TETRAGONAL AND RHOMBOHEDRAL PHASE COEXISTENCE IN THE SYSTEM - PBZRO3-PBTIO3-PB(FE-1 5,NI-1/5,SB-3/5)O-3/

Various compositions of xPbZrO(3)-yPbTiO(3)-zPb(Fe-1/5, Ni-1/5, Sb-3/5 )O-3 piezoelectric ceramics, having a Zr/Ti ratio between 45.1/49.9 an d 51.1/43.9, were prepared using the usual ceramics technique, in the temperature range 850-1200 degrees C. The electromechanical coupling f actor (k(p)), piezoelectric constant (d(ij)) and Young's modulus (Y) a re measured as a function of the Zr/Ti ratio. The obtained results are discussed on the basis of the effects of varying the Zr/Ti ratio. The effects of sintering temperature on microstructure are studied by mea ns of a scanning electron microscope (SEM). Grain growth is enhanced b y increasing temperature. X-ray diffraction demonstrated the co-existe nce of both tetragonal and rhombohedral phases. The lattice parameter measurements showed that tetragonal and rhombohedral unit cells of the two phases depend on the sintering temperature.