[en] thermoelectric power ; granular metals ; electrical resistivity
[en] Loosely packed granular materials are intensively studied nowadays. Electrical and thermal transport properties should reflect the granular structure, as well as intrinsic properties. We have compacted crystalline CaAl-based metallic grains and studied the electrical resistivity and the thermoelectric power as a function of temperature (T) from 15 to 300 K. Both properties show three regimes as a function of temperature. It should be pointed out: (i) The electrical resistivity continuously decreases between 15 and 235 K, (ii) with various dependencies, e.g., similar ~ T(-3/4) at low T, while (iii) the thermoelectric power (TEP) is positive, (iv) shows a bump near 60 K, and (v) presents a rather unusual square root of temperature dependence at low temperature. It is argued that these three regimes indicate a competition between geometric and thermal processes-for which a theory seems to be missing in the case of TEP. The microchemical analysis results are also reported, indicating a complex microstructure inherent to the phase diagram peritectic intricacies of this binary alloy. (C) 2004 American Institute of Physics.
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The following article appeared in J. Appl. Phys. 96, 7338 (2004) and may be found at http://link.aip.org/link/?JAPIAU/96/7338/1.