Electrical conductivity in polymeric sulphur nitride at high pressures

Abstract

The resistivity along the chain axis in polymeric sulphur nitride has been followed under pressure using a variety of hydrostatic and quasi hydrostatic techniques. The large increase in conductivity with pressure at room temperature previously reported up to 9 kbar is confirmed, and is seen to level off above 30 kbar at a conductivity ratio sigma (p)/ sigma (0) approximately 10. The T2 dependence of the resistivity seen at atmospheric pressure, associated with electron-electron scattering has been followed with pressure. At moderate pressures this dependence is more complicated; there are two regimes with different T2 coefficients which both saturate below room temperature, pointing to a semimetallic band structure with small pockets of electrons and holes present. The high-pressure limit of sigma (p)/ sigma (0) is seen to correspond to the level of electron-phonon scattering that can be expected from the superconductivity data.