Semiconduction in non-stoichiometric rare earth oxides
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 LnO1.70-LnO1.83(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 LnO1.5(Ln = Nd or Y). The reflectance spectra of Pr and Tb oxides show a minimum around a composition of LnO1.75.