Low temperature dielectric studies of some rare-earth oxides

Abstract

The variation of the dielectric constant ( epsilon ') and the dielectric loss ( epsilon ") of CeO₂, Pr₆O₁₁, Tb₄O₇ and RE₂O₃ (where RE=Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb) are studied at 1.542 kHz in the temperature range 4.2-300K. A peak in epsilon " around 216K for CeO₂ and 84K for Pr₆O₁₁ is observed and identified as being due to dipoles produced by defects. An unusual peak in epsilon ' around 42K is observed for Sm₂O₃. All other sesquioxides (with the exception of Tb₂O₃) behave as low-loss ionic solids showing a systematic increase in both omega ' and epsilon " with temperature. Tb₂O₃ and Tb₄O₇ become exceptionally lossy above 150K and both epsilon ' and epsilon " increase rapidly above this temperature.