High frequency dielectric relaxation in lanthanum modified PbTiO3 ferroelectric ceramics

Abstract

Dielectric measurements of lanthanum modified lead titanate ceramics were carried out in a frequency and temperature range of 70 × 10 6 Hz -2 × 10 9 Hz and 300 K -420 K, respectively. Dielectric relaxation appears around 7 × 10 8 Hz at room temperature, and the maximum of the dielectric relaxation was around 393 K, the transition temperature (T c ). The relaxation frequency passes through a minimum at T c 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.

A Note on the Guerra and Talagrand Theorems for Mean Field Spin Glasses: The Simple Case of Spherical Models

“…In fact it is well known that (5) can also be written in the form [17,18,19] (and for a recent review see also [20]):…”