Metal-insulator phase transition and electrical switching in manganese dioxide

A complex investigation of the ac and dc electrical conductivities of the β phase of manganese dioxide has been performed in relation to its atomic structure. The change of conductivity mechanisms depending on temperature in a range of 450–25 K has been shown and the metal-insulator phase transition at low (<90 K) temperatures has been described. The specific feature of this transition by the Mott mechanism is that the metal phase exists at low temperatures, while at higher temperatures, the material manifests semiconductor properties. The low-temperature switching effect with a negative differential conductivity and an N-like current-voltage characteristic associated with the phase transition in manganese dioxide has been found.