Thermo-electricity at low temperatures VII. Thermo-electricity of the alkali metals between 2 and 20 °K

In earlier work, the absolute thermo-electric force, E of the alkalis was measured from about 60°K down to about 4°K. The absolute thermo-electric power ( S=dE/dT ) could then be derived with fair accuracy down to perhaps 8°K. The thermo-electric power of all the alkali metals has now been measured directly between 2 and 20°K, and the Thomson heats derived therefrom. The results are compared with the theory both of the ‘normal’ thermo-electric power and the Gurevich or ‘phonon-drag’ effect. It is clear from the work that experiments below 1 °K in this field will be of much interest and a programme has been started in this temperature range.

Download Full-text

Thermo-electricity at low temperatures III. The absolute scale of thermo-electric power: a critical discussion of the present scale at low temperatures and preliminary measurements towards its redetermination

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1955.0194 ◽

1955 ◽

Vol 231 (1187) ◽

pp. 534-544 ◽

Cited By ~ 7

Keyword(s):

Electric Power ◽

Low Temperatures ◽

Alkali Metals ◽

Present Theory ◽

Critical Discussion ◽

Electric Force ◽

Thermo Electric ◽

Absolute Scale ◽

The Absolute

In order to compare exactly the present theory of thermo-electric power in metals with the behaviour of the simple alkali metals, particularly sodium, at low temperatures, it is necessary to know the absolute thermo-electric, power of one single conductor. There has been only one such determination of an absolute scale of thermo-electric power, and this was derived 23 years ago as the outcome of measurements which had been made primarily for other purposes. As measurements of the thermo-electric force of the alkali metals at low temperatures have recently become available, it is appropriate now to review critically the experimental basis of that scale. In view of new experimental evidence on the behaviour of the thermo-electric power of superconductors just above the transition point which has appeared in the last few years, it appears that a redetermination of the scale is necessary, at least at low temperatures. In this paper the present absolute scale of thermo-electric force is critically discussed particularly in relation to preliminary measurements towards its redetermination.

Download Full-text

Thermo-electricity at low temperatures VIII. Thermo-electricity of the alkali metals below 2°K

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1960.0112 ◽

1960 ◽

Vol 256 (1286) ◽

pp. 334-358 ◽

Cited By ~ 18

Keyword(s):

Electric Power ◽

Low Temperatures ◽

Alkali Metals ◽

Electric Force ◽

Thermo Electric ◽

Previous Part ◽

Adiabatic Demagnetization ◽

The Absolute ◽

Theoretical Developments

In the previous part (VII) the absolute thermo-electric power ( S ) of all the alkali metals was measured directly between 2 and 20°K. Measurements have now been made of the absolute thermo-electric force, E , of all the alkali metals below 2°K and down to about 0.1°K by means of adiabatic demagnetization techniques. The absolute thermo-electric power, S , is derived with fair accuracy from these results ( S = d E /d T ). The results are compared with theoretical developments, particularly those of Bailyn and Ziman.

Download Full-text

Thermo-electricity at low temperatures. VI. A redetermination of the absolute scale of thermo-electric power of lead

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1958.0078 ◽

1958 ◽

Vol 245 (1241) ◽

pp. 213-221 ◽

Cited By ~ 105

Keyword(s):

Electric Power ◽

Low Temperatures ◽

Alkali Metals ◽

Small Region ◽

Superconducting Transition ◽

Thermo Electric ◽

Metallic Conductor ◽

Direct Measurements ◽

The Absolute ◽

Sodium And Potassium

In order to compare the fundamental theory of thermo-electricity at low temperatures with the behaviour of the ‘simple’ alkali metals (in particular of sodium and potassium) it is essential to have an accurate knowledge of the absolute thermo-electric power of one pure metallic conductor against which the measurements can be made. We have accordingly determined the absolute thermo-electric power of zone-purified lead up to 18°K by direct measurements against the superconductor Nb 3 Sn. The new measurements, because of the high superconducting transition temperature of Nb 3 Sn, leave only the very small region between 18 and 20°K in which the Thomson heat of lead must be interpolated to join the values obtained by Borelius and co-workers in earlier work, in order to extend the new scale of absolute thermo-electric power of lead up to room temperature. The variation of the Thomson heat of lead as a function of temperature below 20°K appears to be of some intrinsic interest.

