|08-140||Catarine Padovani Moreira||Garcia, D.(Universidade Federal de São Carlos); Miranda, M.M.(Federal University of São Carlos); Milton, F.P.(Universidade Federal de São Carlos); Moreira, C.P.(Federal University of São Carlos); Estrada, F.R.(Brazilian Center for Research in Energy and Materials);||
The aim of this work was to determine phase transformations as also the polar state changes of morphotropic phase boundary compositions of the (Pb1-xCax)TiO3 solid solutions. Ceramic bodies in the concentration x= 0.40 were prepared by solid state reaction under adequate conditions to obtain dense and crack-free microstructure. Considering the experimental data of the electromechanical resonance of (Pb0.60Ca0.40)TiO3 poled ceramics, changes of the piezoelectric coefficients were evaluated in the temperature interval from cryogenic up to 600K. The discussion was based on the data from experimental characterization and from a finite element analysis of the material elastic, dielectric and piezoelectric coefficients. From these results at least four anomalies were observed in the temperature dependence of the piezoelectric parameters, which could be related to structural transformations, effects of ferroelectric domain pinning and/or incommensurable phase transitions for these particularly compositions.