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Unusual thermoelectric behavior of packed crystalline granular metals

M. Ausloos·M. Pekala·J. Latuch·J. Mucha·Ph. Vanderbemden·B. Vertruyen·R. Cloots
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Abstract

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 300K. 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 dependences, e.g. $\simeq$ $T^{-3/4}$ at low $T$, while (iii) the thermoelectric power (TEP) is positive, (iv) shows a bump near 60K, 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.

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M. Ausloos, M. Pekala, J. Latuch, J. Mucha, Ph. Vanderbemden, B. Vertruyen, R. Cloots. 2004-12-13. Unusual thermoelectric behavior of packed crystalline granular metals. https://doi.org/10.1063/1.1808248

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