Dielectric relaxation and electrical properties of 0.94Pb(Fe_(1/2)Nb_(1/2))O_3-0.06PbTiO_3 single crystals

摘要

Dielectric response and electrical conduction properties of 0.94Pb(Fe_(1/2)Nb_(1/2))O_3-0.06PbTiO_3 single crystals grown by the Bridgman method were studied. It was found that the single crystals did not show any sign of the presence of Curie temperature between room temperature and 300 ℃. However, they exhibited very high dielectric constant at a frequency lower than 100 kHz, in the order of 10~5. Relaxation occurred at higher frequencies with a large decrease in dielectric constant, to about 1500. The thermal activation energy for relaxation was found to be ～0.17 eV, which is quite close to that for ac conductivity. It followed that the relaxation was attributed to the carriers hopping conduction, which is related to the possible jump motion of additional 3d electron between the equivalent positions of Fe ions.