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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 712-715 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An experimental system is described with which exothermic solid-state phase transformations can be made to occur isothermally and their kinetics studied in times as short as 1 s. The system has been applied to the study of the crystallization rate of metallic glasses heated to temperatures well above their glass formation temperatures. Strips of the metallic glass 0.2 cm wide and 5 cm long are resistively heated over a portion of their length to the reaction temperature. They are heated within a 0.3-cm-i.d. tube through which flows a cooling gas. The gas flow rate and electrical current are controlled so as to maintain the sample at constant temperature during the reaction. The rate of reaction is measured by monitoring the intensity of diffraction peaks from the small crystallites which form within the ribbon. The x-ray flux from a bending magnet beam line at the Stanford Synchrotron Radiation Laboratory (SSRL) provides sufficient diffracted intensity to monitor the full development of the crystalline diffraction peaks in times as short as 1 s.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 25 (1969), S. 319-329 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The first order thermal diffuse scattering contribution to integrated Bragg scattering intensities for monatomic, crystalline lattices has been analytically evaluated. Parallel arguments for evaluation of the integrated Bragg intensity and the integrated thermal diffuse scattering intensity are developed for a general diffractometer intensity scan. The resulting general expressions are reduced to a simplified form for several situations. In particular, the two standard integrated intensity scans, an ω-scan and an ω/2θ-scan, are considered. Comparison is made between the results of this calculation and previously published calculations, as well as with recently published experimental measurements of thermal diffuse scattering effects. The variation of the thermal diffuse scattering contributions to the measured intensity is discussed through consideration of a dimensionless parameter, which is independent of both temperature and the diffracting material. This parameter depends only on the experimental constants relating to the intensity measurement and is examined as a function of the detection window size, the scan width and type, and the diffraction angle. It is found, for the situations considered, that the ratio of the thermal diffuse scattering to the Bragg scattering tends to show a pronounced maximum in the intermediate-high angle region (60 ° ≲ 0 ≲ 80 °).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 30 (1974), S. 39-43 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The mean-square atomic displacements and associated Debye temperature of Mg2Sn have been determined from a least-squares analysis of 115 single-crystal X-ray scattering measurements. The mean-square displacements of Mg and Sn are 0.0138 (3) and 0.0097 (1) Å respectively, and the corresponding Debye temperature is 270 ± 3 °K. The data have been analyzed in terms of possible anharmonic contributions to the thermal motion of the Mg atom. An analysis of published specific-heat data was performed to obtain the minus-second moment of the frequency spectrum. The Debye temperature associated with this moment, 281 ± 9°K, is compared with the aforementioned X-ray value.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 32 (1976), S. 467-472 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A new method is reported for evaluating the temperature dependence of Debye-Waller factors, or equivalently the mean-square atomic displacements (MSD), from X-ray spectroscopic data. By irradiating a properly oriented single crystal with polychromatic radiation, several orders of a given Bragg reflection can be simultaneously excited at a fixed scattering angle. These multi-order peaks can then be recorded in a single measurement with an energy dispersive detector. For experiments requiring only relative intensity data, this method offers a number of improvements over conventional techniques, e.g., (i) a substantial reduction in data acquisition time, (ii) a possible reduction in angular flexibility requirements and (iii) access to regions of reciprocal space which might otherwise be inaccessible. This procedure has been employed to determine the temperature dependence of the mean-square displacements of NbC0.98 over the temperature range from 296 to 600 K. These results are compared with published values computed from a double-shell lattice-dynamical force model; the agreement is found to be satisfactory. The data have also been used to evaluate the thermal expansivity of NbC0.98 over the temperature range of measurement; excellent agreement is found upon comparison with published thermal expansion data.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 39 (1983), S. 270-271 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 21 (1966), S. 635-638 
    ISSN: 0001-5520
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 37 (1981), S. 445-446 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 27 (1971), S. 484-487 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The moments of the Au frequency spectrum have been calculated in the usual manner from available thermodynamic data. These results are expressed in terms of the effective Debye temperatures, ΘD(n). Unlike many materials, the values of ΘD(n) for Au increase monotonically with increasing n. Values of the characteristic temperature associated with the Debye–Waller factor are determined [ΘM(0, V0) = 171 ± 2°K and ΘM(300, V300) = 163 ± 1°K], and the temperature dependence of ΘM(T, VT) is estimated. Our results are compared with recent Mössbauer and X-ray data. The comparison with the Mössbauer measurements, which were performed at 4.2 ≤ T ≤ 100°K., yields a value of ̃4.4 for the internal conversion coefficient, α, for the 77 keV, γ-ray line of Au197, this agrees well with a recent independent determination of α = 4.23 ± 0.09. However, our results for ΘM(T, VT) disagree, to within quoted estimates of error, with the results of published X-ray measurements. It is suggested that additional X-ray experiments extending to low temperatures would help to resolve these discrepancies.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 2655-2657 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new method is presented of depositing zirconia-scandia films following evaporation of the oxide powders using an electron beam. The relative amount of Sc was increased in steps from 0 to 8 at. %. In the "as-deposited'' state, all films were amorphous, but crystallized following post-deposition heat treatments. As the atomic percent of Sc was increased, the tetragonal phase of zirconia was stabilized. It appeared as a single phase for compositions with more than 5 at. % Sc.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 992-997 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Substantial improvements have been made in the sensitivity of an ac susceptibility measurement system which determines the pressure dependence of the superconducting transition temperature, Tc(P). The pressure, P, is determined near Tc from the position of the R1 and R2 fluorescence peaks from ruby chips. The system was used to determine Tc(P) for several high Tc single crystals, but was not sufficiently sensitive to determine Tc(P) of polycrystalline samples for HgBa2CuO4+δ. This motivated us to improve the sensitivity of our system. Other parts of the system and the data analysis procedures also have been improved. As a demonstration, Tc(P) of HgBa2CuO4+δ polycrystal to 4 GPa is presented. The improvement of the system using the diamond anvil cell opens the possibility of measuring Tc above 10 GPa and on smaller samples.
    Type of Medium: Electronic Resource
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