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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3063-3066 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the thermal conductivity of two diamond films grown by a chemical vapor deposition process. At room temperature the thermal conductivity is of the order of 10 W cm−1 K−1, i.e., as high as naturally occurring (type Ia) single-crystal diamonds. This value exceeds the thermal conductivity of copper at room temperature by a factor of 2. Since these films consist of microcrystallites of diamonds of dimensions on the order of 2 μm, boundary scattering of phonons is expected to be large. The expected effect of boundary scattering on the lattice thermal conductivity is calculated, and is in qualitative agreement with the observed results above about 30 K. However, important differences between the measured conductivity and that expected for boundary scattering are observed below this temperature. It is proposed that a small amount of disorder present in the lattice (identified through Raman studies) can account for this unusual behavior.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Materials Research 29 (1999), S. 89-116 
    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
    Notes: Abstract Recently there has been a resurgence of research efforts related to the investigation of new and novel materials for small-scale thermoelectric refrigeration and power generation applications. These materials need to couple and optimize a variety of properties in order to exhibit the necessary figure of merit, i.e. the numerical expression that is commonly used to compare one potential thermoelectric material with another. The figure of merit is related to the coefficient of performance or efficiency of a particular device made from a material. The best thermoelectric material should possess thermal properties similar to that of a glass and electrical properties similar to that of a perfect single-crystal material, i.e. a poor thermal conductor and a good electrical conductor. Skutterudites are materials that appear to have the potential to fulfill such criteria. These materials exhibit many types of interesting properties. For example, skutterudites are members of a family of compounds we call open structure or cage-like, materials. When atoms are placed into the interstitial voids or cages of these materials, the lattice thermal conductivity can be substantially reduced compared with that of unfilled skutterudites. These compounds exhibit electrical properties ranging from that of low-temperature superconductors to narrow gap semiconductors.
    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 79 (1996), S. 4002-4008 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polycrystalline samples of Ir4LaGe3Sb9, Ir4NdGe3Sb9, and Ir4SmGe3Sb9 have been made by hot isostatic pressing of powders. The lattice thermal conductivity of these filled skutterudites is markedly smaller than that of IrSb3; thus, void filling shows promise as a method for improving the thermoelectric properties of these materials. We present the lattice thermal conductivity of these filled skutterudites in an effort to quantify the impact of void filling in this structure. It is believed that the atoms "rattle'' in the voids of the structure and therefore interact with a broad spectrum of lattice phonons, reducing their mean free paths substantially below that in the "unfilled'' skutterudites. An additional phonon scattering mechanism is caused by phonon-stimulated transitions between the low-lying energy levels of the 4f electron configurations in the case of Nd3+ and Sm3+. Magnetic susceptibility and Hall-effect measurements are also presented. © 1996 American Institute of Physics.
    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 74 (1993), S. 1793-1798 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results of Shubnikov–de Haas (SdH), cyclotron resonance (CR), and Hall-effect measurements on δ-doped InSb:Si films grown by molecular-beam epitaxy on insulating InP substrates are reported. The investigation covers samples with sheet densities of Si dopant atoms ranging from 1×1011 to 1×1013 cm−2, temperatures from 4.2 to 300 K, and fields from 0 to 7 T. The SdH oscillations show that the samples contain electrons of two-dimensional nature, occupying multiple subbands. The effective masses obtained from the CR data correspond well to the subband occupation densities. The Hall measurements as well as the CR experiments also give evidence for the presence of additional electrons, with the conduction-band-edge mass m*=0.014m0 of bulk InSb, which exist presumably in the bulk of the films.
    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 63 (1988), S. 573-574 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the thermal conductivity κ of a single crystal of barium fluoride from room temperature down to 20 K. This material is used as a substrate for growth of PbTe and other semiconductor materials with applications as electronic devices. The room temperature value of κ is 0.07 W cm−1 K−1, and the thermal conductivity increases as temperature is lowered. At 20 K, the onset of a peak is observed, with a maximum value of approximately 13 W cm−1 K−1. The results are compared with existing data in the literature, and a fit to the data assuming Umklapp scattering of phonons is performed.
    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 69 (1991), S. 846-849 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have synthesized zirconium nitride/aluminum nitride multilayered thin films with a reactive sputtering technique. The electrical transport and optical properties of these multilayers have been examined by resistivity, Hall effect, and near-normal incidence reflectance and transmittance measurements. We show the existence of a metal-to-insulator transition and strong increase of Hall coefficient at small wavelength of composition modulation. The optical response of the multilayers is systematically modified from the behavior of the individual constituents. The measured optical response is in qualitative agreement with a simple effective-medium theory.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 1085-1087 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of grain boundary scattering of lattice waves in high quality diamond films has been determined by the measurement of thermal conductivity down to 0.15 K. We find that the mean free path for lattice vibrations (phonons) exceeds substantially the crystallite size and approaches the physical size of the sample. This implies that a significant transmission of phonons occurs between the grains of these polycrystalline diamond materials.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 291-293 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe the use of accumulation layers of electron charge in applications as magnetoresistive devices. We consider two such systems: an InGaAs/InP heterostructure in which we identify a two-dimensional electron gas from the observation of the quantum Hall effect, and InAs films, in which a strong surface accumulation of charge is inferred from depth profiling studies of the galvanomagnetic coefficients. Magnetoresistive devices fabricated from these materials exhibit outstanding field sensitivity and temperature stability due to the existence of electrons of relatively high density and mobility in the accumulation regions. We also model the magnetosensitivity of our devices.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Thin Solid Films 34 (1976), S. 205-209 
    ISSN: 0040-6090
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Thin Solid Films 28 (1975), S. 357-368 
    ISSN: 0040-6090
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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