The thermal conductivity of sapphire between 0.4 and 4 °K

Wolfmeyer, M.W.; Dillinger, J. R.

doi:10.1016/0375-9601(71)90853-x

Cited by 18 publications

(6 citation statements)

References 7 publications

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“…In experiments, however, in addition to the expected behaviour κT −3 = constant, a remarkable increase in κT −3 below T * ∼ 0.1 K was detected. A similar deviation, but beginning near 2 K, was observed in sapphire [4]. There is still no satisfactory explanation for this phenomenon.…”

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confidence: 52%

“…We have shown that the thermal conductivity exhibits a crossover from κ ∼ T 2 to κ ∼ T 3 with T increasing. Thus, the biaxial WDD is a good candidate for the specific scatterer proposed in [4]. The results obtained allow us to explain the deviation of the thermal conductivity from a T 3 -dependence below 0.1K observed in LiF and N aCl.…”

mentioning

confidence: 63%

“…In particular, in [1] it was supposed that the measured increase can be caused by the onset of partial specular reflection from the lightly sandblasted walls. Similarly, it was suggested that [4] "a frequency independent scattering mechanism should be present in these samples which becomes ineffective below 1K".…”

mentioning

confidence: 98%

“…We considered the experimental results for LiF [1,2], N aCl [2], and sapphire [4]. Experimental data due to boundary-induced phonon scattering in LiF from [1] are shown in Fig.2.…”

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confidence: 99%

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Towards the grain boundary phonon scattering problem: evidence for a low-temperature crossover

Osipov

Krasavin

1998

J. Phys.: Condens. Matter

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The problem of phonon scattering by grain boundaries is studied within the wedge disclination dipole (WDD) model. It is shown that a specific q-dependence of the phonon mean free path for biaxial WDD results in a low-temperature crossover of the thermal conductivity, κ. The obtained results allow to explain the experimentally observed deviation of κ from a T 3 dependence below 0.1K in LiF and N aCl.The effect of low-angle grain boundaries on the thermal conductivity, κ, of LiF and N aCl over the temperature range 0.08-5 K has been investigated in [1,2]. The main conclusions are the following: (i) the boundaries are sessile, (ii) the dominant phonon-scattering process comes from static strain fields caused by boundaries, and (iii) the experimental results are compatible with predictions of the theoretical model [3] where a grain boundary is represented as a wall of edge dislocations. In experiments, however, in addition to the expected behavior κT −3 = const, a remarkable increase in κT −3 below T * ∼ 0.1K was detected. A similar deviation, but beginning near 2K, was observed in sapphire [4]. There is still no satisfactory explanation of this phenomenon. In particular, in [1] it was supposed that the measured increase can be caused by the onset of partial specular reflection from the lightly sandblasted walls. Similarly, it was suggested that [4] "a frequency independent scattering mechanism should be present in these samples which becomes ineffective below 1K".In 1955 Klemens [3] studied the problem of the scattering of lattice waves by grain boundaries within the Born approximation. Considering the grain boundary as an array of edge dislocations lying in the plane of the boundary, he found that the phonon mean free path is frequency independent. Hence a T 3 dependence of the thermal conductivity at low temperatures was associated with the boundary scattering. While this finding explains well the experimental results [1,2,4] above some characteristic temperature, T * , it fails to describe the observed anomaly below T * . It is important to note in this connection that the result [3] was obtained under assumption that the dislocation wall is infinitely long. For a finite wall of well separated dislocations the problem of the phonon scattering becomes difficult and is still unresolved.An alternative model for description of grain boundaries has been presented in [5]. It was proposed that grain boundaries being rather rotational than translational defects can be described more naturally by disclinations. Moreover, what is important, the far strain fields caused by wedge disclination dipoles (WDD) were found to agree with those from finite walls of edge dislocations [6,7]. For this reason, the WDD-based model allows us to study important effects due to finiteness of grain boundaries.Notice also that additional interest to this problem was inspired by recent consideration of disclinations and dipoles of disclinations in the context of metal glasses [8,9], graphite films [10], and nanostructures [11]. For example, an...

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confidence: 52%

mentioning

confidence: 63%

mentioning

confidence: 98%

“…We considered the experimental results for LiF [1,2], N aCl [2], and sapphire [4]. Experimental data due to boundary-induced phonon scattering in LiF from [1] are shown in Fig.2.…”

mentioning

confidence: 99%

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Towards the grain boundary phonon scattering problem: evidence for a low-temperature crossover

Osipov

Krasavin

1998

J. Phys.: Condens. Matter

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“…, where , is the thermal conductivity [9], is the heat capacity [10], and is the mass density, yielding . Heat transport up the cold finger to the SFHe bath above has a characteristic length scale , corresponding to a relaxation time constant .…”

Section: Heat Transport In the Sapphire Concentratormentioning

confidence: 99%

Superconducting Test Cavity With Dielectric Concentrator for High Q, High Surface Field

Pogue

Blackburn

McIntyre

et al. 2009

IEEE Trans. Appl. Supercond.

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A superconducting test cavity and cryostat are being developed to support the testing of round wafer samples of new superconducting materials. The cavity is designed to test these samples in surface fields up to and beyond the BCS limit of Nb. The design is optimized to produce maximum surface field on the sample compared with that elsewhere in the cavity. It operates in the TE 011 mode. A dielectric hemisphere of low-loss sapphire is located just above the wafer surface and serves to concentrate the surface field. The sapphire is cooled by a column of superfluid He, with sufficient heat transport to maintain high Q throughout the rf pulse. It should be possible to test a sample to twice the BCS limit of Nb while measuring the rf surface resistance of the sample.

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Lattice Thermal Conductivity of Sapphire in the Temperature Range 0.4 to 4.0 °K

Dubey

1972

Physica Status Solidi (b)

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The thermal conductivity of sapphire between 0.4 and 4 °K

Cited by 18 publications

References 7 publications

Towards the grain boundary phonon scattering problem: evidence for a low-temperature crossover

Towards the grain boundary phonon scattering problem: evidence for a low-temperature crossover

Superconducting Test Cavity With Dielectric Concentrator for High Q, High Surface Field

Lattice Thermal Conductivity of Sapphire in the Temperature Range 0.4 to 4.0 °K

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