Electrical conductivity of polycrystalline alkali nitrates in stable states and at phase transitions

The temperature dependence of the electrical conductivity of polycrystalline alkali nitrates between room temperature and their melting temperatures has been studied. The lg =f(1/T) dependence is a discontinuous line consisting of regions of impurity and intrinsic conductivity. The conductivity changes discontinuously at a first-order phase transition, during the transition from a structure with lower symmetry to one with higher symmetry, and vice versa. The activation energy for ionic migration in the series of alkali nitrates is at a minimum for potassium nitrate.