Dresden 2003 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 7: Poster

DF 7.25: Poster

Mittwoch, 26. März 2003, 14:30–18:00, P2a

Dielectric dispersion and distribution of the relaxations times of the relaxor 0.4PSN-0.3PMN-0.3PZN ceramics — •Juras Banys¹, Jan Macutkevic¹, Algirdas Brilingas¹, Karlis Bormanis², Andris Sternberg², and Vismant Zauls² — ¹Faculty of Physics, Vilnius University, Sauletekio 9, 2040 Vilnius, Lithuania — ²Institute of Solid state Physics, University of Latvia,8 Kengaraga str., 1063 Riga , Latvia

In this contribution the dielectric spectra of new relaxor ceramics 0.4PSN-0.3PMN-0.3PZN is presented. Measurements have been performed in the frequency range 20 Hz to 2GHz. On cooling the dispersion and loss spectra strongly broaden and slow down, but remain symmetric so that the Cole-Cole model is applicable. This enabled us to determine also the width of the uniform distribution function of the relaxation times and its temperature dependence above room temperature. The longest and mean relaxation times diverge according to the Vogel-Fulcher law with the same freezing temperature T = 210 K. The shortest relaxation time is about ps and remains almost temperature independent. The quantitative estimates indicate a strongly anharmonic potential for polarization fluctuations which are restricted to inter-cluster boundaries. We can conclude, that the extraction of continuous relaxation times distribution of the Debye fundamental processes directly from the broadband dielectric spectra allows better understanding dynamic phenomena in solid state.