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  • 1
    Electronic Resource
    Electronic Resource
    Further evidence for a "second universality'' in alternating-current conductivity relaxation (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4429-4431 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The existence of a regime of constant-loss (independent of frequency) behavior was reported earlier, based on ac conductivity measurements at low temperatures and/or high frequencies, for a wide range of ionically conducting crystalline materials and glasses. Here new results in support of this concept are presented. First, it is shown that the example of NaCl:Zn2+ which Macdonald examined in detail [J. Appl. Phys. 75, 1059 (1994)] is a poor one to serve as a test of constant-loss behavior. Additional cryogenic measurements, and a more detailed analysis of both the real and imaginary parts of the complex dielectric constant for materials such as crystalline CaTiO3:Al3+ and Na2O⋅3SiO2 glass are shown to support the conclusion that constant-loss behavior occurs at low temperatures for a wide range of materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357338
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  • 2
    Electronic Resource
    Electronic Resource
    The Golden Age of Crystal Defects (1996)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Materials Research 26 (1996), S. 1-19 
    Details
    ISSN: 0084-6600
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ms.26.080196.000245
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  • 3
    Electronic Resource
    Electronic Resource
    Dielectric relaxation and deuteron NMR of water in polyimide films (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 5290-5296 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polyimide films containing up to 3.2 wt. % water (H2 O or D2 O) have been studied by dielectric relaxation (DR) and 2H nuclear magnetic resonance (NMR) spectroscopies. Dielectric loss measurements show the presence of a double peak near 200 K due to water, with two components designated as γ1 and γ2 . The γ2 peak, which appears at the lower temperature, is only present for the interior portion of thick (〉25 μm) films and rapidly decreases as the moisture content decreases. Correspondingly, deuteron NMR measurements show the presence of narrow and broad lines, which are correlated, respectively, with the γ1 and γ2 DR peaks. The spin-spin relaxation time T2, is much longer for the narrow line than for the broad line. The γ1 DR peak and the narrow NMR line are attributed to sites where isolated water molecules are only loosely coupled to the polymer chains. The γ2 and broad NMR lines involve small clusters of water molecules with associated nuclear magnetic dipole-dipole coupling. Additional measurements on polyimides containing methanol and acetic acid absorbents are also reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343719
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  • 4
    Electronic Resource
    Electronic Resource
    Protons and other defects in Fe-doped KTaO3 (1992)
    Springer
    Applied physics 55 (1992), S. 324-331 
    Details
    ISSN: 1432-0630
    Keywords: 61.70−r ; 66.10.Ed ; 76.30.Fc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The properties of defects in Fe-doped KTaO3, both in the form of single crystals and polycrystalline ceramics, have been investigated for a wide range of Fe concentrations. The techniques employed included infrared (IR) absorption, electron paramagnetic resonance (EPR), and ac electrical conductivity together with complex-impedance analysis. Samples were pretreated (at 900° C) in water vapor to introduce protons which take the form of OH· O defects, and were also treated at various oxygen partial pressures. A calibration of the OH− IR absorption band was carried out with the aid of a deuterium nuclear-probe method. EPR showed cubic and axial Fe3+ spectra, but only the axial spectrum appeared for crystals with high Fe concentrations. Pre-dominantly proton conductivity was observed for samples treated in reducing atmospheres, and a proton-hopping activation energy of 0.73 eV was deduced. For samples treated in high oxygen pressures, however, hole conduction dominated. Evidence for proton interaction effects was also found, but the nature of the traps is not clear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00324079
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  • 5
    Electronic Resource
    Electronic Resource
    Dielectric relaxation and computer simulation studies of rutile-structured MnF2 crystals (1989)
    Springer
    Applied physics 49 (1989), S. 69-73 
    Details
    ISSN: 1432-0630
