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  • Electronic Resource  (79)
  • 1
    Electronic Resource
    Electronic Resource
    Thermal pulse study of the polarization distributions produced in polyvinylidene fluoride by corona poling at constant current (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3357-3365 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A thermal pulse study of the polarization profiles in samples of 12-μm-thick, biaxially oriented polyvinylidene fluoride after corona poling under approximately constant-current conditions, using a modified corona triode in atmospheric air, is reported. An electrical characterization of the corona triode is also reported to show how it may be operated in the constant-current mode. Samples poled without electrode on the corona-exposed surface show polarization distributions sensitive to the corona polarity, with polarization depletion on the corona side of the samples when the corona is positive. Polarization-reversal experiments show switching inhomogeneities with a pronounced dependence on the initial corona polarity. The above observations are consistent with a simple model in which positive charges from the positive corona partially penetrate the sample during poling and cause an inhomogeneous reduction of the poling field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354561
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  • 2
    Electronic Resource
    Electronic Resource
    Thermal stability of internal electric field and polarization distribution in blend of polyvinylidene fluoride and polymethylmethacrylate (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3366-3372 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is confirmed that a melt-quenched and annealed blend of 80 wt % polyvinylidene fluoride and 20 wt % polymethylmethacrylate has the β-crystal form of PVDF with optical clarity and other properties that are desirable for a host material in a guest-host system where the guest is an optically nonlinear dye that is orientationally stabilized by the strong internal electric field of a poled ferroelectric. Combined measurements, in such a blend, of the internal electric field Ei, the pyroelectric coefficient Cpyro, and the polarization distribution after electrically poling and subsequently thermally aging for 2 h intervals at temperatures up to 120 °C are reported. Ei and Cpyro increase with increasing poling field Ep. Ei was found to be as large as three times Ep. An unexpected thermal stability of Ei was observed at annealing temperatures above the glass transition temperature of 60 °C up to 100 °C when significant loss of Cpyro was measured. Thermal pulse results yield polarization distributions that may be attributed in part to dipolar polarization and in part to space charge. The prolonged thermal stability of Ei is ascribed to space charge that does not contribute to Cpyro. The poled blend shows second-harmonic generation with a nonlinear coefficient d33 of around 1 pm/V (9×10−9 esu).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354562
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of the polarization-depth distribution in poled ferroelectric ceramics using thermal and pressure pulse techniques (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 854-863 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This paper is the first of a series with the common theme of comparing thermal and acoustic pulse methods of measuring charge or polarization profiles across the thickness of slab-shaped samples that are representative of different types of materials. In this paper, thermal and pressure pulse measurements are reported of the polarization distribution in poled, ferroelectric ceramic samples. The results obtained from both methods are complementary so that there is a benefit to using both. The results also demonstrate that large deviations from uniform polarization can be induced by processing differences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351306
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  • 4
    Electronic Resource
    Electronic Resource
    Polarization distribution in ceramic-polymer nanocomposites (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 2712-2718 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report pyroelectric responsivity versus depth profiles in nanocomposites of powdered barium titanate and tripropylene glycol diacrylate obtained by using the thermal pulse (TP) method. The ceramic nanopowder (mean particle size 270 nm) was prepared by combined solid-state polymerization and pyrolysis of a metallo-organic precursor. Films of powder/monomer dispersion (thickness ∼30 μm) were cured by irradiation with an electron beam (energy 140 keV, dose 80 kGy). The observation of a TP response after electron beam curing (EBC) indicates the appearance of a poling electric field as an effect of the EBC. The polarization depth profiles were studied for different filler contents. The composites show potential promise for piezo and pyroelectric sensors applications and for charge storage in microelectronics. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371115
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  • 5
    Electronic Resource
    Electronic Resource
    Evidence for a Glycidic-Lipidic Matrix in Human Neuromelanin, Potentially Responsible for the Enhanced Iron Sequestering Ability of Substantia Nigra (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 62 (1994), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The high-resolution solid-state 13C-NMR spectrum of a neuromelanin specimen (from patients dying from nonneurological diseases) is compared with that obtained from enzymatically prepared dopamine-melanin. The main differences between the two spectra suggest the occurrence in neuromelanin of a glycidic/lipidic matrix tightly associated with the melanin macromolecule. Atomic emission spectroscopy revealed high iron content (1.5%) in the neuromelanin specimen, in full agreement with previous reports. These observations support the view that neuromelanin acts as a strong chelating (and insolubilizing) system for iron ions and further suggest that the attack to this compact composite substrate may be an important step to allow the release of iron ions responsible for the increased lipid peroxidation reported in the pathogenesis of Parkinson's disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1994.62010369.x
