SPECIFIC HEATS OF MANGANESE AND BISMUTH AT LIQUID HYDROGEN TEMPERATURES

1949 ◽  
Vol 27a (2) ◽  
pp. 9-16 ◽  
Author(s):  
L. D. Armstrong ◽  
H. Grayson-Smith
Keyword(s):  
Specific Heat ◽  
Accurate Determination ◽  
Theoretical Formula ◽  
Electronic Specific Heat ◽  
Debye Function ◽  
Specific Heats ◽  
Simple Cubic ◽  
Limited Temperature ◽  
Specific Heat Coefficient

New measurements of the specific heats of manganese and bismuth in the temperature range 14° to 22° K. are reported. The specific heats of these metals are compared with theory. In both cases the approximate theoretical formula[Formula: see text]where CD(x) is the Debye function, is accurately obeyed over the limited temperature region concerned. However, comparison with measurements at other temperatures shows that this may lead to erroneous conclusions. For manganese a precise conclusion is not possible, and it is estimated that the electronic specific heat coefficient A lies between 0.0035 and 0.0040, while θ varies with temperature from 365 to 390 degrees. For bismuth it is concluded that the electronic specific heat is negligible. This permits an accurate determination of θ, and it is found that the variation of θ with temperature is remarkably similar to that predicted by Blackman for a simple cubic lattice.

Specific heat of InBi below 30 K

1981 ◽  
Vol 59 (4) ◽  
pp. 567-575 ◽  
Author(s):  
Douglas L. Martin
Keyword(s):  
Specific Heat ◽  
Debye Temperature ◽  
Thermal Contact ◽  
Adiabatic Calorimeter ◽  
Electronic Specific Heat ◽  
Good Thermal Contact ◽  
Debye Temperatures ◽  
Isoperibol Calorimeter ◽  
Specific Heat Coefficient

There was difficulty in establishing good thermal contact with InBi, a very anisotropic material. This is not believed to have affected results from the 2.5–30 K adiabatic calorimeter. However, results from the 0.35–3 K isoperibol calorimeter are a few percent high in the overlap range owing to uncompensated heat loss during heating periods. Consequently there is some uncertainty in the determination of the electronic specific heat but little uncertainty in Debye temperatures above 1 K (because the lattice specific heat is so large). Despite the great anisotropy, mass-layering, and easy cleaving in one direction, the variation of Debye temperature with temperature is quite normal, there being no evidence of two-dimensional behavior (cf. graphite). The preferred analysis gives the electronic specific heat coefficient as 97.1 ± 0.8 μcal K−2 g-at.−1 (406 ± 3 μJ K−2 g-at.−1) and the low temperature limiting value of Debye temperature as 139.8 ± 0.4 K.

Low temperature specific heats of zinc alloyed with silver

1975 ◽  
Vol 343 (1634) ◽  
pp. 363-374 ◽  
Keyword(s):  
Low Temperature ◽  
Fermi Level ◽  
Specific Heat ◽  
Debye Temperature ◽  
Density Of States ◽  
Electronic Specific Heat ◽  
Pure Zinc ◽  
Specific Heats ◽  
Complete Breakdown ◽  
Specific Heat Coefficient

Measurements of the electronic specific heat coefficient and of the limiting Debye temperature are reported for pure zinc and for two n-phase alloys containing 2 at. % and 4 at. % silver in zinc, respectively. After a correction for electron-phonon enhancement the electronic specific heat coefficient for pure zinc differs by only a small percentage from the calculated value reported in the literature on the basis of a band calculation. The results for the alloys show a decreasing trend of the density of states at the Fermi level when silver is added to zinc. This is contrary to a prediction based on a rigid band approach. Hence, the results indicate a complete breakdown of the rigid band condition on alloying. The reasons for this are most likely associated with the influence of the d band electrons or with charge distribution effects between solute and solvent atoms.

Experimental evidence for the Fermi surface overlap effect in ε-phase Ag—Zn alloys, obtained from low temperature specific heats

1975 ◽  
Vol 343 (1634) ◽  
pp. 375-387 ◽  
Keyword(s):  
Theoretical Model ◽  
Low Temperature ◽  
Specific Heat ◽  
Brillouin Zone ◽  
Band Gaps ◽  
Electronic Specific Heat ◽  
Specific Heats ◽  
Ε Phase ◽  
Specific Heat Coefficient ◽  
Zn Alloys

Measurements of the electronic specific heat coefficient and of the limiting Debye temperature are reported for ten Ag-Zn alloys in the range of the h.e.p. ε-phase. After a correction for the electron-phonon enhancement, the trend of the electronic specific heat coefficient is consistent with a nearly rigid band behaviour, showing a general decrease of the density of states at the Fermi level when the corners of the Brillouin zone are filled. A slight deviation from this trend occurs at electron concentration values exceeding approximately 1.85 5 , in agreement with other measured properties and confirming a theoretical model involving overlaps of electrons across the {00.2} planes of the Brillouin zone. The estimated band gaps are of the order of 2 eV. I t appears that whereas in the dilute rj-phase alloys of zinc with silver the rigid band condition is not valid the opposite is true in the concentrated ε-phase alloys.

