| Five PSN-PMN-PT-PZ components with morphotropic phase boundary (MPB) were designed based on ternary system PSN-PMN-PT and PMN-PT-PZ at MPB and the rule of the linear combination.Relaxor ferroelectric single crystals xPSN-yPMN-zPT-hPZ (x/y/z/h= 6/60.5/33/0.5 6/60/33/1,5/58/34/3,5/55/35/5,5/53/35/7) with large-size and cube shape was obtained by high temperature flux method. A pure perovskite structure without any pyrochlore phase was suggested by XRD. Microtopography, growth mechanism and electrical properties of the crystals were investigated and characterized.The exposed surfaces of 0.05PSN-0.55PMN-0.35PT-0.05PZ with cube geometry shapes are (001). Scanning electron microscope (SEM) reveals a layered structure, and the bridging growth mechanism is proposed. The 0.05PSN-0.55PMN-0.35PT-0.05PZ single crystal shows a large coercive electric field (Ec～3.52 kV/cm), high phase-transition temperature (Tr-t～104℃,Tc～149.5℃), excellent piezoelectric and ferroelectric properties(d33～1080pC/N, Pr～25.4μC/cm2). With frequency increasing, the diffuse phase transition decreases.xPSN-yPMN-zPT-hPZ (x/y/z/h= 6/60/33/1,5/58/34/3,5/55/35/5,5/53/35/7) quaternary ferroelectric ceramics with morphotropic phase boundary (MPB) were prepared by two-step synthesis method. The influences of PZ additives on microtopography and properties of ceramics were investigated. Experimental results show that all ceramics possess a pure perovskite structure. With the increase of PZ content, the Curie temperature Tc and dielectric diffuseness of PSN-PMN-PT-PZ quaternary ceramics increase, while the dielectric constant decreases. The optimal properties are achieved in 0.05PSN-0.55PMN-0.35PT-0.05PZ:Curie temperature Tc= 151 ℃; piezoelectric coefficient d33=325pC/N; planar electromechanical coupling kp=54.34%; dielectric permittivity smax=7779; dielectric loss tanδ=0.02, respectively. |
PDF Full Text Request