The electrical resistivity of the two phases of sodium at low temperatures

Abstract

At low temperatures the crystal structure of sodium changes by the martensitic mechanism from body-centred cubic to close-packed hexagonal. By measurements on specimens which partially transform on cooling and by measurements on specimens whose composition has been changed by suitable straining, the resistivity of the two phases has been approximately determined between 15 and 50 °K. The hexagonal close-packed phase has a lower ideal resistivity than that of the body-centred cubic phase (by about 40% at 20 °K), whereas the residual resistivity is effectively independent of the structure. Some theoretical implications are discussed.