| Multi-layer ceramic electrode co-firing technology is widely used in multilayer ceramic brakes and transformers.In actual production,the sintering temperature of high-performance lead-containing piezoelectric ceramics is generally higher than 1200℃.Electrodes with higher palladium content are often used for multi-layer ceramic co-firing,which greatly increases production costs.Therefore,it is very important to explore the low-temperature co-firing process of lead-containing piezoelectric ceramics.Among many lead-containing piezoelectric ceramics,Pb(Sc1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3(PSN-PMN-PT)ceramics are favored because of their high piezoelectric properties,dielectric properties and electromechanical properties.This paper focuses on 15PSN-51PMN-34PT ceramics,and realizes the low-temperature co-firing technology of PSN-PMN-PT ceramics through CuO doping and the composite of ZnO.(1)A two-step synthesis method was used to prepare PSN-PMN-PT+xwt%CuO(x=0,0.125,0.25,0.3,0.4)ternary piezoelectric ceramics.The addition of CuO achieved sintered dense ceramics at 950℃ with a relative density of 99.1%.The XRD analysis of the doped ceramics as pure perovskite structure shows that CuO was successffully incorporated into the matrix ceramics.Through the investigation of the electrical properties of ceramics,it is found that CuO can increase the phase transition temperature Tr-t and Tc of ceramics.PSN-PMN-PT+0.125wt%CuO ceramic obtained the most excellent comprehensive performance:Tr-t=120 ℃,Tc=185 ℃,d33=518 pC/N,d33*=853 pm/V,pr=27.8 μC/cm2,Ec=6.8 kV/cm.In addition,ceramics also exhibit a wide pyroelectric current peak,indicating that the current temperature stability is excellent.These results indicate that CuO-doped PSN-PMN-PT ceramic is expected to be a candidate material for multilayer ceramic brakes and pyroelectric infrared detectors.(2)This chapter successfully prepared yZnO:PSN-PMN-PT(y=0,0.03,0.05,0.1,0.2,0.3mol)composite ceramics by solid-phase sintering.The composite ceramic has achieved sintered dense ceramics at 1150℃.According to scanning electron microscope test found that small sub-micron particles were embedded in the grain boundaries of the micron-sized grains,indicating that the ceramic structure is a 0-3 composite structure.Through XRD test,it is found that the ceramic contains two sets of diffraction peaks of perovskite and ZnO.The results of EDS spectroscopy further prove that the ZnO:PSN-PMN-PT composite ceramics have been successfully prepared.Through the test of the dielectric temperature spectrum,it is found that the addition of ZnO leads to a decrease in the phase transition temperature Tr-t and an increase in the Curie temperature Tc.According to the research on the electrical properties of composite ceramics,it is found that the addition of ZnO can improve the piezoelectric properties of the ceramic.When y=0.05mol,the ceramic obtains the best comprehensive performance:Tr-t=85℃,Tc=195℃,d33=620 pC/N,d33*=585 pm/V,Pr=33.15 μC/cm2,Ec=6.2 kV/cm.The composite ceramics of all components exhibit excellent temperature stability,and can still maintain 80%of the piezoelectric performance when annealed at 180℃.(3)The zZnO:15PSN-51PMN-34PT+0.125wt%CuO(z=0,0.03,0.05,0.065,0.1 mol)composite ceramics were successfully prepared by the solid-phase sintering method.The addition of ZnO further reduces the sintering temperature of composite ceramics to 930℃.The composite ceramic has a pure perovskite structure that can be found by XRD testing,which proves that CuO is successfully incorporated into the ceramic.Scanning and EDS energy spectrum proves that the ceramic structure is 0-3 composite structure.Through the dielectric temperature spectrum test,it is found that the ZnO composite further increases the phase transition temperature Tc of the composite ceramic on the basis of CuO.Through the research on the electrical properties of composite ceramics,z=0.05mol composite ceramics achieve the best comprehensive performance:Tr-t=114℃,Tc=192℃,d33=515 pC/N,d33*=859 pm/V,Pr=30.25 μC/cm2,Ec=8.1 kV/cm.ZnO composite also improves the temperature stability of ceramics to allow ceramics to be used in a wider temperature range.Based on these results,it can be seen that the combination of CuO doping and ZnO can further reduce the sintering temperature of ceramics while increasing the phase transition temperature and enhancing temperature stability.These results provide new ideas for the exploration of the subsequent low-temperature sintering process,and also broaden the application range of PSN-PMN-PT ternary ceramics. |
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