Semiconduction in non-stoichiometric rare earth oxides

Abstract

The electrical conductivities of the sesquioxides, dioxides and a few non-stoichiometric oxides of Pr and Tb have been measured at various temperatures and the activation energies for the conduction process have been reported. The conductivity passes through a maximum in the composition range LnO_1.70-LnO_1.83(Ln = Pr or Tb). The conductivity data are consistent with the hopping model for these semiconductors. Calculation of the Frohlich's coupling constant and transition probability in Pr₆O₁₁ has shown that the intermediate polaron theory is applicable to these systems. The electrical conductivities of CeO₂+Y₂O₃ and CeO₂+Nd₂O₃ systems show a maximum in conductivity at a composition of about 30 mole % of LnO_1.5(Ln = Nd or Y). The reflectance spectra of Pr and Tb oxides show a minimum around a composition of LnO_1.75.