Evolution of hysteresis loops with temperature studied on dielectric cermaics basedon tetragonal tungsten bronze structure

摘要

We report on dielecrtic and ferroelectric properties of type I ceramics initially composed of a tetragonal tungsten bronze phase (K_0.2Sr_0.4NbO_3) mixed with a perovsktie phase (Pb(Mg_1/3Nb_2/3)O_3/PbFe_1/2Nb_1/2)O_3), and sintered in an oxygen flow in the presence of a lithium salt. Compositions presented here cover all this relaxor/TTB diagram. Most of them lead to ceramics characteried by a type I behavior. We shall show up the evolution of the dielectric constant versus the percent w Li_2CO_3 at various temperatures and correlate those results with hysteresis loops shapes. Morecover the study of hysteresis loops at various temperatures will allow us to determine the ferroelectric behavior of those dielectric materials.