INFLUENCE OF THE Zr4+/Ti4+ RATIO ON THE PROPERTIES OF THE 0.98Pb(Zr1-xTix)O3-0.02La(Fe0.53+, Nb0.55+)O3 COMPOSITIONS

In this paper, some compositions belonging to the 0.98Pb(Zr1-xTix)O-3 - 0.02La(Fe-0.5(3+), Nb-0.5(5+))O-3 system have been investigated. The considered materials have been obtained by solid state reaction technique at high temperatures (1100 degrees C, 1150 degrees C, 1200 degrees C and 1250 degrees C). Three values of x (one in tetragonal region, one in Morphotropic Phase Boundary-MPB- region and one in rhombohedral region) have been chosen for the study in the range of 0.42 - 0.58. Sintering behaviour of the ferroelectric compositions has been studed by the experimental determination of the density by the method Archimedes. These ferroelectric compositions have been investigated in terms of their structural behaviour using X-ray diffraction (XRD) analysis. The XRD results have evidenced the formation of the perovskite type structure for all the studied compositions. The influence of the Zr4+/Ti4+ ratio correlated to the sintering temperature on the degree of incorporation of the elements in the solid solution have been studied too. All the considered ferroelectric compositions have been characterized by a high anisotropy. The PZT modified compositions reveal that the piezoelectric properties are governed by the Zr4+/Ti4+ ratio and the sintering temperature too. For the electromechanical coupling factor (k(p)) the maximum value k(p) = 0.67 has been obtained for the composition with x = 0.58 and sintered at 1200 degrees C.