Download Full-text

Low-temperature transport properties of the alkali metals II. The transport coefficients

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1961.0185 ◽

1961 ◽

Vol 264 (1316) ◽

pp. 60-87 ◽

Cited By ~ 34

Keyword(s):

Fermi Surface ◽

Alkali Metals ◽

Transport Coefficients ◽

Direct Calculation ◽

Zone Boundary ◽

Phonon Drag ◽

Drag Effect ◽

Thermo Electric ◽

Sodium And Potassium ◽

The Ideal

The theory of part I (Collins 1961) is applied to the direct calculation of the ‘ideal’ electrical and thermal resistivities and ‘phonon drag’ thermo-electric power, of the alkali metals. All three coefficients depend, in magnitude and as functions of temperature, on the shape of the Fermi surface and on the lattice spectrum. If it is assumed that the latter is identical in form for all metals in the group, the observed transport coefficients are consistent with a Fermi surface which is quite distorted in lithium, becomes nearly spherical in sodium and potassium, and is again distorted in rubidium and caesium. The argument is not sufficiently accurate to discriminate between s -like and p -like symmetry in each case, nor to decide whether the Fermi surface actually touches the zone boundary; the phonon drag effect is also very sensitive to the purity of the specimen.

Download Full-text

On the thermo-electric power of metals

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1955.0069 ◽

1955 ◽

Vol 228 (1175) ◽

pp. 568-574 ◽

Cited By ~ 10

Keyword(s):

Electric Power ◽

Alkali Metals ◽

Phonon Scattering ◽

Opposite Sign ◽

Order Effects ◽

Lattice Distribution ◽

Thermo Electric ◽

The One ◽

Electric Effect ◽

Electron Phonon Scattering

Makinson’s extension of Wilson’s treatment of the second-order effects in metals is used to derive an expression for the contribution of the lattice current to the thermo-electric power of metals at those temperatures where electron-phonon scattering predominates. It is found that in this temperature region one may expect the thermo-electric effect to show a sign opposite to the one which follows from the simple electron theory of metals. This is because the term due to the departure from equilibrium of the lattice distribution is larger than the usual term and is of opposite sign. If the temperature is greatly decreased or increased, the usual term predominates. The effect discussed may have a bearing on the behaviour of the thermo-electric power of the alkali metals, although it cannot explain this behaviour completely.

Download Full-text

Studies On The Intermetallic Semiconductor RuAl2

MRS Proceedings ◽

10.1557/proc-512-245 ◽

1998 ◽

Vol 512 ◽

Author(s):

V. Ponnambalam ◽

U. V. Varadaraju

Keyword(s):

Electric Power ◽

Figure Of Merit ◽

Ladder Structure ◽

Thermo Electric ◽

Temperature Range ◽

Arc Melting ◽

Maximum Value ◽

Melting Technique ◽

Increasing Temperature ◽

Power Measurements

ABSTRACTThe intermetallic compound RuAl2 with Nowotny chimney-ladder structure is synthesized using arc melting technique. The electrical resistity and thermo electric power measurements were carried out in the temperature range 300–1000K. The resistivity increases with increasing temperature and reaches a maximum value at about 700K. Thermo electric power (TEP) of the sample is negative and the value is about -80 µV/K at RT. The value increases with increasing temperature reaching a maximum value of -140 µV/K at about 600K. The compound exhibits temperature independent power factor in the temperature range 300–550K The calculated figure of merit 1.3 × K-1 is comparable to 7 × 10-4 K-1 of Si-Ge alloys which are used as high temperature thermoelectric materials.

Download Full-text

Electrical Resistance and Thermo-Electric Power of the Alkali Metals

Physical Review ◽

10.1103/physrev.23.357 ◽

1924 ◽

Vol 23 (3) ◽

pp. 357-376 ◽

Cited By ~ 35

Author(s):

Charles C. Bidwell

Keyword(s):

Electric Power ◽

Electrical Resistance ◽

Alkali Metals ◽

Thermo Electric

Download Full-text

PHONON-DRAG EFFECT OF ULTRA-THIN FeSi2 AND MnSi1.7/FeSi2 FILMS

Modern Physics Letters B ◽

10.1142/s0217984911027078 ◽

2011 ◽

Vol 25 (22) ◽

pp. 1829-1838 ◽

Cited By ~ 6

Author(s):

Q. R. HOU ◽

B. F. GU ◽

Y. B. CHEN ◽

Y. J. HE

Keyword(s):

Electrical Resistivity ◽

Seebeck Coefficient ◽

Single Crystals ◽

Thermoelectric Power ◽

Power Factor ◽

Low Temperatures ◽

Room Temperature ◽

Phonon Drag ◽

Drag Effect ◽

Thermoelectric Power Factor

Phonon-drag effect usually occurs in single crystals at very low temperatures (10–200 K). Strong phonon-drag effect is observed in ultra-thin β- FeSi 2 films at around room temperature. The Seebeck coefficient of a 23 nm-thick β- FeSi 2 film can reach -1.375 mV/K at 343 K. However, the thermoelectric power factor of the film is still small, only 0.42×10-3 W/m-K2, due to its large electrical resistivity. When a 27 nm-thick MnSi 1.7 film with low electrical resistivity is grown on it, the thermoelectric power factor of the MnSi 1.7 film can reach 1.5×10-3 W/m-K2 at around room temperature. This value is larger than that of bulk MnSi 1.7 material in the same temperature range.

Download Full-text