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  • 1
    Electronic Resource
    Electronic Resource
    Thermal conductivity of thermoelectric Si0.8-Ge0.2 alloys (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 4258-4263 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The thermal conductivity of heavily doped, n-type Si-Ge alloys has been studied from 300 to 1200 K. The scattering rate of several phonon scattering mechanisms has been calculated, including intrinsic scattering, mass defect and distortion scattering, phonon-electron scattering, and scattering by inclusions. These rates were then used to calculate the lattice thermal conductivity. The electronic component of the thermal conductivity was calculated from the calculated Lorenz ratio and measured values of the electrical conductivity. The total thermal conductivity was then compared to measured values for a specimen studied by Vining et al. [J. Appl. Phys. 69, 15 (1991)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350806
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  • 2
    Electronic Resource
    Electronic Resource
    Electrical resistivity of inhomogeneous alloys (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 4322-4325 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The resistivity of an inhomogeneous medium is expanded in Fourier components and the effective resistivity is defined in terms of the rate of entropy production per unit current density. The effective resistivity lies below the volume average by an amount proportional to the mean square fluctuation in resistivity and containing an angular factor, as previously obtained by Herring. The angular factor is obtained in the absence of a preferred direction, and for the case of ellipsoidal symmetry. The effect of the neglect of higher order terms is discussed. The theory is applied to two-phase systems of low contrast and to cases of nonuniform solute concentration. Homogenization increases the resistivity. The time dependence of this increase is discussed in general and for solute clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349111
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  • 3
    Electronic Resource
    Electronic Resource
    Reduction of stored energy in a heavily irradiated ceramic (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 2062-2064 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The decrease of stored energy that accompanies redamage of a metamict ceramic is compared with the calculated elastic strain energy resulting from the volume misfit between the disordered inclusions and the crystalline matrix. In the case of self-damaged CaPuTi2O7 it is found that the elastic energy contributes no more than 20% to the observed energy decrease. The major part of this decrease must be attributed to rearrangement of atoms by the redamage process into configurations of lower energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339550
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  • 4
    Electronic Resource
    Electronic Resource
    Thermal process models for the interpretation of microstructures formed during electron-beam surface melting (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 3953-3959 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An analysis is presented of mechanisms involved in forming rapidly solidified surface layers on a substrate material by an electron beam. This can be achieved either by (i) point-source or by (ii) line-source melting. In mode (i) it is critical that minimal cooling occur between successive beam oscillations so as to avoid solid-state induced transformations where adjacent rapidly solidified zones overlap. In mode (ii) a linear heat source is formed by oscillating the beam sufficiently rapidly and moving this line source transversely over the surface to form a homogeneous rapidly solidified layer. The conditions for this to occur are mathematically predicted. A theoretical model yields the minimum oscillation frequency for this to occur. Under steady-state heat flow conditions the following features were studied: stability of the cavity, geometry of the melt zone, and rate of cooling during solidification. It is shown that a linear vapor cavity exists in mode (ii), provided the oscillation frequency of the beam exceeds a critical value, typically ≈250 Hz. The predicted cavity depth is shown to correspond to the depth of the turbulent flow region, as revealed by microstructural observations. The molten pool length is governed by the steady-state heat conduction requirements, whereas the depth is found to be empirically related to process parameters. Predicted values of the cooling rate are compared with those deduced from the microstructural scale and the solidification morphology for the case of a molybdenum high-speed steel (M7). Theoretical and experimentally obtained values are shown to be in good agreement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339193
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  • 5
    Electronic Resource
    Electronic Resource
    Thermoelastic attenuation of Rayleigh waves (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 2593-2598 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thermoelastic attenuation of Rayleigh waves is larger than that of bulk waves because heat is conducted not only in the propagation direction, but also normal to the surface. This attenuation is further enhanced if the thermal expansivity is a function of depth below the surface. Expressions are obtained for the attenuation and some experimental data on Rayleigh wave attenuation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335888
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  • 6
    Electronic Resource
    Electronic Resource
    Electrothermal breakdown: Solutions for the case of thermal resistance in the electrodes (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 1601-1605 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An exact solution is found for the critical voltage at a thermal instability corresponding to a particular model of a dielectric under high applied voltage and with thermal resistance in the electrodes. Other models that require approximate or computed solutions yield results that are very close to the analytic solution when appropriate dimensionless variables are chosen. The dimensionless critical voltage as a function of dimensionless critical thickness is shown to be almost independent of electrical and thermal conductivity parameters. It is also found that the solution for the thick limit applies in most cases of physical importance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338097
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of Neutron Irradiation on the Thermal Conductivity of a Quartz Crystal at Low Temperature (1950)
    [s.l.] : Nature Publishing Group
    Nature 166 (1950), S. 864-866 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In the present experiments lattice defects, consisting of displaced atoms, have been produced in a quartz crystal by irradiation with fast neutrons in a pile, and we have measured the changes in conductivity after several successive periods of irradiation and after subsequent annealing. The extra ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/166864a0
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis of Si(C, N) nanoparticles by rapid laser polycondensation/crosslinking reactions of an organosilazane precursor (1992)
    Springer
    Journal of materials science 27 (1992), S. 3231-3238 
    Details
    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 A study has been made of basic mechanisms involved in the rapid synthesis of pre-ceramic and ceramic nanoparticle powders. In this process an aerosol, formed from an ultrasonically atomized liquid organosilazane monomer, [CH3SiHNH] n , is injected into the beam of an industrial CW CO2 laser. One critical feature examined was the rapid condensation of molecular species from the laser plume, in a process involving three-dimensional crosslinking polycondensation reactions. In accompanying studies, a model has been formulated to determine the laser plume temperature, the cooling rate of condensing species and the particle diameter. These are obtained by analytical solution of heat conduction, momentum and mass conservation equations that consider heat loss by gas conduction, radiation, evaporation and convection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01116018
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  • 9
    Electronic Resource
    Electronic Resource
    Effective thermal conductivity of a matrix with two kinds of inclusions (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 979-981 
    Details
    ISSN: 1572-9567
    Keywords: ceramics ; colloids composites ; conductivity ; pores ; resistivity ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Previous approximations for the effective conductivity of a matrix with inclusions of low conductivity, and for the effective resistivity of a matrix with inclusions of high conductivity, are combined to give the effective conductivity when both types of inclusions are present. This applies, for example, to a ceramic which contains both pores and metallic inclusions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01439200
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  • 10
    Electronic Resource
    Electronic Resource
    Scattering of phonons by vacancies (1987)
    Springer
    International journal of thermophysics 8 (1987), S. 737-750 
    Details
    ISSN: 1572-9567
    Keywords: phonons ; potassium chloride ; thermal resistance ; tin telluride ; vacancies ; zirconium carbide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The scattering of phonons by vacancies is estimated by a perturbation technique in terms of the missing mass and the missing linkages. An argument is given why distortion effects can be disregarded. The resonance frequency of the defect is sufficiently high so that resonance effects can be disregarded for phonons in the important frequency range for thermal conduction. The theory is applied to the thermal resistance by vacancies in cases where the vacancy concentration is known: potassium chloride with divalent cations, nonstoichiometric zirconium carbide, and tin telluride.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00500791
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