scholarly journals The Specific Heat and Thermal Conductivity of Graphite

1953 ◽  
Vol 6 (4) ◽  
pp. 405 ◽  
Author(s):  
PG Klemens
Keyword(s):  
Thermal Conductivity ◽  
Specific Heat ◽  
Low Temperatures ◽  
Two Dimensional ◽  
Longitudinal Waves

The specific heat of graphite is discussed in terms of a modified Debye treatment. It is shown that the contribution from the longitudinal waves varies as T3 below 45 �K, and as T2 at higher temperatures, whereas the usual two-dimensional treatment leads to a T2 variation at all low temperatures. Similarly the transverse contribution varies as T3 at lowest temperatures, But above 10 �K it varies as T2.

Specific heat of ordered and isotopically disordered lattices

1978 ◽  
Vol 56 (10) ◽  
pp. 1390-1394
Author(s):  
K. P. Srivastava
Keyword(s):  
Specific Heat ◽  
Low Temperatures ◽  
Numerical Study ◽  
Three Dimensional ◽  
Constant Volume ◽  
Nearest Neighbour ◽  
Two Dimensional ◽  
Appreciable Difference ◽  
Substantial Change ◽  
Neighbour Interaction

An extensive numerical study on specific heat at constant volume (Cv) for ordered and isotopically disordered lattices has been made. Cv at various temperatures for ordered and disordered linear and two-dimensional lattices have been compared and no appreciable difference in Cv between these two structures has been observed. Effect of concentration of light atoms on Cv for three-dimensional isotopically disordered lattices has also been shown.In spite of taking next-nearest-neighbour interaction into account, no substantial change in Cv between the ordered and isotopically disordered linear lattices has been found. It is shown that the low lying modes contribute substantially at low temperatures.

Specific Heat and Thermal Conductivity of Superconducting UBe13and UPt3at Very Low Temperatures

1987 ◽  
Vol 26 (S3-2) ◽  
pp. 1217 ◽  
Author(s):  
H. R. Ott ◽  
E. Felder ◽  
A Bernasconi ◽  
Z. Fisk ◽  
J. L. Smith ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Specific Heat ◽  
Low Temperatures

The thermal conductivities of some dielectric solids at low temperatures (Experimental)

1951 ◽  
Vol 208 (1092) ◽  
pp. 90-108 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Specific Heat ◽  
Temperature Variation ◽  
Temperature Region ◽  
Low Temperatures ◽  
Quartz Crystal ◽  
Corundum Crystal ◽  
Before And After ◽  
Dielectric Solids

An apparatus is described in which the thermal conductivity of solids can be determined at any temperature between 2 and 90°K. Several glasses and dielectric crystals have been measured. It had previously been found that at high temperatures the conductivity of glasses is proportional to the specific heat, but at low temperatures it falls off more slowly than the specific heat. The present experiments show that there is a temperature region in which the conductivity is nearly independent of temperature. A similar variation of conductivity is found for the thermo-plastic Perspex. The effect of lattice defects in crystals was studied by measuring the thermal conductivity of a quartz crystal before and after successive periods of neutron irradiation. After prolonged irradiation the conductivity approached, in both magnitude and temperature variation, that of quartz glass. Subsequent heating produced a substantial recovery in the conductivity. The results on both glasses and on crystals can be explained by the theory developed by Klemens (1951). Further measurements made on a corundum crystal confirm the importance of the ‘Umklapp’ processes, postulated by Peierls, in causing thermal resistance.

Critical Phenomena at the Antiferromagnetic Transition in MnO

1999 ◽  
Vol 602 ◽  
Author(s):  
B.F. Woodfield ◽  
J.L. Shapiro ◽  
R. Stevens ◽  
J. Boerio-Goates ◽  
M.L. Wilson
Keyword(s):  
Ising Model ◽  
Critical Exponent ◽  
Specific Heat ◽  
Temperature Dependence ◽  
Low Temperatures ◽  
Applied Pressure ◽  
Polycrystalline Sample ◽  
Type Ii ◽  
Two Dimensional ◽  
Antiferromagnetic Transition

AbstractThe specific heat of a polycrystalline sample of MnO was measured from T ≈ 1 K to T ≈ 400 K using two different experimental apparatuses at zero applied pressure. Features revealed by the data include a hyperfine contribution due to the Mn nuclei, a T2 temperature dependence at low temperatures due to the type-II antiferromagnetic magnon contribution, and a sharp but well defined antiferromagnetic transition (TN = 117.7095 K) that is clearly second order in nature. The critical exponent, α, deduced from the transition is consistent with a two dimensional Ising model. The specific heat of MnO is also compared with recent results on the type-A antiferromagnet LaMnO3.

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