Study on dielectric properties of PMN-PZN-PT ferroelectric relaxor ceramics

The influence of additions and processing on the microstructure and properties of PMN-PZN-PT ceramics was studied. Experimental results showed that the DC bias character of PMN-based ceramics doped with PZN could be improved; proper excess MgO is advantageous to inhibiting the pyrochlore phase and increasing the dielectric constant. Dielectric loss could be decreased by adding MnO₂. It was also found that air quenching and annealing under proper temperature can improve the microstructure and dielectric properties, particularly in increasing the voltage breakdown strength. The reasons for this are that uniform distributions of composition in grains and in grain boundaries and a lower order degree of Mg/Nb=1:1 in micro regions could be obtained by air quenching and annealing. The results indicated that the pyrochlore phase could be eliminated and perovskite structure could be stabilized effectively. The microstructure and breakdown mechanism were analyzed by means of XRD (X-ray diffraction), SEM (scanning electron microscopy), and STEM. Ferroelectric relaxor ceramics with high performance at low sintering temperature (900°C) were fabricated