The Thermoelectric Power of Calcium (1X) Aluminum(x), CALCIUM(.60) ALUMINUM(.40Y) Gallium(y), and LANTHANUM(1  Aluminum(x) Metallic Glasses.
Abstract
The thermopower, S, and normalized resistance, R(T)/R(,o), as a function of temperature of some Ca(,1 x)Al(,x), .20 < x < .45, Ca(,.60)Al(,.40y)Ga(,y), y = .10 and .20, and La(,1x)Al(,x), .18 < x < .35 metallic glasses have been measured. It is found that the temperature coefficient of resistivity, (alpha) = (rho)('1)d(rho)/dT, for all the samples is negative and the thermopower is positive for the Ca(,1x)Al(,x) and Ca(,.60)Al(,.40y)Ga(,y) alloys while it is negative for the La(,1x)Al(,x) alloys. The thermopower and resistivity of the Ca(,.55)Al(,.45), Ca(,.60)Al(,.40) and both CaAlGa alloys are anomalously high. The value of 502 (mu)(OMEGA)cm and 32 (eta)V/K('2) for the Ca(,.60)Al(,.20)Ga(,.20) alloy are the largest reported room temperature value of (rho) and S/T, respectively, of any nonmagnetic amorphous alloy. The value of S/T for the Ca(,1x)Al(,x) alloys with x = .30, .33, .40 and .45 increase steadily as the temperature decreases and exhibit a small shoulder like structure at approximately 50 K. Below this temperature S/T increases much more rapidly and reaches a maximum value at very low temperatures. This type of temperature dependence in S/T is also observed in both CaAlGa alloys with the exception that the shoulder like structure is much less pronounced. The value of S/T for the La(,1x)Al(,x) alloys remains relatively constant at high temperatures, ((theta)(,D) < T < 300 K). However, below (theta)(,D), the value of S/T exhibits a smooth and rapid increase as the temperature decreases and reaches a maximum value just before the onset of superconductivity. The observed temperature dependence of the thermopower at low temperatures, (T < (theta)(,D)), may be understood in terms of the electronphonon mass enhancement. Neither the ZimanFaber diffraction model nor the Mott sd scattering model are able to explain the magnitude and compositional dependence of the thermopower and resistivity of these three alloy systems.
 Publication:

Ph.D. Thesis
 Pub Date:
 1984
 Bibcode:
 1984PhDT........66D
 Keywords:

 Physics: Electricity and Magnetism