Synthèse, caractérisations et étude structural des céramiques PZT de type pérovskite Pb1-xLazCax [(ZrY Ti1-Y)0.75 (Sb) 0.25]O3

Abstract

Conclusion Générale 98 Abstract: At this stage of o ur study on the ternary system: Pb 1 - x La z Ca x [(Zr y Ti 1 - y ) 0,75 (Sb) 0,25 ]O 3 . It seems necessary to draw some conclusions and confirm certain assumptions we have made progress. Interest presented by the piezoelectric ceramic PZT type led us to synthesize new materials . First, we studied the morphology of PZT ceramics of the solid solution of lead zirconate titanate, using a differential scanning calorimetry ( DSC ) and differential thermal analysis ( DTA ). We determined the mechanism forming reaction of the solid solution in the presence of PZT base oxides PbO, Z rO 2 , TiO 2 and doping oxides La 2 O 3 , CaCO 3 and Sb 2 O 3 . The mechanism is follow ing : 3 PbO Pb3O4 (1) Pb 3 O 4 3 PbO + O 2 (2) PbO + TiO 2 PbTiO 3 (3) PbTiO 3 + ZrO 3 PZT (4) The temperature of formation of lead zirconate titanate ( PZT ) is about 700 ° C . This is associated with the diffusion of Zr +4 and Pb +2 in the structure of perovskite lead titanate u p to saturation. Subsequently, the sample sintered at a temperature of 1180 ° C has a density close to theoretical de nsity. We as note, as the addition of the doping agents increases the density for the unit of the doped samples of 1% up to 5% , this thickening is characterized by a reduction in porosity. What means that the volume of the mesh decreases, the structure becomes compact. By the method of analysis of diffraction of X - ray, we determined the border mor pho - tropic of phase (Tétragonal + Rhomboédral ) in piezoelectric ceramics of type PZT in the presence of the oxides La 2 O 3 , CaCO 3 and Sb 2 O 3 . The effect of the doping agents on the density and the porosity of solid solution PZT - LCS were studied. It was noted that the shape of the curve of porosity is the reverse of that of the density, the packing implies a reduction in the number and dimensions of the pores, therefore the volume of the mesh decreases and consequently the structure becomes more compact. Lastly, we characterized these new piezoelectric materials by their physical properties such as the temperature of Curie, permittivity, the loss angle and the resistivity according to the various temperatures of sintering and freque