The change in the specific resistance of bismuth when subject to a magnetic field is far greater than that of most metals,
e
.
g
., a field of 10 kilo-gauss, at liquid air temperature, increases the resistance of bismuth eightfold, whilst the same field causes an increase of only 0·1% in the resistance of silver. Besides the large change of resistance it is found that the Hall coefficient of bismuth is also much greater than of most metals, and shows a curious dependence upon on the magnetic field strength, as well as a very striking temperature dependence. In this paper these effects are considered on the basis of a theory previously of bismuth, and the properties of the dilute solid solutions of other elements in bismuth.* It was shown that in bismuth the relation between the structure and the available number of valency electrons was such that these electrons formed an almost closed group, or in other words an almost completely filled Brillouin zone. In such a case an electric current is carried by a number (in bismuth a very small number) of electrons, and an equal number of positive holes. By positive holes we mean the few vacant places which are left when a zone or energy band is almost completely filled. These vacancies behave like positive charges; their effective mass is, in general, smaller than that of free electrons.
Galvanomagnetic properties of polycrystalline Bi1-xSbx solid solutions in the concentration range x = 0-0.25
