Nonequivalent-F-induced relaxations in LaF3 single crystals over a broad temperature range

摘要

The dielectric properties of LaF3 single crystals were investigated in the temperature range from 110 to 773 K and the frequency range from 100 Hz to 10 MHz. Two thermally activated relaxations (R1 and R2) and a dielectric anomaly (A) were observed. The lower temperature relaxation (R1) was ascribed to a polaronic relaxations due to fluorine ions diffusion within the F-1 sublattice and fluorine ions hopping in F-1 sublattice. The higher temperature relaxation (R2) is Maxwell-Wagner relaxation due to the blocking of electrodes associated with the ionic exchange between F-1 and F-2,F-3 sublattices and among the three nonequivalent sublattices. The anomaly appearing in the highest temperature range is related to the inductive effect arising from the coupled electron-ionic inductive response.