The electrical conductivity of the transition metals.

Abstract

1·1. The conductivity of a pure metal depends upon a large number of quantities, and it is difficult to decide the relative importance of the various constants since they often produce compensating effects. It is, however, generally agreed that the low conductivity of the divalent metals, and especially of bismuth, is due to the small effective number of conduction electrons. It has further been suggested by Mott (1935, 1936 a , 1936 b ) that the low conductivity of the transition elements, which are even worse conductors than the divalent elements, is due to another cause, namely, to the abnormal smallness of the free path. The transition metals possess conduction electrons in an s -band and they also have unfilled d -bands. Hence, in addition to the normal s-s transitions the electrons can also undergo s-d transitions, and this results in a shortening of the free path. One of the difficulties in the way of a complete theory is the necessity of separating the normal s-s transitions from the s-d transitions, and so far it has not proved possible to do this. In the present paper it is shown that the resistances produced by the two different types of transition have different temperature variations, and therefore that it should be possible to estimate their relative importance by measurements over a sufficiently large range of temperature.