Radio and Microwave Spectroscopy of 0.2PMN-0.4PSN-0.4PZN Relaxor Ceramics

Dielectric spectroscopy results of 0.2PbMg _1/3 Nb _2/3 O ₃ -0.4PbSc _1/2 Nb _1/2 O ₃ -0.4PbZn _1/3 Nb _2/3 O ₃ ceramics are reported for 200 < T < 450 K and 20 Hz < v < 11 GHz. Dielectric constant is very high (more than 12000) in the vicinity of the peak. Anomalous broad dielectric relaxation has been observed near and below the temperature of the maximum permittivity, T _m (at 1 kHz). The distribution of relaxation times have been calculated directly from the dielectric spectra. At higher temperatures than the maximum permittivity, T _m the distribution of the relaxation times is symmetrically shaped (Cole-Cole function satisfactory describes the dielectric response). At lower temperatures, the distribution of relaxation times becomes asymmetrically shaped. On further cooling the second maximum appears.

Keywords:

• Ceramics
• relaxors
• dielectric dispersion
• distribution of relaxation times

PACS:

• 77.84.Dy
• 77.80.Bh
• 77.22.Gm

Acknowledgments

This work was supported by the “POLECER” project.