Specific heat below 3 °K of a gold–zinc and a gold–indium alloy

1969 ◽  
Vol 47 (10) ◽  
pp. 1077-1081 ◽  
Author(s):  
Douglas L. Martin
Keyword(s):  
Specific Heat ◽  
Face Centered Cubic ◽  
Electronic Specific Heat ◽  
Confidence Limits ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Atomic Silver ◽  
Face Centered ◽  
Specific Heat Coefficient ◽  
Limiting Value

Face-centered-cubic alloys of gold with 10 atomic % zinc (divalent) and 10 atomic % indium (trivalent), respectively, were measured in the range 0.4 to 3.0 °K. The coefficients of the nuclear specific-heat term were 1.80 ± 0.07 μcal °K/g atom for AuZn and 1.29 ± 0.06 μcal °K/g atom for AuIn (95% confidence limits). For a gold–10 atomic % silver (monovalent) alloy (Martin 1968) the nuclear term was 0.44 μcal °K/g atom. These results show that electric field gradients in alloys are not simply proportional to the valence difference of the components, a conclusion which may be drawn from NMR results. For the AuZn alloy the electronic specific-heat coefficient (γ) is 153.4 ± 0.7 μcal/°K2 g atom and the limiting value of the Debye temperature (θ0c) is 177.0 ± 0.5 °K. For the AuIn alloy γ is 185.9 ± 0.7 μcal/°K2 g atom and θ0c is 159.1 ± 0.3 °K.

Specific heats of polymer powders by differential scanning calorimetry

1982 ◽  
Vol 60 (14) ◽  
pp. 1853-1856 ◽  
Author(s):  
Eva I. Vargha-Butler ◽  
A. Wilhelm Neumann ◽  
Hassan A. Hamza
Keyword(s):  
Differential Scanning Calorimetry ◽  
Specific Heat ◽  
Scanning Calorimetry ◽  
Temperature Range ◽  
Specific Heats ◽  
Powdered Form ◽  
Polymer Powders

The specific heats of five polymers were determined by differential scanning calorimetry (DSC) in the temperature range of 300 to 360 K. The measurements were performed with polymers in the form of films, powders, and granules to clarify whether or not DSC specific heat values are dependent on the diminution of the sample. It was found that the specific heats for the bulk and powdered form of the polymer samples are indistinguishable within the error limits, justifying the determination of specific heats of powders by means of DSC.

Hole density dependence of the low temperature electronic specific heat coefficient of La2-xSrxCaCu2O6 with weakly localized electrons

1993 ◽  
Vol 209 (4) ◽  
pp. 553-558 ◽  
Author(s):  
Takashi Nishikawa ◽  
Shin-ichi Shamoto ◽  
Masafumi Sera ◽  
Masatoshi Sato ◽  
Shigeki Ohsugi ◽  
...  
Keyword(s):  
Low Temperature ◽  
Specific Heat ◽  
Density Dependence ◽  
Hole Density ◽  
Electronic Specific Heat ◽  
Specific Heat Coefficient ◽  
Localized Electrons

Spin Disorder Resistivity and Electronic Specific Heat of Gd4(Co1-xCux)3 Compounds

2008 ◽  
Vol 587-588 ◽  
pp. 333-337
Author(s):  
T.M. Seixas ◽  
M.A. Salgueiro da Silva ◽  
O.F. de Lima ◽  
J. Lopez ◽  
Hans F. Braun ◽  
...  
Keyword(s):  
Specific Heat ◽  
Linear Dependence ◽  
Magnetic Moments ◽  
Spin Fluctuations ◽  
Electronic Specific Heat ◽  
Spin Disorder ◽  
Structure Changes ◽  
Thermal Disorder ◽  
Specific Heat Coefficient ◽  
Electron Band Structure

In this work, we present a study of the spin disorder resistivity ( ρm∞) and the electronic specific heat coefficient ( γ) in Gd4(Co1-xCux)3 compounds, with x = 0, 0.05, 0.10, 0.20, 0.30. The experimental results show a strongly non-linear dependence of ρm∞ on the de Gennes factor which, in similar intermetallic compounds, is usually attributed to the existence of spin fluctuations on the Co 3d bands and its amplification by the thermal disorder of the Gd magnetic moments through the Gd-Co exchange coupling. Using a novel combined analysis of ρm∞ and γ, we show, however, that only electron band structure changes are involved in the anomalous behaviour of ρm∞ and that a linear dependence of ρm∞ on the de Gennes factor is obtained when the variation of the effective mass is properly taken into account.

Effect of ordering on the specific heat of Cu3Au below 3 °K

1968 ◽  
Vol 46 (8) ◽  
pp. 923-927 ◽  
Author(s):  
Douglas L. Martin
Keyword(s):  
Elastic Constant ◽  
Specific Heat ◽  
Electric Quadrupole ◽  
Quadrupole Moments ◽  
Electronic Specific Heat ◽  
Electric Field Gradients ◽  
Specific Heats ◽  
Disordered Lattice ◽  
Field Gradients ◽  
Lattice Specific Heat

Ordering reduces the nuclear, electronic, and lattice specific heats. The change in nuclear specific heat supports the hypothesis that this term in the specific heat arises from the interaction of nuclear electric quadrupole moments with electric field gradients in the disordered lattice. The small (3.5%) change in the electronic specific heat suggests little change in the Fermi surface on ordering. The change in the lattice specific heat is greater than expected from elastic constant measurements on ordered and disordered Cu3Au.

Electronic specific heat coefficient and magnetic entropy of icosahedral Mg-RE-Zn (RE=Gd, Tb and Y) quasicrystals

1995 ◽  
Vol 7 (22) ◽  
pp. 4183-4191 ◽  
Author(s):  
Y Hattori ◽  
K Fukamichi ◽  
K Suzuki ◽  
A Niikura ◽  
A P Tsai ◽  
...  
Keyword(s):  
Specific Heat ◽  
Electronic Specific Heat ◽  
Magnetic Entropy ◽  
Specific Heat Coefficient
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