UNCONVENTIONAL METHODS FOR INFLUENCING FLUID FLOW. PART VI. THE EFFECT OF A TRANSVERSE MAGNETIC FIELD ON THE THERMOELECTRIC PROPERTIES OF POLYCRYSTALLINE BISMUTH-ANTIMONY ALLOYS.
Abstract
The effect of a transverse magnetic field on the thermoelectric properties (Seebeck coefficient, thermal conductivity, electrical resistivity and figure of merit) of n-type polycrystals of bismuth-antimony alloys containing 0, 5, 12 and 19 atomic per cent antimony in bismuth have been investigated at 90K and 310K. Pure bismuth has the largest zero field Seebeck coefficient as well as figure of merit of all the samples tested at both 90K (-57 microvolts/ K and 0.00043/K) and 310K (-66 microvolts/K and 0.00034/K). The magnetoresistivity of the pure bismuth sample at 90K is extremely large, (7.5 times its zero field value at 4.1 kilogauss); it is believed due mainly to its special band structure (overlapped energy bands) which is one of the characteristics of semimetals. As a result of its extremely large magnetoresistivity, the figure of merit decreases with field at fields larger than a few hundred gauss. The zero field figure of merit of Bi95Sb5 at 310K is just slightly smaller than pure bismuth's (0.0003/K vs 0.00034/K) but its relative change is much larger so that its figure of merit overtakes pure bismuth's at a field of 4 kilogauss. The figure of merit of Bi88Sb12 under the presence of a magnetic field is very promising. It reached a value of about 0.0004/K at 4.1 kilogauss. The performance of Bi81Sb19 both at 310K and 90K, with and without a magnetic field, was very disappointing. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1966
- Accession Number
- AD0636257
Entities
People
- Henry N. Chuang
Organizations
- Carnegie Institute of Technology