Impedance spectroscopy study of the electrical conductivity and dielectric constant of polycrystalline LiNbO3

The electrical properties of LiNbO3 ceramic pellets were investigated by impedance spectroscopy in the temperature range of 450-800 degrees C. Impedance data are presented in the Nyquist plot which, in addition to the separation of grain and grain boundary contributions, allows the determination of the relaxation frequency of samples. The results of bulk electrical conductivity and its activation energy, confirmed by measuring samples with different geometrical parameters, are presented. Relaxation frequencies follow an Arrhenius behavior with the same activation energy found for the electrical conductivity. Relaxation frequencies were also used to calculate bulk dielectric constants and the results are compared to the behavior of the real part of the sample dielectric constant. (C) 1999 American Institute of Physics. [S0021-8979(99)01516-9].