Effect of Ba(Zn1/3Nb2/3)O3 modification on structure and ferroelectric properties of 0.6Pb(Mg1/3Nb2/3)O3-0.4Pb(Zr0.52Ti0.48)O3 ceramics

In this study, (1−x)[0.6Pb(Mg1/3Nb2/3)O3-0.4Pb(Zr0.52Ti0.48)O3]-xBa(Zn1/3Nb2/3)O3; (1−x)PMNZT60/40-xBZN having x=0, 2.5, 5, 7.5, and 10 mol% ceramics were prepared by mixed oxide powder method and sintered using a two-step process. Phase transitions were investigated by XRD, microstructure by SEM, crystal morphology by TEM, the dielectric and ferroelectric properties by capacitance measurement setup and modified Sawyer-Tower circuit, respectively. The dielectric constant and dielectric loss tangent were measured as functions of both temperature and frequency. The XRD results show the phase transition from tetragonal phase to pseudo-cubic phase with addition of BZN in PMNZT system. Grain size of about 1.23-2.42 μm and crystallite size in a range of 421-2152 nm were obtained. The pure-phase 0.6PMN-0.4PZT ceramics show the normal ferroelectric behavior. The 0.95(PMNZT60/40)-0.05BZN and 0.925(PMNZT60/40)-0.075BZN showed a broad and diffused dielectric properties and the dispersive phase transition, indicating the relaxor ferroelectric behavior. The transition temperature in the BZN-modified PMNZT system is seen to decrease from 166 °C in pure PMNZT60/40 to 102 °C and 54 °C with increasing BZN content to 5 and 10 mol%, respectively. In addition, the maximum dielectric constant is decreased with increasing BZN content. The P-E hysteresis loop measurements show the change from the normal ferroelectric behavior in PMNZT60/40 ceramic to more relaxor behavior that was induced with BZN addition. These results clearly demonstrated the significance of BZN to the electrical responses of the PMNZT60/40 system.