Piezoelectric ceramics have excellent piezoelectric,dielectric and ferroelectric properties,and have been widely used in actuators,multilayer capacitors,sensors and transducers.In order to further meet the demand for high piezoelectric performance of high-power devices,in recent years,lead-based relaxation ferroelectric ceramic materials have been extensively studied.Among them,the perovskite structure Pb(Nb,Ni)O3-Pb(Hf,Ti)O3(PNN-PHT)ternary piezoelectric ceramics have excellent piezoelectric properties and are expected to become a high-performance piezoelectric ceramic material.In this paper,the PNN-PHT ternary piezoelectric ceramic material is used as the research object,through the modification of ion doping and composition adjustment,the corresponding adjustment mechanism is discussed.The main contents and conclusions are as follows:A two-step solid-phase reaction method was used to prepare 0.49Pb(Ni1/3Nb2/3)O3-0.51Pb(Hf0.3Ti0.7)O3 ceramics with Li2CO3 and Al2O3.The Li+and Al3+ion pair 0.49Pb(Ni1/3Nb2/3)O3-0.51Pb(Hf0.3Ti0.7)O3 ceramic microstructure,piezoelectric and dielectric properties.The results show that the Li+-Al3+ion pair can construct defective dipoles in PNN-PHT and obtain greater piezoelectric response.The study found that when 0.4 at%Li+-Al3+was used as doping,PNN-PHT ceramics obtained the best electrical properties:d33=1040p C/N,εr=6800,kp=0.59,Qm=60,tanδ=0.023 and Tc=130°C.The effect of PNN component content and dopant Sm2O3 on the microstructure,piezoelectric and dielectric properties of y Pb(Ni1/3Nb2/3)O3-(1-y)Pb(Hf0.3Ti0.7)O3 piezoelectric ceramics was systematically studied.The results show that the rare earth element Sm successfully constructs heterostructure regions in PNN-PHT,which causes the improvement of piezoelectric performance.The optimal doping concentration of Sm2O3 increases with the increase of PNN content.The electrical performance test results show that in the 0.51PNN-0.49PHT component system,when the Sm2O3 doping content is 0.45 at%,the performance of PNN-PHT ceramics is d33=1150p C/N,εr=9800,kp=0.59,Qm=60,tanδ=0.078 and Tc=105°C.A two-step solid-phase reaction method was used to prepare Sb2O3-doped0.49Pb(Ni1/3Nb2/3)O3-0.51Pb(Hf0.3Ti0.7)O3 and 0.49Pb(Ni1/3Nb2/3)O3-0.51Pb(Hf0.4Ti0.6)O3 ceramics.The results show that Sb5+replaces the B-site ions in the PNN-PHT crystal.When the Hf/Ti ratio is 3/7 and the Sb2O3 doping content is 0.25 at%,the performance of the PNN-PHT ceramic is d33=1100p C/N,εr=6120,kp=0.60,Qm=51,tanδ=0.023 and Tc=130°C,when Hf/Ti ratio is 4/6 and Sb2O3 doping content is 0.25 at%,the performance of PNN-PHT ceramic is d33=1010p C/N,εr=5820,kp=0.61,Qm=58,tanδ=0.021 and Tc=135°C.Studies have shown that the higher the Hf/Ti ratio,the greater the solid solubility of Sb2O3,and when the doping concentration is near the solid solubility,the piezoelectric properties of PNN-PHT ceramics are better. |