On-line version ISSN 1980-5373
GUERRA, José de los Santos and EIRAS, José Antonio. High frequency dielectric relaxation in lanthanum modified PbTiO3 ferroelectric ceramics. Mat. Res. [online]. 2004, vol.7, n.2, pp. 325-328. ISSN 1980-5373. http://dx.doi.org/10.1590/S1516-14392004000200017.
Dielectric measurements of lanthanum modified lead titanate ceramics were carried out in a frequency and temperature range of 70 ´ 106Hz - 2 ´ 109Hz and 300 K - 420 K, respectively. Dielectric relaxation appears around 7 ´ 108Hz at room temperature, and the maximum of the dielectric relaxation was around 393 K, the transition temperature (Tc). The relaxation frequency passes through a minimum at Tc and the dielectric relaxation exists in both paraelectric and ferroelectric phases. A fitting of the experimental data with the Debye relations gives some keys for understanding the dielectric behavior of such materials.
Keywords : dielectric relaxation; ferroelectric ceramics; microwave dispersion.