Band Structure of Monovalent Metals and Their Alloys

1960 ◽  
Vol 13 (2) ◽  
pp. 238 ◽  
Author(s):  
PG Klemens
Keyword(s):  
Band Structure ◽  
Fermi Surface ◽  
Physical Properties ◽  
Specific Heat ◽  
Thermoelectric Power ◽  
Quantitative Comparison ◽  
Electronic Specific Heat ◽  
Phonon Drag ◽  
Conduction Properties

The consequences of the Bloch theory of the conduction properties of metals can be evaluated only for a band of spherical Fermi surface, isotropic in all respects. Quantitative comparison with observations is thus possible only for the monovalent metals. It appears that even the monovalent metals do not satisfy this requirement, but that their Fermi surface departs significantly from sphericity. The information derived from the various conduction properties and the electronic specific heat is discussed, paying attention to Umklapp processes and phonon drag effects. The thermoelectric power is difficult to interpret. Systematic measurements of the changes of various physical properties on alloying may provide useful information.

On The Thermoelectric Power And Transport Properties Of Quasicrystals

1998 ◽  
Vol 553 ◽  
Author(s):  
F. Cyrot-Lackmann
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Fermi Surface ◽  
Physical Properties ◽  
Thermoelectric Power ◽  
Thermoelectric Materials ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Phonon Drag ◽  
Crude Estimate

Stable quasicrystals exhibit specific and unusual physical properties, such as, diamagnetism, low electrical conductivity, low thermal conductivity, and large themoelectric power at room temperature. These properties can be understood with a Bragg's reflexions scheme due to their dense filled reciprocal space.This leads to small gaps on the Fermi surface (some tenths of eV), much narrower than the usual Hume-Rothery ones (of order of 0.5 eV) which explain their stability. These gaps lead to the existence of quasi Umklapp processes, crucial for the interpretation of thermoelectric power. In some cases, the positive phonon drag contribution due to Umklapp processes, add with the electronic one's and dominates at room temperature with a large positive thermoelectric power. A crude estimate of the figure of merit gives some hope for applications of some quasicrystals and high approximants as new thermoelectric materials.

Nodal gap behavior of Bi2Sr2−xLnxCuO6+δ (Ln = La, Eu) investigated by specific heat measurements

2015 ◽  
Vol 29 (25n26) ◽  
pp. 1542014 ◽  
Author(s):  
M. Shimizu ◽  
Y. Moriya ◽  
S. Baar ◽  
N. Momono ◽  
Y. Amakai ◽  
...  
Keyword(s):  
Low Temperature ◽  
Magnetic Fields ◽  
Fermi Surface ◽  
Specific Heat ◽  
Excitation Spectrum ◽  
Cuprate Superconductors ◽  
Electronic Excitation ◽  
Linear Term ◽  
Electronic Specific Heat ◽  
Low Temperature Specific Heat

We performed low-temperature specific heat measurements on slightly underdoped samples of monolayer cuprate superconductors [Formula: see text] (Ln = La, Eu, Ln-Bi2201) under magnetic fields [Formula: see text]. In La-Bi2201, the coefficient [Formula: see text] of [Formula: see text]-linear term in the electronic specific heat [Formula: see text] at [Formula: see text] shows [Formula: see text] dependence, as expected in [Formula: see text] -wave superconductors. In Eu-Bi2201, [Formula: see text] shows almost the same [Formula: see text] dependence as that of La-Bi2201 below [Formula: see text] T, while [Formula: see text] is suppressed above [Formula: see text] T and deviates downward from the [Formula: see text] curve of La-Bi2201. This result suggests the the gap and the electronic excitation spectrum near nodes are modified in Eu-Bi2201 except the region of the Fermi surface in the immediate vicinity of nodes.

