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We present new experimental results for the transport properties of Ni. In comparing these results to previously published values, we show that there exists a consistent group of experimental data which establishes reliably the transport properties of pure Ni from perhaps 30 to 1500 K. In the paramagnetic range (T > 630 K), these properties show three characteristic features: a positive slope of the thermal conductivity (which is equivalent to an electrical resistivity increasing less than linearly with temperature), a large negative thermopower, and a Lorenz function substantially larger than the Sommerfeld value, L0. In attempting to provide an explanation of these features, we have discovered that the model of Mott, wherein the electronic relaxation time is inversely proportional to the density of states, does not appear to be universally valid and, more importantly, that the observed properties cannot be consistently explained if we assume pure electron–phonon scattering. To achieve consistency, at least one other scattering mechanism has to be included, such as normal electron–electron scattering; this will be taken up in detail in a subsequent publication.

The recent development of ac bridges for precise resistance determinations has brought on the not altogether unexpected discovery of significant differences between dc and ac measurements. In this article, we discuss one such difference, observed in germanium resistance thermometers, and show that it can be unequivocally ascribed to the Peltier effect, the dc measurement in this case being in error. This conclusion is based on a thermal model of the resistor which predicts accurately the magnitude and frequency variation of the observed effect, both for 2- and 4-terminal measurements. The applicability of this model to other devices is briefly discussed.

The thermal conductivity, electrical resistivity, and thermoelectric power of well-characterized, polycrystalline specimens of pure Co have been determined in the temperature range of 90 to 1250 K. Additionally, the measurements of the electrical resistivity have been extended to 1750 K, and the coefficient of thermal expansion measured between 300 and 770 K. The new results are compared with those previously published, and, for the low temperature h.c.p. phase, compared with predictions based on published band structure calculations. Qualitatively, the observed results agree with the predictions, particularly as far as the very unusual temperature variation of the Lorenz function is concerned; quantitative comparisons, however, are impossible, due to the lack of precision in the calculated band structures. The theoretical analysis of the results for the high temperature f.c.c. phase will be given together with that of Ni in Part II.

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