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  • 6
    Electronic Resource
    Electronic Resource
    Thermal pulse study of the electric polarization in a copolymer of vinylidene cyanide and vinyl acetate (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 6407-6415 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The polarization induced by thermopoling the alternating vinylidene cyanide/vinyl acetate copolymer has been studied by the thermal pulse technique. The mean polarization over the thickness and its spatial profile were determined as functions of the poling variables: electric field, time, and temperature. Additionally, the thermal stability of the polarization was studied between ambient temperature and the glass-transition temperature of 175 °C. The mean polarization was found to be proportional to the poling field up to the maximum field used of 42 MV/m and to be very stable up to 150 °C. The polarization profiles obtained after poling were found to be highly inhomogeneous, especially for short poling times, indicating positive charge injection from the positive electrode during poling. The polarization distribution continues to evolve after the mean polarization has reached a steady state indicating separate time scales for space-charge migration and dipole reorientation. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363639
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  • 7
    Electronic Resource
    Electronic Resource
    Study of poling behavior of biaxially stretched poly(vinylidene fluoride) films using the constant-current corona triode (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 5597-5603 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This article reports systematic results of corona poling measurements obtained on biaxially stretched polyvinylidene fluoride films charged in dry air. Charging was performed using the constant current corona triode. The dependence of the poling process on the sample thickness, charging current, and successive charging processes was investigated. Phase transitions from α to δ and to β phases were observed when virgin samples were corona charged. The thermal pulse technique showed that the polarization profiles during charging can be made consistently almost uniform and that the ferroelectric reorientation can be associated with the rising plateau region displayed on potential buildup curves. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359682
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  • 8
    Electronic Resource
    Electronic Resource
    Pulsed electrothermal technique for measuring the thermal diffusivity of dielectric films on conducting substrates (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 6124-6128 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A simple technique for measuring the thermal diffusivity of dielectric films on thermally sinking substrates is proposed and demonstrated. It is an outgrowth of the thermal pulse technique for measuring charge and polarization profiles. The thermal diffusivity is derived from the transient electrical response induced by a thermal pulse applied to a dc voltage-biased sample. Because the response is proportional to the bias voltage, the signal-to-noise ratio is adjustable independently of the thermal pulse energy and may be made as large as required for determining the diffusivity with high precision. Measuring times of around 1 ms or shorter are sufficient for polymers with thicknesses up to 10 μm. Experimental results for two different polyimide films spin coated on crystalline silicon substrates are presented and discussed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363687
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  • 9
    Electronic Resource
    Electronic Resource
    Deuterium magnetic resonance study of orientation and poling in poly(vinylidene fluoride) and poly(vinylidene fluoride-co-tetrafluoroethylene) (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 541-547 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deuteron nuclear magnetic resonance line shapes are reported for oriented samples of poly(vinylidene fluoride) and an (80–20) copolymer of vinylidene fluoride and tetrafluoroethylene. For stretched samples the orientation of the chain axes with respect to the stretch direction is given by a Gaussian distribution of width ≈20°. The width of the distribution was slightly smaller in the more highly stretched copolymer. Surprisingly, as the magnetic field is rotated in the plane perpendicular to the stretch direction, the deuterium spectra of the poled copolymer sample do not change. The occurrence of electrical polarization in the absence of orientation dependence of the deuterium line shape indicates molecular reorientation through 180° in the copolymer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343137
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  • 10
    Electronic Resource
    Electronic Resource
    NMR Evidence for Interconversion between Two Enantiomeric Forms of Macrocyclic Schiff Base Lanthanide(III) Complexes Through Reversible Ring Contraction and Expansion (1995)
    s.l. : American Chemical Society
    Inorganic chemistry 34 (1995), S. 5825-5831 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic00127a021
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