The specific heat of metals and alloys at low temperatures

1957 ◽  
Vol 240 (1222) ◽  
pp. 321-332 ◽  
Keyword(s):  
Fermi Surface ◽  
Specific Heat ◽  
Liquid Helium ◽  
Brillouin Zone ◽  
Low Temperatures ◽  
Metals And Alloys ◽  
Thermal Excitation ◽  
Electronic Specific Heat ◽  
Conduction Electrons ◽  
Elastic Shear

The effect of thermal excitation of the conduction electrons on the elastic shear constants is investigated in a metal in which the Fermi surface lies close to the Brillouin-zone boundaries. It is shown that in these circumstances electron-lattice interaction leads to an addi­tional term in the specific heat, linear in the temperature in the liquid-helium range, which, therefore, augments the pure electronic specific heat. The variation in magnitude of this linear term is considered in the α-brasses. It is suggested that this is the physical effect underlying the peculiarities of the ‘electronic’ specific heat of these alloys.

The band structure of aluminium I. Determination from experimental data

1957 ◽  
Vol 240 (1222) ◽  
pp. 340-353 ◽  
Keyword(s):  
Experimental Data ◽  
Low Temperature ◽  
Band Structure ◽  
Fermi Surface ◽  
Specific Heat ◽  
Electron Energy ◽  
Brillouin Zone ◽  
Free Electron ◽  
The Third ◽  
Low Temperature Specific Heat

The band structure and particularly the shape of the Fermi surface are deduced mainly from the available experimental data on the de Haas-van Alphen and anomalous skin effects, and from the low-temperature specific heat. Since these data are rather incomplete, it is found necessary to use in conjunction with them a theoretical band-structure calcula­tion, which, however, unavoidably contains rough approximations. Except near the surface of.the Brillouin zone, E (k) is found to be very close to the free-electron energy. The first zone is found to contain 3.6 × 10 -3 holes per atom around the zone comers. There is overflow of electrons into the second zone across all the zone faces, and these regions of the Fermi distribution are joined together near the centres of the zone edges; the third zone contains a very small number of electrons.

ON THE FERMI SURFACE OF BETA BRASS

1966 ◽  
Vol 44 (8) ◽  
pp. 1787-1793 ◽  
Author(s):  
J. -P. Jan
Keyword(s):  
Fermi Surface ◽  
Specific Heat ◽  
Brillouin Zone ◽  
Present Model ◽  
Energy Gap ◽  
Electronic Specific Heat ◽  
Cone Model ◽  
Best Fit ◽  
Structure Calculations ◽  
Good Agreement

Results of de Haas – van Alphen effect measurements on ordered β′-CuZn (50 at.% Zn) provide the area of contact of the Fermi surface with the faces of the second (dodecahedral) Brillouin zone. If the energy gaps at the faces of the first (cubic) Brillouin zone are ignored, a 12-cone model can be worked out. An energy gap of 3.49 eV at the second-zone faces and an effective mass m* = 1.045me, provide the best fit between the 12-cone model, the area of contact, and the measured electronic specific heat. The gap is in good agreement with present band-structure calculations. The first-zone gaps do give rise to de Haas – van Alphen oscillations, but their neglect in the present model should not affect the calculated electronic specific heat appreciably.

Electronic specific heat of aluminum-based alloys

1970 ◽  
Vol 48 (12) ◽  
pp. 1504-1513 ◽  
Author(s):  
J. P. Carbotte ◽  
P. T. Truant ◽  
R. C. Dynes
Keyword(s):  
Band Structure ◽  
Specific Heat ◽  
Electron Concentration ◽  
Free Electron ◽  
Strong Dependence ◽  
Direct Consequence ◽  
Electronic Specific Heat ◽  
Mass Renormalization ◽  
Electron Model ◽  
Free Electron Model

It has recently been found that in aluminum-based alloys, the change in the logarithm of the specific heat with the logarithm of the electron concentration is more than three times the value expected from free electron model considerations. This is not likely to be a result of band structure. We suggest that this experimental behavior is a direct consequence of the strong dependence of the electron–phonon mass renormalization of the specific heat on the electron concentration.

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