Thermal conductivity for defect and boundary scattering of phonons at low temperatures

1977 ◽  
Vol 79 (2) ◽  
pp. K153-K155 ◽  
Author(s):  
Th. F. Nonnenmacher ◽  
R. Wunderle
Keyword(s):  
Thermal Conductivity ◽  
Low Temperatures ◽  
Boundary Scattering

The thermal conductivity of diamond at low temperatures

1953 ◽  
Vol 220 (1141) ◽  
pp. 171-183 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Temperature Variation ◽  
Finite Length ◽  
Low Temperatures ◽  
Room Temperature ◽  
Experimental Results ◽  
Theoretical Treatment ◽  
Type I ◽  
Boundary Scattering ◽  
Crystal Boundaries

The thermal conductivity of a type I diamond has been measured between 2° K and room temperature. Above 100° K the temperature variation of conductivity accords with Peierls’s theory of Umklapp processes. To account for the results at the lowest temperatures it is necessary to assume that some specular reflexion of phonons occurs at the crystal boundaries. Casimir’s theoretical treatment of boundary scattering has been extended to take into account the finite length of specimens and the smoothness of the crystal walls, and the experimental results show that at 3° K the proportion of specular reflexions is as great as 40%. Between 50 and 100° K the conductivity is considerably less than that calculated for an ideal diamond, and some conclusions are drawn as to the imperfections which cause this discrepancy.

scholarly journals Analysis of the Effect of Resonant Phonon Scattering on the Thermal Conductivity of CaF2

1976 ◽  
Vol 29 (2) ◽  
pp. 19 ◽  
Author(s):  
PRW Hudson ◽  
EE Gibbs
Keyword(s):  
Thermal Conductivity ◽  
Low Temperatures ◽  
Phonon Scattering ◽  
Low Frequency ◽  
Resonant Scattering ◽  
Boundary Scattering ◽  
Scattering Mechanism ◽  
Scattering Mechanisms ◽  
Phonon Conduction

An analysis is presented of the various phonon contributions to the thermal conductivity of CaF2 doped with 1�0% and 0�1 % of yttrium or thulium. The broad phonon resonant scattering term is found to reduce the low frequency phonon conduction significantly. This is responsible for the relatively stronger suppression of the conductivity at low temperatures in the phonon boundary scattering region. Thus broad quasilocalized phonon resonant scattering mechanisms have a similar effect to phonon precipitate scattering. It also follows that, in the case of a broad resonant scattering mechanism, a dip will not necessarily be seen in the conductivity.

The Evaluation of TiTe2 as a Diffusion Barrier in the Formation of Low Thermal Conductivity Nanolaminates with Bi2Te3 and Sb2Te3

2010 ◽  
Vol 74 ◽  
pp. 38-47
Author(s):  
Clay Mortensen ◽  
Paul Zschack ◽  
David C. Johnson
Keyword(s):  
Thermal Conductivity ◽  
Diffusion Barrier ◽  
Self Assembly ◽  
Low Temperatures ◽  
Annealing Temperature ◽  
The Self ◽  
High Angle ◽  
X Ray Diffraction ◽  
Amorphous Precursor ◽  
X Ray

The evolution of designed [(Ti-Te)]x[(Sb-Te)]y, [(Bi-Te)]x[(Sb-Te)]y, [(Ti-Te)]w[(Bi-Te)]x[(Sb-Te)]y and [(Ti-Te)]w[(Bi-Te)]x[(Ti-Te)]y[(Sb-Te)]z precursors were followed as a function of annealing temperature and time using both low and high angle x-ray diffraction techniques to probe the self assembly into nanolaminate materials. The [(Bi-Te)]x[(Sb-Te)]y precursors were found to interdiffuse at low temperatures to form a (BixSb1-x)2Te3 alloy. The [(Ti-Te)]x[(Bi-Te)]y and [(Ti-Te)]x[(Sb-Te)]y precursors formed ordered nanolaminates [{(TiTe2)}1.35]x[Bi2Te3]y and [{(TiTe2)}1.35]x[Sb2Te3]y respectively. The [(Ti-Te)]w[(Bi-Te)]x[(Sb-Te)]x precursors formed [{(TiTe2)}1.35]w[(Bi0.5Sb0.5)2Te3]2x nanolaminates on annealing, as the bismuth and antimony layers interdiffused. Over the range of TiTe2 thicknesses used in [(Ti-Te)]w[(Bi-Te)]x[(Ti-Te)]y[(Sb-Te)]z precursors, Bi and Sb were found to interdiffuse through the 2-4 nm thick Ti-Te layers, resulting in the formation of (BixSb1-x)2Te3 alloy layers as part of the final nanolaminated products. When the Bi-Te and Sb-Te thicknesses were equal in the amorphous precursors, symmetric [{(TiTe2)}1.35]m[(Bi0.5Sb0.5)2Te3]n nanolamiantes were formed. When the thicknesses of Bi-Te and Sb-Te layers were not equal in the amorphous precursor, asymmetric [(TiTe2)1.35]m[(BixSb1-x)2Te3]n[(TiTe2)1.35]m[(BixSb1-x)2Te3]p nanolaminates were formed. These results imply that to form (A)w(B)x(C)y nanolaminates using designed layered precursors all three components must be immiscible. To form (A)x(B)y(A)x(C)z nanolaminates, the components must be immiscible or the precursor to the A component and the A component itself must be an effective interdiffusion barrier preventing B and C from mixing.

Thermal Property Measurements on Biological Materials at Subzero Temperatures

1991 ◽  
Vol 113 (4) ◽  
pp. 423-429 ◽  
Author(s):  
Xuemei Bai ◽  
David E. Pegg
Keyword(s):  
Thermal Conductivity ◽  
Low Temperatures ◽  
The Self ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Low Viscosity ◽  
Subzero Temperatures ◽  
Liquid Samples ◽  
Thermal Probes ◽  
Low Ionic Strength

The self-heated thermistor technique was used to measure the thermal conductivity and thermal diffusivity of biomaterials at low temperatures. Thermal standards were selected to calibrate the system at temperatures from −10°C to −70°C. The thermal probes were constructed with a convection barrier which eliminates convection inside liquid samples of low viscosity, without affecting the conductivity and diffusivity results. Using this technique, the thermal conductivity and diffusivity of two organ perfusates (HP5 and HP5 + 2M glycerol), one kidney phantom (a low ionic strength gel), as well as rabbit kidney cortex have been measured from −10°C to −70°C.

Sign in / Sign up

Export Citation Format

Share Document