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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advances in science and technology Vol. 45 (Oct. 2006), p. 863-868 
    ISSN: 1662-0356
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Natural Sciences in General , Technology
    Notes: We have successfully prepared dense (Sr,Ba)2Nb2O7 ceramics consisting of finemicrostructures by the combination of using double metal alkoxide as the precursor for synthesis ofstrontium barium niobates and applying the spark-plasma-sintering processes. Phase-pureorthorhombic (Sr1-xBax)2Nb2O7 was obtained in the range of 0.8 〈 x 〈 1. The measured permittivityshowed higher values compared with those of the conventionally sintered ceramics, due probably toits higher density and fine microstructures
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 462-465 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spark plasma sintering (SPS) was applied for preparing dense Ca2.75Gd0.25Co4O9 ceramics, and their thermoelectric properties were investigated from room temperature to 700 °C in air. The SPS process was effective in obtaining dense Ca2.75Gd0.25Co4O9 ceramics, typically 98% of the theoretical x-ray density, with lower resistivity, without any degradation of the thermoelectric power. The power factor and figure of merit of the spark plasma sintered samples attain 4.8×10−4 W m−1 K−2 and ZT=0.23 at 700 °C, respectively. © 2001 American Institute of Physics.
    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 70 (1991), S. 5653-5660 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Semiconductive thin organic polymer films have been prepared by the plasma polymerization of 1-benzothiophene. Characteristics of the polymeric products such as their electrical conductivities, optical properties, and electron spin properties have been examined in detail. Doping of these films with iodine has resulted in an increase in electrical conductivity by eight to nine orders of magnitude. The molecular structure of the products has also been discussed.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is demonstrated that a ZnRh2O4 normal spinel with a band gap of ∼2.1 eV is a unique material as a p type wide-gap semiconductor. The electrical conductivity of the sputtered film was 0.7 S cm−1 at 300 K with no intentional doping. The electronic structure was investigated by photoemission and inverse photoemission measurements and indicated that the band gap is composed mainly of ligand field splitting of an octahedrally coordinated Rh3+ octahedron between fully occupied t2g6 and empty eg0 sets. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 3627-3629 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An oxide thermoelectric device was fabricated using Gd-doped Ca3Co4O9 p-type legs and La-doped CaMnO3 n-type legs on a fin. The power factors of p legs and n legs were 4.8×10−4 Wm−1 K−2 and 2.2×10−4 Wm−1 K−2 at 700 °C in air, respectively. With eight p–n couples the device generated an output power of 63.5 mW under the thermal condition of hot side temperature Th=773 °C and a temperature difference ΔT=390 °C. This device proved to be operable for more than two weeks in air showing high durability. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 83 (2000), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dense PbTiO3 ceramics consisting of submicrometer-sized grains were prepared using the spark-plasma-sintering (SPS) method. Hydrothermally prepared PbTiO3 (0.1 μm) was used as a starting powder. The powder was densified to ≳98% of the theoretical X-ray density by the SPS process. The average grain size of the spark-plasma-sintered ceramics (SPS ceramics) was ≲1 μm, even after sintering at 900°–1100°C, because of the short sintering period (1–3 min). The measured permittivity of the SPS ceramics showed almost no frequency dependence over the range 101–106 Hz, mainly because pores were absent from the ceramics. The coercive field of the SPS ceramics was somewhat higher than that of conventionally sintered ceramics, which could be attributed to the small-grained microstructures of the SPS ceramics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dense BaTiO3 ceramics consisting of submicrometer grains were prepared using the spark plasma sintering (SPS) method. Hydrothermally prepared BaTiO3 (0.1 and 0.5 µm) was used as starting powders. The powders were densified to more than similar/congruent95% of the theoretical X-ray density by the SPS process. The average grain size of the SPS pellets was less than similar/congruent1 µm, even by sintering at 1000-1200°C, because of the short sintering period (5 min). Cubic-phase BaTiO3 coexisted with tetragonal BaTiO3 at room temperature in the SPS pellets, even when well-defined tetragonal-phase BaTiO3 powder was sintered at 1100° and 1200°C and annealed at 1000°C, signifying that the SPS process is effective for stabilizing metastable cubic phase. The measured permittivity was similar/congruent7000 at 1 kHz at room temperature for samples sintered at 1100°C and showed almost no dependence on frequency within similar/congruent100-106 Hz; the permittivity at 1 MHz was 95% of that at 1 kHz.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: PbTiO3 sputtering targets 8 cm in diameter were prepared using spark-plasma sintering (SPS) for relatively short periods, ∼2 min. Submicrometer-sized PbTiO3 powders with a relatively large size distribution were densified to ∼86% of the theoretical X-ray density using the SPS process. In contrast, large-sized (8 cm in diameter) ceramics could not be prepared from starting powders with a relatively narrow particle-size distribution. Formation of cracks in the large PbTiO3 targets was observed when samples were prepared under higher pressures (〉50 MPa) or at higher temperatures (〉900°C). Crack formation was attributed to unrelaxed internal stress originating from lower pore contents and from an inhomogeneous distribution of cations in the ceramics prepared under these conditions.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Spark-plasma-sintering (SPS) has been applied to BaTiO3 to prepare dense ceramics consisting of submicrometre-sized powder. Relatively dense (typically 97% of the theoretical X-ray density) pellets with an average grain size remaining similar to that of the starting powder, approximately 0.6 μm, were obtained by the SPS process. Fixed frequency (1 kHz) measurements show the room temperature permittivity of SPS ceramics to be relatively high, approximately 3500, and at least double the value of conventionally sintered ceramics, approximately 1500. Alternating current (a.c.) impedance spectroscopy measurements show that SPS is an effective process to reduce the influence of intergranular (grain boundary) effects on the permittivity and direct current (d.c.) resistance characteristics of BaTiO3 ceramics substantially.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 315-322 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have studied in more detail aspects of the soliton-antisoliton pair in a trans-polyacetylene chain based on our previous study of the midgap levels associated with the photogenerated oppositely charged soliton-antisoliton pair in conductive polymers employing the concept of the molecular orbital interaction (Part I of this study, this issue). The intersoliton distance has been estimated to be about 10 Å from the Pariser-Parr-Pople method. We have found that the energy gap between the midgap levels is estimated to be 0.45 eV, being significantly related to an additional photoinduced absorption.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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