    Keywords: 77.40 ; 61.70 ; 66.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The fluorides of the rutile structure are relatively simple ionic materials with tetragonal symmetry for which the dominant intrinsic defect has not been established. The present experiments involve low-temperature dielectric relaxation measurements on Er3+-and Y3+-doped MnF2 single crystals. Unexpectedly, dielectric loss peaks were observed at cryogenic temperatures, involving very low activation energies,E. For both dopants a prominent peak is observed for samples oriented parallel to thec-axis withE ∼ 6 meV and in perpendicular orientations withE=37 meV for Er3+ and 46 meV for Y3+ doping. Such lowE-values are probably too small to be controlled by lattice migration of a defect. Rather, we expect that they are due to a very low symmetry configuration created when the ions near the defect move “off symmetry” to a more stable configuration. Computer simulation calculations have been carried out which are much improved over early studies of this system in terms of the code used and the F-F interatomic potentials. The results show that the energy per defect for the anion Frenkel (1.53 eV) is lower than that of the Schottky (1.99 eV). It was also shown that the fluorine interstitial, Fi, adopts a split-interstitial form. This defect associates strongly with trivalent dopants Er and Y to produce a low symmetry dipolar structure with the necessary off-symmetry configuration to explain the experimental findings. Since there is no alternative way to explain these low temperature relaxations in terms of impurities associated with Mn vacancies, as would be required by the Schottky model, we conclude that these experiments serve to establish the nature of the intrinsic defect in MnF2 as anion Frenkel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615467
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  • 6
    Electronic Resource
    Electronic Resource
    Nature of the constant-loss dielectric response of various crystals and glasses (1993)
    Springer
    Applied physics 56 (1993), S. 8-14 
    Details
    ISSN: 1432-0630
    Keywords: 66.90.+r ; 77.40.+i
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract For a wide range of crystalline materials and glasses, it has been shown that, at low temperatures, the ac conductivity σ(ω) is proportional to frequency ω, corresponding to a loss per cycle that is independent of frequency. This paper explores the features of this constant-loss behavior, showing that it is a truly bulk phenomenon, that it is only slowly dependent on temperature (i.e., not activated) and, in the case of glasses, that it does not give rise to a mixed alkali effect. The “pair approximation” model with hopping over an asymmetric barrier is fitted to some of the results, but doubts remain as to whether this model is appropriate for systems with low defect concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351896
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  • 7
    Electronic Resource
    Electronic Resource
    X-ray diffraction procedures for polycrystalline and amorphous materials. H. P. Klug and L. E. Alexander. John Wiley and Sons, Inc., New York (1954). 716 pages. $15.00 (1956)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 2 (1956), S. 140-140 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690020128
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  • 8
    Electronic Resource
    Electronic Resource
    Electrons, atoms, metals and alloys. William Hume-Rothery. Revised edition. Philosophical Library, New York (1955). 387 pages. $10.00 (1956)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 2 (1956), S. 18J 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690020233
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  • 9
    Electronic Resource
    Electronic Resource
    Sorption of water and organic solutes in polyimide films and its effects on dielectric properties (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 545-555 
    Details
    ISSN: 0887-6266
    Keywords: polyimides ; dielectric relaxation ; dipole moments ; water sorption ; diffusion ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of structure on the sorption kinetics of water and of various organic solutes into polyimide (PMDA-ODA) thin films was studied. The major techniques employed include measurements of sorption kinetics, density, and dielectric relaxation. More solute uptake, lower densities and higher diffusivities were observed for films cured at lower temperatures. By measuring both changes of mass and of density, the volume expansion of the polymer due to each solute was obtained; this was found to be proportional to the molar volume of the solute. The two dielectric relaxation peaks (denoted by γ1 and γ2) due to water (and other solutes) were studied in detail to obtain the relevant activation energies and the separate dipole moments. While water and methylene chloride appear in both γ1 and γ2 configurations, methyl and ethyl alcohol appear mainly as γ2, while acetic acid is primarily γ1. It was concluded that the γ1 configurations are relatively homogeneously distributed throughout the polymer, involving loose bonding to the polymer structure, while the γ2 configurations involve small clusters, probably chains of molecules. © 1993 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090310505
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  • 10
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    Anelastic Measurements of Atomic Mobility in Substitutional Solid Solutions (1952)
    American Physical Society
    Details
    Publication Date: 1952-11-15
    Print ISSN: 0031-899X
    Electronic ISSN: 1536-6065
    Topics: Physics
    Published by American Physical Society
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