STRUCTURE-PROPERTY CORRELATION OF xPb(Ni_(0.33Nb_(0.67)O_3-(1-x)Pb(Zr_(0.31)Ti_(0.69)O_3 BASED RELAXOR-FERROELECTRIC CERAMICS SYNTHESIZED VIA COLUMBITE PRECURSOR METHOD

摘要

The PNN-PZT xPb(Ni_(0.33Nb_(0.67)O_3-(1-x)Pb(Zr_(0.31)Ti_(0.69)O_3 (0.2≤x≤0.6) based relaxor-ferroelectric material was synthesized by columbite precursor (NiNb_2O_6) method via conventional solid state reaction. Homogeneous mixture of required oxides and precursor was calcined at 850°C for 4 hrs to obtain phase pure perovskite. Pellets of PNN-PZT ceramics were sintered at 1100°C for 4 hrs. Phase pure perovskite structure was confirmed by the X-ray diffraction analysis. From the X-ray diffraction analysis it is also confirmed that there is a structural transformation from the rhombohedral to tetragonal with increase in PZT content and existence of morphotrophic phase boundary (MPB) at x = 0.5 composition. The morphology and microstructure of the sintered pellets were observed using the scanning electron microscope. P-E loop measurement shows the high remnant polarization (19.12 μC/cm~2) and low coercive field (6.89 kV/cm) at MPB compared to all other compositions. The electromechanical planar coupling coefficient (k_p) was measured through the resonance and anti-resonance method using the LCR meter. The piezoelectric strain coefficient (d_(3)) measured directly using the d33-meter. At x = 0.5 composition the highest value of d_(33)= 398 pC/N is obtained.