Mixed ionic-electronic conductivity in phases in the praseodymium oxide system

The praseodymium oxide system contains a series of related phases with very narrow compositional width and unique extended defect structures, rather than the more common isolated point defects. The electrical conductivity of three of these phases has been measured by the use of AC complex impedance and DC methods in the temperature range 75-400 degreesC. The beta phase, Pr6O11, exhibits a total conductivity of 6.77 x 10(-2) S/cm at 400 degreesC, with an activation energy of 0.52 eV/atom. The conductivity of the epsilon phase, Pr5O9, is slightly lower, with an activation energy of 0.51 eV/atom. The iota phase, Pr7O12, has a very low conductivity. The activation energies for electrical transport in the beta and epsilon phases are in the general range found in a number of mixed conductors based upon LSGM oxides.