Dresden 2006 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 3: Poster Session

DF 3.27: Poster

Montag, 27. März 2006, 09:30–17:00, P1

Dielectric spectra of PMN-PSN-PZN ceramics — •Juras Banys¹, Jan Macutkevic¹, Algirdas Brilingas¹, Jonas Grigas¹, Andris Sternberg², Vismants Zauls², and Karlis Bormanis² — ¹Department of Radiophysics, Faculty of Physics, Vilnius University, Lithuania — ²Institute of Solid State Physics University of Latvia, Latvia

The dielectric dispersion of various ceramics PbSc_1/2Nb_1/2O₃-PbZn_1/3Nb_2/3O₃-PbMg_1/3Nb_2/3O₃ (PSN-PMN-PZN) was measured in very wide frequency range and analyzed in terms of distributions of relaxations times, using Tichonov regularization method. Symmetric and narrow distribution of relaxation times is obtained at higher temperature. On cooling the distribution function becomes asymmetrically shaped and second maximum appears. The longest relaxation times diverge according to Vogel-Fulcher law, however the most probable relaxation time diverges according to Arrhenius law. Enough high activation energy (0.5-0.2 eV) of most probable relaxation times show that in both parts of distribution of relaxation times dominate strongly correlated relaxation. The freezing of dynamics of polar nano regions in PMN-PSN-PZN ceramics must understood as uninterrupted process on cooling from T$_0$ to 0 K. Only at very low temperatures (T<50 K) the contribution of polar nano region becomes enough small, so that the contribution of non-polar matrix can be clearly resolved. The obtained activation energy of fluctuations in non-polar matrix is much smaller as activation energy of most probable relaxation times.