alloys, as well as in amorphous Co alloys with other s-p elements. 119Sn Mössbauer spectra were measured at room temperature on paramagnetic Cox Sn1−x (0.40≤x≤0.55) alloys. Comparison is made with the stoichiometric CoSn crystalline compound, where quadrupolar interactions give rise to an admixture of two doublets corresponding to the two inequivalent Sn sites. Mössbauer spectra for the amorphous CoSn alloys display a single doublet identified as arising from Sn atoms in trigonal prisms arrangements. These results are discussed within the frame of current models for the structure of metallic glasses.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 21 (1988), S. 317-321 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: X-ray diffraction in multilayer structures is determined by the electronic concentration profile, which depends both on the atomic concentration and on the specific volume. Probing with photons of different wavelengths in the vicinity of an absorption edge (anomalous X-ray scattering) produces a variation of the scattered intensity, which allows the separation of both contributions. A test of the feasibility of this method on several multilayer samples is presented. The technique appears to be sensitive enough to measure specific volume ratios with a precision of about 5%.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Physics and Chemistry of Solids 36 (1975), S. 1135-1145 
    ISSN: 0022-3697
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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