Dielectric Dispersion in Pure PMN and PMN with 10% PT Single Crystals

ISSN： 0015-0193

Source： Ferroelectrics, Vol.339, Iss.1, 2006-01, pp. : 21-28

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

Dielectric permittivity of PMN and PMN with 10% PT single crystals was measured in the frequency range from 20 Hz to 3 GHz. Dielectric dispersion was observed in all investigated frequency range. From the frequency dependence of the real and imaginary parts of dielectric permittvity, the distribution of relaxation times was calculated. The low frequency limit of the distribution of the relaxation times diverges according to the Vogel–Fulcher law with the freezing temperature T f = 228 K for PMN, which is in good agreement with the mean relaxation time temperature dependence obtained from Cole–Cole, equation and T f = 282 K for 0.9 PMN–0.1 PT, which is higher than obtained from Cole–Cole equation. Broadening of the relaxation time distribution function at low temperatures clearly indicates the existence of at least two different components making contribution to the total dielectric spectrum of PMN. One of the components can be attributed to polar nano regions, whose dynamics slows down and freezes at T f , and the another component is the paraelectric matrix, which stays stable even at low temperatures.