Authors: Liying Wu Xiaoli Wang Jimmy H Wang Ruyan Guo Amar S Bhalla
Publish Date: 2009/10/01
Volume: 44, Issue: 19, Pages: 5420-5427
Abstract
The 1 − xBaTiO3–xBi3/4Na1/4Mg1/4Ti3/4O3 02 ≤ x ≤ 09 ceramics were prepared by conventional solidstate reaction route Their dielectric properties were found to follow a modified Curie–Weiss law and an empirical Lorenztype relation in respective temperature regions Their dielectric relaxation times fit well with the Vogel–Fulcher relation for x = 02 03 and 04 For x = 05 06 07 and 08 however the fitting curves of Vogel–Fulcher relation showed certain deviation from the experimental data Based on the theoretical treatment of Landau–Ginsburg–Devonshire theory an approximate treatment of the Efield dependence of the permittivity was adopted and found to describe well the field dependence of the permittivity for x = 03 at temperatures equal to and below Tm temperature of maximum dielectric permittivity A combined Langevintype expression used in the present work appears to give a good account for the field dependence of the permittivity assuming polar regions are of a statistical cluster size For polar clusters of linear dimension L ~ 4–8 nm for instance the fitted values of polarization are in the range of P ~ 62–98 μC/cm2This work has been supported by US National Science Foundation under grant number NSF 0833000 and by US Office of Naval Research under grant number N000140810854 One of the authors acknowledges the support of National Natural Science Foundation of China Project 50772087 and scholarship from China Scholar Council through the program of National studyabroad project for postgraduates of high level universities
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